Chronic Illness in the United States. Volume IV Chronic Illness in the United States, Volume IV: Chronic Illness in a Large City — The Baltimore Study: The Baltimore Study [Reprint 2014 ed.] 9780674497665, 9780674497634


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Table of contents :
Preface
Introduction
Contents
PART I. Perspective
CHAPTER 1. STUDYING THE PROBLEM OF CHRONIC ILLNESS
CHAPTER 2. PLAN OF THE STUDY
PART II. The Volume and Character of Chronic Disease (Clinical Findings)
CHAPTER 3. PREVALENCE OF ALL CHRONIC DISEASES AND DISABILITY IN THE POPULATION
CHAPTER 4. PREVALENCE OF SELECTED DISEASES, THEIR CHARACTERISTICS AND DISABLING EFFECTS
CHAPTER 5. PREVALENCE OF DENTAL CONDITIONS
PART III. Needs for Care and Rehabilitation
CHAPTER 6. ESTIMATING NEEDS FOR CARE
CHAPTER 7. VOCATIONAL REHABILITATION
CHAPTER 8. SOCIAL AND ECONOMIC IMPLICATIONS
CHAPTER 9. ESTIMATED NEEDS FOR CARE OF A HIGH DISABILITY GROUP
CHAPTER 10. ESTIMATED NEEDS OF A REPRESENTATIVE SAMPLE FOR THREE ITEMS OF CARE
CHAPTER 11. ATTITUDES TOWARD HEALTH CONDITIONS
PART IV. Screening
CHAPTER 12. SCREENING FOR CHRONIC DISEASE
PART V. Disability Reported by the General Population
CHAPTER 13. DISABILITY REPORTED IN HOUSEHOLD INTERVIEWS
PART VI. Methods of Studying Chronic Disease in the General Population
CHAPTER 14. THE HOUSEHOLD INTERVIEW IN STUDIES OF PREVALENCE–AN EVALUATION
CHAPTER 15. ADDITIONAL SUGGESTIONS ON METHODOLOGY
APPENDICES
APPENDIX A. THE HOUSEHOLD SURVEY–METHODOLOGY
APPENDIX Β. THE CLINICAL EVALUATION–METHODOLOGY
APPENDIX C. THE CLINICAL EVALUATION–SUPPLEMENTARY INFORMATION ON STATISTICAL PROCEDURES
APPENDIX D. THE SCREENING CLINIC–METHODOLOGY AND SUPPLEMENTARY INFORMATION
APPENDIX E. HOUSEHOLD INTERVIEW SURVEY–ADDITIONAL STATISTICAL TABLES AND DEFINITIONS
APPENDIX F. CLINICAL EVALUATION–ADDITIONAL STATISTICAL TABLES
APPENDIX G. HOUSEHOLD INTERVIEW AND CLINICAL EVALUATION COMPARED–ADDITIONAL STATISTICAL TABLES
APPENDIX H. CLINICAL EVALUATION–FORMS AND WORK MATERIALS (INCLUDING DENTAL MATERIAL)
APPENDIX I. MULTIPLE SCREENING–FORMS AND WORK MATERIALS
APPENDIX J. MEMBERSHIP OF ADVISORY COMMITTEES
INDEX
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CHRONIC ILLNESS IN THE UNITED STATES

Chronic Illness in a Large City

COMMISSION ON CHRONIC ILLNESS June 1949-June 1956 AN INDEPENDENT NATIONAL AGENCY TO STUDY THE PROBLEMS OF CHRONIC DISEASE, ILLNESS, AND DISABILITY

FOUNDERS AMERICAN HOSPITAL

ASSOCIATION

A M E R I C A N M E D I C A L ASSOCIATION AMERICAN PUBLIC HEALTH AMERICAN PUBLIC WELFARE

ASSOCIATION ASSOCIATION

A STUDY OF THE PREVALENCE OF CHRONIC ILLNESS AND NEEDS FOR CARE IN AN URBAN AREA

Conducted

by

T H E C O M M I S S I O N ON CHRONIC

with assistance

ILLNESS

from

T H E JOHNS H O P K I N S UNIVERSITY AND HOSPITAL THE UNITED

STATES B U R E A U OF THE

Supported

by grants

from

T H E UNITED STATES PUBLIC HEALTH THE COMMONWEALTH

CENSUS

FUND

SERVICE

CHRONIC ILLNESS IN THE UNITED STATES VOLUME IV

Chronic Illness in a Large City The Baltimore Study

COMMISSION ON CHRONIC ILLNESS

Published for The Commonwealth

Fund

BY HARVARD UNIVERSITY PRESS Cambridge,

Massachusetts 1957

© 1957 BY THE COMMONWEALTH F U N D

Published for The Commonwealth Fund By Harvard University Press Cambridge, Massachusetts For approximately a quarter of a century

THE

COMMONWEALTH

FUND,

through its Division of Publications, sponsored, edited, produced, and distributed books and pamphlets germane to its purposes and operations as a philanthropic foundation. On July 1, 1951, the Fund entered into an arrangement by which HARVARD UNIVERSITY

PRESS

became

the publisher of Commonwealth Fund books, assuming responsibility for their production and distribution. The Fund continues to sponsor and edit its books, and cooperates with the Press in all phases of manufacture and distribution. Distributed in Great Britain By Oxford University Press London

LIBRARY OF CONGRESS CATALOG CARD N O .

56-10165

MANUFACTURED IN T H E UNITED STATES O F AMERICA

THE STUDY STAFF FOR THE STUDY AS A WHOLE DEAN W . ROBERTS, M.D., Director PETER G . MEEK, Assistant DEAN E . KRUEGER, Research

of the

Study

Director Associate*

MARVIN M . GLASSER, Research

Assistant

MRS. MARGERY R. CUNNINGHAM, Editorial Consultant

FOR SPECIAL ASPECTS T H E HOUSEHOLD INTERVIEW PHASE

U.S. Bureau of the Census Staff T H E CLINICAL EVALUATION PHASE

Supervised by Sarah Bowditch, M.D. Assisted by Mrs. Geneva Lundberg, Medical Social Work Consultant Edna Solomon, R.N., Public Health Nursing Consultant Ernest C. Allnutt, Jr., Vocational Rehabilitation

Consultant

T H E MULTIPLE SCREENING PHASE

Supervised by Charles M. Wylie, M.B., CH.B. Assisted by Frances Wickham, R.N., Nurse Administrator Donald J. Galagan, D.D.S.

* On detail from the Public Health Service.

COMMISSION ON CHRONIC ILLNESS OFFICERS

Chairman LEONARD W . MAYO ( 1 9 4 9 - 1 9 5 6 ) , New

York

Director, Association for the Aid of Crippled Children Vice-Chairman EDWIN S. HAMILTON, M.D. ( 1 9 5 0 - 1 9 5 6 ) , Kankakee,

III.

Member, Board of Trustees, American Medical Association Secretary J. D . COLMAN ( 1 9 4 9 - 1 9 5 6 ) ,

Baltimore

Vice-President, Johns Hopkins University and Hospital Treasurer THEODORE G . KLUMPP, M.D. ( 1 9 4 9 - 1 9 5 6 ) , New

York

President, Winthrop Laboratories, Inc. MEMBERS CREIGHTON BARKER, M.D. ( 1 9 4 9 - 1 9 5 6 ) , New

Haven

Executive Secretary, Connecticut Medical Society S. BRUCE BLACK ( 1 9 4 9 - 1 9 5 6 ) ,

Boston

President, Liberty Mutual Insurance Co. SARAH GIBSON BLANDINO ( 1 9 4 9 - 1 9 5 6 ) ,

Poughkeepsie

President, Vassar College »LESTER BRESLOW, M.D. ( 1 9 5 4 - 1 9 5 6 ) ,

Berkeley

Chief, Bureau of Chronic Diseases, California Department of Public Health DAVID BROCK, DJD.S. ( 1 9 5 2 - 1 9 5 6 ) , St.

Louis

Chairman, Council on Dental Health, American Dental Association MRS. W . DONALD BROWN ( 1 9 5 0 - 1 9 5 6 ) ,

Minneapolis

Attorney LEROY E . BURNEY, M.D. ( 1 9 5 3 - 1 9 5 6 ) ,

Washington

Assistant Surgeon General, Deputy Chief, Bureau of State Services, Public Health Service S. DEWRRRCLOUGH ( 1 9 4 9 - 1 9 5 5 ) ,

Chicago

Managing Director, Chicago Heart Association WARD DARLEY, M.D. ( 1 9 4 9 - 1 9 5 3 ) ,

Denver

President, University of Colorado JOSEPH W . FICHTER ( 1 9 4 9 - 1 9 5 6 ) , Oxford,

Ohio

Chairman, Ohio Farmers Union GEORGE A . HABERMAN ( 1 9 4 9 - 1 9 5 0 ) ,

Milwaukee

President, Wisconsin Federation of Labor E. L. HARMON, M.D. (1954-1956), Valhalla, N.Y. Director, Grasslands Hospital M A R K H . HARRINGTON ( 1 9 5 0 - 1 9 5 5 ) ,

Denver

Past President, National Tuberculosis Association CHARLES H . HOUSTON ( d e c e a s e d ) ( 1 9 4 9 - 1 9 5 0 ) ,

Washington

Attorney »RUTH HUBBARD, R.N. (deceased) (1953-1955), Philadelphia General Director, Visiting Nurse Society of Philadelphia * Served previously as technical adviser.

MRS. Κ . LIVINGSTON IRELAND ( 1 9 4 9 - 1 9 5 6 ) ,

Cleveland

Chairman, Committee on the Chronically 111, Welfare Federation of Cleveland ANDREW C . IVY, PH.D., M.D. ( 1 9 4 9 - 1 9 5 1 ) ,

Chicago

Vice-President, University of Illinois MRS. HUGH KIRKLAND ( 1 9 4 9 - 1 9 5 1 ) , Santa Barbara LEONARD W . LARSON, M.D. ( 1 9 5 1 - 1 9 5 4 ) , Bismarck,

N.D.

Member, Board of Trustees, American Medical Association SAMUEL L . LATIMER, JR. ( 1 9 4 9 - 1 9 5 6 ) , Columbia,

S.C.

Editor and Publisher of The State THOMAS A . MCGOLDRICK, M.D. ( d e c e a s e d ) ( 1 9 4 9 - 1 9 5 2 ) , KARL P . MEISTER ( 1 9 4 9 - 1 9 5 6 ) , Chicago

Brooklyn

Executive Secretary, Methodist Board of Hospitals and Homes JAMES R . MILLER, M.D. ( 1 9 4 9 - 1 9 5 6 ) ,

Hartford

Connecticut Commission for the Care and Treatment of the Chronically 111, Aged and Infirm * H E N R Y B . MULHOLLAND, M.D. ( 1 9 5 0 - 1 9 5 6 ) ,

Charlottesville

Professor, Department of Internal Medicine, University of Virginia School of Medicine MOST REV. WILLIAM T . MULLOY ( 1 9 4 9 - 1 9 5 4 ) , Covington,

Ky.

Bishop of Covington THOMAS P . MURDOCK, M.D. ( 1 9 5 1 - 1 9 5 6 ) , Meriden,

Conn.

Member, Board of Trustees, American Medical Association PETER H . ODEGARD ( 1 9 4 9 - 1 9 5 3 ) ,

Berkeley

Chairman, Department of Political Science, University of California THOMAS PARRAN, M.D. ( 1 9 4 9 - 1 9 5 6 ) ,

Pittsburgh

Dean, Graduate School of Public Health, University of Pittsburgh ELLEN C . POTTER, M.D. ( 1 9 4 9 - 1 9 5 6 ) ,

Trenton

Advisory Council on the Chronic Sick, New Jersey Department of Health *OLLIE A. RANDALL (1953-1956), New

York

Vice-Chairman, National Committee on the Aging WALTER P . REUTHER ( 1 9 4 9 - 1 9 5 5 ) ,

Detroit

President, Congress of Industrial Organizations DEAN W . ROBERTS, M.D. ( 1 9 4 9 - 1 9 5 6 ) ,

Baltimore

Director, Commission on Chronic Illness EDWARD S. ROGERS, M.D. ( 1 9 4 9 - 1 9 5 6 ) ,

Berkeley

Professor of Public Health and Medical Administration, University of California School of Public Health MEFFORD R . RUNYON ( 1 9 5 3 - 1 9 5 6 ) , New

York

Executive Vice-President, American Cancer Society MRS. RAYMOND SAYRE ( 1 9 4 9 - 1 9 5 2 ) , Ackworth,

Iowa

President, The Associated Women of the American Farm Bureau Federation SIDNEY L. SCHWARZ (1949-1953), Chicago

Industrialist MRS. LUCILLE M . SMITH ( 1 9 4 9 - 1 9 5 6 ) ,

Washington

Chief, Health Services Organization Branch, Division of Public Health Methods, Public Health Service ALBERT W . SNOKE, M.D. ( 1 9 4 9 - 1 9 5 4 ) , New

Haven

Director, Grace-New Haven Community Hospital ERNEST L . STEBBINS, M.D. ( 1 9 5 2 - 1 9 5 6 ) ,

Baltimore

Director, Johns Hopkins School of Hygiene and Public Health RT. REV. CHARLES A . TOWELL ( 1 9 5 4 - 1 9 5 6 ) , Ludlow,

Ky.

Diocesan Director of Hospitals WILLIAM C . TREUHAFT ( 1 9 5 4 - 1 9 5 6 ) ,

Cleveland

President, Tremco Manufacturing Co. THOMAS J . S. WAXTER ( 1 9 4 9 - 1 9 5 6 ) ,

Baltimore

Director, Maryland State Department of Public Welfare * Served previously as technical adviser.

Preface book is the report of the Commission on Chronic Illness on its study of prevalence of chronic illness and needs for care in an urban community. Its purpose is to present the results of that study. It is the fourth and final volume of the Commission's series of reports, which includes also Volume I, Prevention of Chronic Illness; Volume II, Care of the LongTerm Patient; and Volume III, Chronic Illness in a Rural Area. The current report is a companion to Volume III and complements the picture there presented of chronic illness in a rural community. It is a staff document, prepared under the Commission's sponsorship and direction. In common with the rural study, it bears a different relationship to the Commission than do the first two books in the series inasmuch as those—the reports on prevention and on care—are built around recommendations framed and promulgated by the Commission. The study here reported was financed principally by the United States Public Health Service through a series of research grants, and by the Commonwealth Fund, with some assistance also from the Eli Lilly Company. It was greatly facilitated by the United States Bureau of the Census, which carried major responsibility for the design and conduct of the household interview phase. Also invaluable was the aid of The Johns Hopkins Hospital, particularly its Medicine I Clinic, in making its medical personnel and facilities available for the clinical evaluation work. THIS

LEONARD W . Chairman, December

1956

MAYO

Commission

on Chronic

Illness

Introduction The Commission on Chronic Illness The Commission on Chronic Illness was an independent, voluntary organization created by the American Hospital Association, the American Medical Association, the American Public Health Association, and the American Public Welfare Association. The purpose of its seven-year program has been to review and assess the chronic illness problem and attempt to bring order, cohesion, and direction to the many related but unintegrated efforts to prevent and control chronic disease and minimize its disabling effects. The Impetus for This Study One of the Commission's stated goals was to "define the problems arising from chronic disease in all age groups." The realization of this goal, it was obvious, required basic facts about the chronically ill—who they are, how many there are, their ages, the kinds and extent of their disabilities, their characteristics, the care they need. A review of the past and current scene indicated that the needed information had not been or was not being gathered by any other group sufficiently recently, with sufficient precision, or in sufficient breadth. Subsequently, several other organizations did undertake projects which were expected to provide at least some of this knowledge. These projects were the studies of health and sickness experiences of families insured under the Health Insurance Plan of Greater New York; the studies of community health conducted in Pittsburgh under the auspices of the Schools of Medicine and Public Health of the University of Pittsburgh and the Pittsburgh Department of Public Health; the Rehabilitation Survey and Demonstration conducted by Community Studies in Kansas City; and the state-wide study of methods for obtaining current measures of illness made by the California Department of Public Health. However, at the time of their conception, the study here reported and the companion survey in a rural area were unique in that they were the only projects which held promise of producing the necessary basic knowledge. In order to advance its goal of defining the problems arising from xii

INTRODUCTION

xiü

chronic disease, the Commission found it imperative to sponsor these two studies. Form of This Study

and lis

Coverage

Ideally, a study of the prevalence of chronic illness and needs for care should be nation-wide. However, tremendous organizational, administrative, and financial problems characterize such a study on a nation-wide basis. The limited time and funds available to the Commission precluded making the contemplated study on a national scale, but did permit its conduct in selected communities. The Commission therefore decided to conduct the study in two localities, one rural and one urban, in the expectation of producing data and methods of study which could be useful also in other areas. The communities chosen were Baltimore, Maryland, and Hunterdon County, New Jersey. In considering the patients to be surveyed, the Commission was aware that "chronic illness" and "chronic disease" are terms about which there is no general agreement on exact meaning and for which there are no commonly accepted definitions. The Commission has utilized a number of different definitions of chronic disease and illness at different times. Each of these was adopted and adapted to the purpose to be accomplished and usually served that purpose well. As applied to disease or illness, the word "chronic" means "long continued" or "of long duration." It is the opposite of "acute," a term usually applied to diseases such as typhoid fever, pneumonia, the common cold, and appendicitis which, in the absence of complications, typically run a short, self-limited course. Efforts have been made to classify all diseases as either acute or chronic on the basis of their usual duration. Convenient as this would be, no one has been able to develop a satisfactory classification on this basis. If one were to list all diseases in order of their usual duration, there would be little difficulty in identifying those diseases at one end of the list as acute and diseases at the other end as chronic. However, much of the list would consist of diseases that are sometimes acute and sometimes chronic. A cerebral hemorrhage may be sudden and almost immediately fatal—an acute illness. On the other hand, cerebral hemorrhage usually does not kill immediately but produces varying degrees of disability which may persist for months or years. Whether a disease will be acute or chronic may depend on the timing of treatment. Early cancer of certain types may be completely cured by surgery, but if untreated may lead to a long-lasting disability. Many infections such as sinusitis, cholecystitis, colitis, and cystitis may occur as

INTRODUCTION

xiv

acute, brief illnesses, or they may exist as chronic, long-lasting infections. The problem of definition for purposes of this study was complicated also by another factor: the project was interested in disability of any kind, no matter what its cause. The study was not limited to disabling conditions resulting from disease processes, but extended also to disability resulting from other causes such as trauma or congenital malformations. At the outset the objective was to get a description of all illness and disability problems reported to exist by the population of the area being studied. As the study developed, certain criteria (which are described later) were employed to select individuals for further participation in the study. These criteria might be considered components of a definition of chronic illness, as might other criteria employed in the selection of data for presentation in this report that would focus attention on health conditions and disabilities which the study staff wished to emphasize in discussing "chronic illness." Plan of Organization

of This

Report

Part I, "Perspective," contains a brief review of preceding efforts to study the size and scope of the chronic illness problem. The section presents the objectives of the Commission's studies in Baltimore and in Hunterdon County, New Jersey, and describes the study plan and general methodology of the Baltimore survey. Parts II and III, respectively, are concerned with "The Volume and Character of Chronic Disease" and "Needs for Care and Rehabilitation." Part IV is devoted to the results of screening tests carried out in the evaluation clinic and to discussion of the physiologic characteristics of the population as observed there and in the multiple screening clinic which was operated as one step in the study. Part V contains information on disability in the general population as reported in household interviews about health. Part VI is of concern primarily to individuals interested in planning future morbidity studies based on interviews with members of selected households about the state of their health and the health of others living with them. This section of the report compares the information on prevalence of chronic disease reported at the household interviews with the more precise and complete information revealed by searching histories and physical examinations done by physicians and supplemented in some cases by a medical social worker, a public health nurse, and a vocational counsellor. The appendices contain a detailed description of the study methodology, the statistical tables on which the report is based, and copies of the work materials.

INTRODUCTION

XV

Highlights of This Report A representative sample of an entire noninstitutional urban population group was studied exhaustively to see what existed in it in the way of chronic disease and disability resulting from chronic conditions; to discover the variations in prevalence of chronic disease and disability by age, sex, color, economic level, and other significant social and economic factors; to determine the needs of the chronically ill for care, and the rehabilitative potential of chronically ill and disabled individuals; and, in the process, to test new methods for studying the nature and magnitude of the chronic disease problem. Using the extensive resources of a university medical center, the sample was examined to determine the amount and kind of chronic disease existing in the general population. The study found wide deviations from levels and patterns of prevalence suggested by earlier studies which used less exhaustive methods. Nearly 1,600 chronic conditions per 1,000 population were diagnosed in this examination. Prevalence rates were developed for each chronic disease. For example, the prevalence of heart disease of all types was found to be 96 per 1,000 population. The rate for hypertension without heart involvement was 66 per 1,000. Such rates are far above those previously available predicated on other studies. While it is true that no other study is strictly comparable, nevertheless the divergence in rates is so great as to be impressive. It is even more striking in view of the fact that an important group of the chronically ill—persons in long-term medical care institutions and thus presumably the most severely affected by chronic illness—were not included in the Baltimore survey. In addition to surprisingly high rates for some diseases, the relative importance of diseases in terms of prevalence was found to differ from the generally accepted order of rank. Arthritis is usually considered to be the most widely prevalent of the chronic diseases, butin the Baltimore population its rate of prevalence (75 per 1,000 persons) was exceeded by the heart disease rate and the rate for mental disorders (109 per 1,000). Of special interest in view of the high prevalence rates is the fact that only one eighth of the conditions were judged to be in a severe stage; and another 25 per cent were moderate in severity. More than half of the conditions (56 per cent) were judged to be "substantial" 1 —but less than 1 That is, they interfered with or limited the patient's activities or required care or were likely to do either of these in the future. Most often it was the requirement of care rather than interference with or limitation on activities that caused a condition to be classified as substantial.

xvi

INTRODUCTION

half of the people (44 per cent) had a substantial condition. The prognoses for the substantial conditions indicated that if no care was given more than 4 out of 10 conditions would be slowly progressive, more than one fourth would remain stationary, and very few would be expected to improve. With recommended care, however, only 1 out of 7 conditions would continue to progress; another one seventh would remain stationary; while improvement (including complete recovery for one tenth) should occur for 4 out of 10 cases. Two approaches were used in measuring the extent of disability. Despite the fact that slightly more than half the conditions were substantial, both approaches showed the amount of disability to be small. It must be remembered, however, that the sample excluded the disabled who were being cared for in long-term medical institutions. The first approach depended upon the patient's idea of the disabling effect of his condition as reported in a household interview. According to the interview reports, 3 per cent of the population were disabled (i.e., kept from their usual activities) by acute or chronic disease on the day before the interview, and on the average there was about one day of disability per person during the immediately preceding four-week period. Persons in the lowest income group reported they had two to three times more days of disability due to chronic conditions than did persons in the higher income groups; and the data suggest that disabling illness is more importantly a cause than an effect of low income. Secondly, the examining physicians in the evaluation clinic recorded their judgments as to the disabling effect of chronic conditions. According to these data, 4 per cent of the population had some limitation with respect to the activities of normal daily living, and 6 per cent were limited in their ability to carry out their usual activities of working, keeping house, or attending school. Among people with either of these kinds of limitations, the potential for decreasing the limitation was small. Among those for whom improvement with respect to ability to work was considered medically feasible, success of rehabilitation was judged probable for only half. The most frequently mentioned major obstacle to success of rehabilitation was the attitude of the patient toward removal or by-passing of his disability. The administration of multiple screening tests to persons examined in the evaluation clinic created the opportunity to compare the test results for the group with the findings of a thorough diagnostic study. In the comparison a relatively high percentage of the positive tests were confirmed as due to disease. The high rate of confirmations undoubtedly

INTRODUCTION

xvii

is in large measure a reflection of the thoroughness of the diagnostic evaluation. This finding has important implications for screening in that it suggests that the low rate of confirmations reported in many screening studies may be a measure of the inadequacy of the diagnostic follow-up rather than inadequacy of the screening tests. The Baltimore survey included a dental examination because of the rare opportunity it presented to obtain data on the dental status of a representative population group. Not unexpectedly, the findings showed a high prevalence of dental disease and a great backlog of unmet dental needs—despite the fact that in the household interviews only 3 per cent of the people reported dental problems. A case-by-case comparison of household interview reports with clinical evaluation diagnoses was not a formally stated objective of the study. Nevertheless, when this comparison was made it produced some arresting information which has far-reaching implications for planners of subsequent morbidity studies of a sample of the general population. It showed that less than one fourth of all conditions diagnosed in the clinical examination were reported in the preceding household interview in terms generally related to the subsequent diagnosis. Omitting from the comparison the conditions which could not have been reported (because they were not obvious to the patient or his family and had never caused symptoms or been diagnosed by a physician) raised the ratio to only 3 out of 10 evaluation diagnoses matched by interview reports. Nor was the reporting substantially better for more severe cases of disease. Attitudes toward health conditions was a second subject area not specifically included in the study plan. Upon examination, however, people's attitudes toward health and medical care were found to be major obstacles to the application of available therapeutic measures. Of a selected high disability sample, more than half of the patients were judged to need to adjust their attitudes toward their disease, and more than one third their attitudes toward recommended care of the disease. "Unfortunate" attitudes toward health were reflected also in people's reluctance to accept the diagnostic study offered them in the clinical evaluation. Because of the implications for health education, an attempt has been made in this report to analyze the attitudes displayed by the persons under study in the clinical evaluation. Acknowledgments

The staff of the Commission did not' possess all the skills and resources necessary for the successful prosecution of this rather complex study. We

xviii

INTRODUCTION

were fortunate that other agencies having these skills were interested in the project and were willing to assist with certain phases of the work on the basis of specific contractual agreements, and that many individuals gave freely of their time and skill in their areas of special competence. We are greatly indebted to the Bureau of the Census, which carried major responsibility for the household interview phase of the study. The Bureau designed and field tested the interview schedule, selected the sample, conducted the interviews, and tabulated the findings according to specifications of the Commission. The clinical evaluation phase of the study could not have been carried out without the participation of a medical center with extensive clinical facilities. It was our good fortune that the Medicine I Clinic of The Johns Hopkins Hospital was interested in this phase of the study and made its resources available to the Commission. We particularly wish to thank Dr. J. E. Moore, Physician-in-Charge of the Medicine I Clinic, and his associates, Dr. Richard Hahn, Dr. John Hume, and Dr. Ernest Smith, who, together with their colleagues, carried out the clinical evaluation of the patients in the study. William G. Cochran, Professor of Biostatistics, The Johns Hopkins University School of Hygiene and Public Health, gave valuable counsel on several aspects of the study, particularly on sampling methods and consideration of possible sources of bias in the data. Various units of the Public Health Service participated in many ways. The Division of Dental Public Health assisted in the design of the dental phase of the study and provided most of the dentists who performed examinations in the multiple screening step. The National Heart Institute of the National Institutes of Health assigned a statistician to the Commission throughout the study. The Chronic Disease Branch gave advice and assistance many times and lent technical equipment which was needed. The Division of Public Health Methods assisted with technical and statistical problems on many occasions and cooperated with the Bureau of the Census in diagnostic coding. We are indebted to the Maryland State Department of Health for the use of Bennett Hall for the multiple screening step, and to the Anne Arundel County Health Department for the loan of a supervising nurse for this phase of the study. The Division of Vocational Rehabilitation of the Maryland State Department of Education supported the study through the loan of a senior vocational rehabilitation counsellor for approximately a year to assist in evaluation of rehabilitation potential. This bare accounting fails by a wide margin to reflect the real contribu-

INTRODUCTION

xix

tion made by these groups and individuals. It fails also to recognize the extent to which the work was furthered by still other persons who by their counsel or by their extraordinary application to seemingly small jobs, earned an important share of the credit. To all who worked on the study the Commission wishes to express again its thanks and its realization that only such a cooperative effort as they put forth could have made the project possible. DEAN W. ROBERTS, M.D. Director, Commission on Chronic Illness December 1956

Contents Preface

xi

Introduction

xii

Part I

Perspective

CHAPTER 1 2

Part II

The Volume and Character of Chronic 3

25

Plan of the Study

(Clinical CHAPTER

Disease

Findings)

Prevalence of All Chronic Diseases and 47

Disability in the Population CHAPTER

4

Prevalence of Selected Diseases,

Their

Charac73

teristics and Disabling Effects CHAPTER

5

3

Studying the Problem of Chronic Illness

CHAPTER

Prevalence of Dental

105

Conditions

Part III

Needs for Care and

CHAPTER

6

Estimating Needs for Care

Rehabilitation 121

CHAPTER

7

Vocational

131

CHAPTER

8

Social and Economic

CHAPTER

9

Estimated Needs for Care of a High Disability Group

CHAPTER

10 Estimated Needs of a Representative

CHAPTER

11 Attitudes

Rehabilitation

151

Implications

171 Sample 193

for Three Items of Care

Part IV

toward Health Conditions

Screening

CHAPTER 12 Screening for Chronic Disease Part V

Disability Reported

by the General

219 Population

CHAPTER

13 Disability Reported in Household

Part VI

Methods of Studying Chronic Disease in the General

Interviews

265

Population

CHAPTER 14 The Household Prevalence—An CHAPTER

201

15 Additional

Interview in Studies of Evaluation

Suggestions on Methodology

295 329

xxii

CONTENTS

Appendices A

APPENDIX

Β

The Clinical

APPENDIX

C

The Clinical

APPENDIX

D

APPENDIX

E

Information

F

341

Evaluation—Methodology

371

Evaluation—Supplementary Clinic—Methodology

Supplementary

Information

Household Clinical

409

on Statistical Procedures

The Screening

Statistical APPENDIX

Survey—Methodology

The Household

APPENDIX

Interview

and 437

Survey—Additional 491

Tables and Definitions Evaluation—Additional

Statistical 511

Tables APPENDIX

G

Household

Interview and Clinical

Compared—Additional APPENDIX

H

Clinical

Evaluation—Forms

(Including APPENDIX APPENDIX

Index

Statistical

I

Multiple

J

Membership

Dental

Evaluation 555

Tables

and Work

Materials 571

Material)

Screening—Forms of Advisory

and Work Materials Committees

585 589 597

PART I

Perspective

CHAPTER 1 STUDYING THE PROBLEM OF CHRONIC ILLNESS

The Need for New Knowledge Basic and Applied Medical Research Public Health Research Mortality Statistics Morbidity Statistics Techniques of Studying Morbidity in the General Population Usefulness and Limitations of Existing Morbidity Data The Commission's Decision to Conduct a Survey

5 6 7 8 8 14 18 20

Chapter

1 Studying the Problem of Chronic Illness THE NEED FOR NEW KNOWLEDGE

The Commission on Chronic Illness reviewed the past and current scene before deciding that the information it desired was not being obtained through the studies of others and that, in order to accomplish its assignment, the Commission would need to undertake research aimed at defining the size and nature of the chronic illness problem. At the first meeting of the Commission in May 1949, a group of technical advisers had recommended that the Commission should "first, comb t h r o u g h . . . (an entire definite population group) . . . to see what exactly exists in it in the way of chronic disease; secondly, to determine what is being done about those persons who have chronic disease—how many of them are in their own homes; how many in institutions, hospitals, nursing homes; how many are receiving rehabilitation service and other kinds of services that they ought to receive; and finally, to set forth by some arbitrary judgments on the part of technicians, what kinds of services and facilities ought to be available to meet the problems in the particular group studied." 1 This, then, was the information about chronic illness that the Commission decided had not been obtained by the studies of others and was not in process of being obtained in 1950. It is, and was at that time, generally recognized that control of many chronic diseases must await new knowledge about their cause and cure. Although many advances are being made, large gaps remain in our present understanding of, for example, the processes underlying arteriosclerosis and neoplastic growth. The narrowing of gaps of this kind depends on further general physiologic research and on research directed toward the causes and cures of particular diseases—that is, on basic and applied medical research. Another type of gap in our knowledge exists also. This is the gap which 1 Commission on Chronic Illness. Proceedings p. 38.

5

of First Meeting,

May 20, 1949,

6

PERSPECTIVE

represents what we do not know about the impact of chronic disease on the individual, his family, and the community; about the socioeconomic circumstances which are related to disease as antecedents, concomitants, or results; about how many of what kind of people have or can be expected to have what diseases; and about the kinds and amount of medical and social services required to prevent or treat these diseases. This kind of information is only an incidental (and frequently missing) result of basic and applied medical research; it is best obtained through public health research. BASIC AND APPLIED MEDICAL RESEARCH

The difficulty is not that chronic disease has been ignored by those engaged in medical research. Many countries have fostered medical and other scientific research through the years. The various chronic diseases have been the subject of this scientific curiosity as have been the acute diseases. Most people are aware of the great advances in health knowledge. They are familiar with the fact that since the beginning of this century human life has been greatly prolonged through the application of scientific knowledge. Prevention and control of diseases with a high mortality in the first few years of life have vastly improved; so has prevention or amelioration of infectious or communicable diseases. Two major chronic diseases, diabetes and syphilis, have become far less threatening to human happiness through the discovery of methods of early diagnosis and effective therapy—the culmination of years of research effort. In recent years our annual national investment in clinical and laboratory research relating to medicine has been substantial. For example, in 1950, the year the Commission reached its decision to undertake research, more than $33 million in awards—most of it for clinical and laboratory work—was registered with the Medical Sciences Information Exchange of the National Research Council. Öf this total, about $21 million came from government sources in the form of 2,052 separate grants and more than $11 million from private groups and organizations through 1,265 grants.2 Not included in these figures are some additional government expenditures made for medical research that year and most of the awards made by industry, local foundations, or funds established solely for individual universities. In 1950, 15 of the national voluntary 2 Deignan, Stella Leche, and Miller, Esther. "The Support of Research in Medical and Allied Fields for the Period 1946 through 1951." Science 115:322, March 28, 1952, Table 1.

THE PROBLEM OF CHRONIC ILLNESS

7

agencies, almost all of them concerned with chronic disease, allocated over $9 million for medical research. 3 (A substantial portion of this amount was registered with the National Research Council and is included in the total mentioned above.) By 1950, 140 life insurance companies had contributed over $3 million to their own fund, the Life Insurance Medical Research Fund, set up in 1945 for research in heart disease alone.4 Since 1950, medical research expenditures by both government and private sources have increased and have continued to be devoted primarily to basic and applied medical research. It is little wonder, then, that one of the groups of experts meeting at the Commission's invitation to consider research needs in the field concluded that clinical research and laboratory research in the biologic and physical sciences relating to medicine were being "strongly supported." 5 PUBLIC HEALTH

RESEARCH

The range of public health research in communities is both broad and deep. A special committee appointed by the National Advisory Health Council [advisory to the Surgeon General, Public Health Service] has classified this research in five main groups: 1. Studies related to the extent and distribution of diseases or other public health problems in a community, a population, or part of a population. 2. Studies, on a community, population, or group basis, in relation to the pathogenesis or dissemination of diseases of public health importance. 3. Studies of the effectiveness of prophylactic or therapeutic procedures on a community, population, or group basis. 4. Studies designed to test the significance of a laboratory or clinical finding, or to test the validity of a laboratory technique, on a community, population, or group basis in relation to problems of public health importance. 5. Studies of public health methods.® One of the phases of public health research, and specifically type 1 of the above listing, includes the study of the effect of chronic illness and disability on people, the magnitude of the problem, and its ramifications. ""General Funds Raised and Medical Research Funds. Allocated by Voluntary Health Agencies Interested in Specific Diseases." The New York Times, September 1953. * Life Insurance Medical Research Fund. Seventh Annual Report, 1951-52, p. 17. 5 Study Group Reports, Committee IV—Research, National Conference on Care of the Long-Term Patient, p. 2. " Ciocco, Antonio, and Ring, Martha D. "Pittsburgh Meeting of Public Health Study Section—An Evaluation of Study Methods." Public Health Reports 66:892, July 13, 1951.

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PERSPECTIVE

This has not been as vigorously and extensively pursued as has basic and applied medical research. Such study involves identifying and counting health conditions in people. The two common sources for such counts are studies of mortality and morbidity. MORTALITY STATISTICS

Death statistics are available for the total population except as they suffer from a minor degree of underreporting and a somewhat larger degree of inaccuracy. They cover both acute and chronic disease and are so recorded that the chronic disease statistics can be segregated for analysis. But death statistics, though valuable sources of information on mortality by cause, for various age, sex, and racial groups and for various parts of the country, give no clue to prevalence of nonfatal disease at any particular time or to the age at which the disease was first manifest. They give no information on the duration of illness or the income levels and living conditions of those who died. Neither do they take into consideration illnesses other than the immediate and underlying causes of death. Their shortcomings in these regards are one of the reasons why it can be said that "our present knowledge of nonfatal illness in the United States is no further advanced than the knowledge of fatal illness at the beginning of the century." 7 The limitations of mortality data are of great significance to the chronic illness picture. Many of the chronic diseases or handicaps—such as arthritis, mental disorders, blindness, deafness, and hernia—are seldom the immediate or the underlying cause of death. At the same time they are the cause of much disability, of economic loss to the family and community, and of drain upon community resources for health and welfare, and thus are of great social and economic importance. Clearly, mortality records alone fall short of providing the needed information on problems of chronic illness. MORBIDITY STATISTICS

Disease

Reporting

by

Physicians

There are several sources of morbidity8 data. The first is morbidity reporting by physicians to official health departments. Included among the "reportable" diseases which these data cover are some acute and some 7 Dorn, Harold F., M.D. "Some Problems for Research in Mortality and Morbidity." Public Health Reports 71:5, January 1956. 8 The term morbidity is used in a general sense to include all conditions, regardless of whether they cause illness.

THE PROBLEM OF CHRONIC ILLNESS

9

chronic communicable diseases—although most major chronic diseases are not reportable. Theoretically, all reportable diseases in the entire population are thus recorded. In practice, reporting has been nearly complete for some diseases in some geographic areas, but in general less than half of the communicable disease cases in the United States are reported. 9 The specifications with regard to reporting by physicians and the limitations of the system are such that very little data on chronic disease are derived from this source. Some communities have established disease registries for particular conditions as an adjunct to service programs. Much of the information for these registries has been obtained through morbidity reporting by physicians and hospitals and supplemented by information from other sources. Tuberculosis case registries have been valuable in control programs and the data in these registries have been useful in studying the distribution of known cases of tuberculosis in the population. Case registries have also been useful in studying cancer, rheumatic fever, and other crippling conditions. A particular value of these registries is the opportunity they provide for longitudinal studies. A weakness is the incompleteness of their data owing to underreporting and the omission of cases not known to physicians and hospitals. Disease Reporting by the General

Population

A second source of morbidity data is reporting by the people themselves. It has seemed reasonable that an effective way to get information about people's diseases is to ask people about them. This method, usually employing a personal interview by a lay person with an individual or a family, has been used often during the past few decades. It can be adapted to solicit information of various kinds, depending upon the goals and the emphases of a particular study. Most of the studies which have so far applied the method have secured data about both acute and chronic disease. None of the studies up to now have been carried on as part of the administrative operation of a health program; rather, they have been special projects. Thus the cost of conducting them has been substantial, and the high cost is in turn partly responsible for the fact that they have been limited in number and scope. Some have been carried out on a sample of the population of the nation, but the majority have been conducted • Cobb, Sidney, M.D. "Some Problems in Obtaining Data on Prevalence of Illness." Study Group Reports, Committee IV—Research, National Conference on Care of the Long-Term Patient, p. 60.

10

PERSPECTIVE

within narrow geographic boundaries and have used only a sample, rather than all, of the population of those areas. Morbidity survey in Hagerstown, Maryland. The first scientific statistical investigation of the state of health of a group of the general population by means of personal interview took place in Hagerstown, Maryland, in 1921-1924. In cooperation with the Hagerstown Health Department, representatives of the United States Public Health Service surveyed 1,822 white families (a third of the population) at intervals of 6 to 8 weeks for 29 months. Each person in these families was interviewed—parents answering for their children—and was asked what ailments, acute or chronic, he or she had had since the time of the last interview, the duration of those ailments, their course, etc. Cases of both nondisabling and disabling illness were included.10 A resurvey concentrating on chronic disease was conducted 20 years later among 1,943 of the approximately 5,000 individuals who had been reported to be free of chronic disease in the 1921-1924 interviews. In cases where death had occurred during the 20-year intervening period the cause of death was determined, and those deaths resulting from a chronic disease were included in the 20-year figures on incidence of chronic disease. These were converted into four 5-year rates of incidence.11 Perhaps the best way to indicate the coverage of a particular survey through periodic interviews about health is in terms of the number of persons surveyed multiplied by the number of years each person was included in the survey. In these terms the Hagerstown study secured illness data on 16,500 "person-years." Other periodic morbidity surveys by the Public Health Service. Between 1928 and 1931, jointly with the Committee on the Costs of Medical Care, the Public Health Service obtained information on the incidence of episodes of sickness reported by 9,000 families in 130 localities, mostly urban areas, of all sizes located in 18 states. During a 12-month period a series of visits was made to the home of each family to obtain, by an interview with the housewife or other responsible member of the house10 Sydenstricker, Edgar. Hagerstown Morbidity Studies—A Study of Illness in a Typical Population Group (a collection of 12 reprints from Public Health Reports). Washington, D.C., Government Printing Office, 1930. "Lawrence, P. S. "An Estimate of the Incidence of Chronic Disease." Public Health Reports 63:69-82, January 16, 1948.

THE PROBLEM OF CHRONIC ILLNESS

11

hold, information about illness and medical and dental care received. Information recorded about each illness, acute or chronic, included the diagnosis or cause of the illness, date of onset, duration of the illness, and many facts about the nature and extent of medical care provided by various kinds of practitioners and institutions. Costs were also obtained.12 The survey included 43,000 person-years of observation. The Public Health Service cooperated with the Milbank Memorial Fund to make a similar survey in 1929-1932 of a sample of the population of Cattaraugus County, New York (10,000 person-years of observation), and, in 1930-1931 of a sample of the residents of Syracuse, New York (6,000 person-years of observation) ,13 Over the 5-year period from 1938-1943, the Public Health Service joined with the Milbank Memorial Fund, the Departments of Biostatistics and Epidemiology of The Johns Hopkins University School of Hygiene and Public Health, and the Baltimore City Health Department in a survey of families living in 35 city blocks in the Eastern Health District of Baltimore,14 including 21,500 person-years of observation. These three surveys of a sample of the population of a locality— Cattaraugus County, Syracuse, and the Eastern Health District—are similar in that each involved periodic interviews with an adult member of each household about cases of illness during the interval since the previous interview, each covered both acute and chronic disease, and each secured information about both nondisabling and disabling cases and about the severity of disability. Data from these three surveys, the survey conducted in Hagerstown, Maryland, and the survey of 130 localities in 18 states had enough elements in common to warrant combination of some of the data to provide a larger volume of sickness experience and more reliable sickness rates in relation to age, sex, and other factors than any one of the surveys yielded.15 Together, they comprise more than 80,000, and for some kinds of data nearly 100,000, person-years of observation. 12 Collins, Selwyn D. The Incidence of Illness and the Volume of Medical Services among 9,000 Canvassed Families (a collection of 23 reprints). Washington, D.C., Government Printing Office, 1944. M Collins, Selwyn D., Trantham, Katharine S., and Lehmann, Josephine L. Sickness Experience in Selected Areas of the United States. Public Health Monograph No. 25, PHS Publication No. 390. Washington, D.C., Government Printing Office, 1955. 11 Collins, Selwyn D., Phillips, F. Ruth, and Oliver, Dorothy S. "Specific Causes of Illness Found in Monthly Canvasses of Families : Sample of the Eastern Health District of Baltimore, 1938-43." Public Health Reports 65:1235-1264, September 29, 1950. 15 Collins, Trantham, and Lehmann. Op. cit.

12

PERSPECTIVE 16

The National Health Survey. Data from the old National Health Survey, a project conducted by the Public Health Service with financial aid from the Works Progress Administration, constitute the largest assembly of morbidity information thus far gathered in the United States. The survey was made in 1935-1936. The population surveyed was interviewed only once, as contrasted with the periodic reinterviews in the morbidity studies described above. In the course of this National Health Survey 800,000 families, including 2,800,000 persons in 83 cities and 23 rural areas in 19 states, were visited. These families were so distributed as to give a sample which was, in general, representative of the United States according to size and region, except that the coverage of cities was much more complete than the coverage of rural areas. One member of each household was interviewed about basic social data on all members, about illnesses and disabilities which kept a member from his usual activity on the day of the survey or for 7 days or more during the preceding 12 months, about chronic diseases or impairments whether or not disabling, and about certain facts with regard to the kinds and amount of medical care received. In this survey the long period of time about which illness data were requested in a single interview and the minimum duration of 7 days for inclusion of nonchronic diseases placed more emphasis on chronic disease than on short-term conditions. The National Health Survey has been the source used most frequently in deriving estimates of the rates of prevalence of chronic disease in the United States. By 1951 the Surgeon General estimated that National Health Survey findings had formed the basis for 200 reports, articles, and comparative studies. The data have been used to project estimates based on the changed age distribution of the population for more recent years and to estimate the number of cases of chronic disease in individual communities for purposes of measuring needs for hospital and other facilities and for community services. The 1949 and 1950 Current Population Survey of disabling illness.17 In 1950 the most recent data upon which national estimates of the prev16 Illness and Medical Care among 2,500,000 Persons in 83 Cities, with Special Reference to Socio-Economic Factors (a collection of 27 reprints). Washington, D.C., Government Printing Office, 1945. 17 Woolsey, Theodore D . Estimates of Disabling Illness Prevalence in the United States. Public Health Monograph No. 4, PHS Publication No. 181. Washington, O.C., Government Printing Office, 1953.

THE PROBLEM OF CHRONIC ILLNESS

13

alence of disabling illness could be based were the results of several questions that had been included in the February 1949 and September 1950 Current Population Survey of the Bureau of the Census.18 The questions were answered by an adult member of the family for all members. They solicited information as to how many disabling illnesses existed among persons from 14 to 64 years of age on the day before the interview, and on the continuous duration of those disabilities. Disability was defined as inability to carry on usual work or other duties because of illness or disability. People whose disabilities allowed them to work only occasionally were counted as disabled along with those unable to work at all. The cause of disability, i.e., diagnosis, was not secured in this survey, nor was any measure of severity other than duration. Morbidity studies in other countries. Information about illness among the people of other countries was of interest to the Commission, though it was not a satisfactory substitute for data on the people of the United States. In 1950 only one other country, Great Britain, had made a national morbidity survey. Conducted by the Ministry of Health, it was a periodic survey of the health of a sample of the population, with a different sample of households being covered by successive phases of the survey. It began in 1943 and continued to 1952 when, according to one report, 19 exigencies of national finances forced its discontinuance. Canada and Denmark were beginning field work on national morbidity surveys by means of household interviews in 1950 (the results to be made available several years later). Data on Chronic Disease in Selected Groups Substantial amounts of data on illness are available for selected groups of the population which are unrepresentative, to varying degrees, of the general population. One source of such data is the statistics gathered by agencies engaged in providing medical or hospital care. Thus, data may be available on illness among, for example, the recipients of public assistance, selective service registrants, the employees of a company, the members of a union, the participants in a prepayment plan, the policy-holders of an insurance company. 18 The Current Population Survey of a nation-wide sample of 25,000 households is made monthly to measure changes in the labor force and various characteristics of the population. 19 "The Danish National Morbidity Survey of 1950." Communication No. 7 from the Committee on the Morbidity Survey. Danish Medical Bulletin 2:148-152, 1955.

14

PERSPECTIVE

Another body of data on chronic illness among selected groups of the population comes from studies in localities or larger areas of particular aspects of the chronic illness problem. Thus, a community may be concerned about the adequacy of care of patients in nursing homes and study the characteristics of the patients and the amount and kinds of care they receive. The first study of this kind was made by Jarrett for the Welfare Council of New York City in 1928.20 It was directed toward the broad implications of chronic illness for a small segment of the population—persons dependent on welfare agencies for subsistence or medical care, or both. A similar limitation characterized the state-wide surveys conducted by Bigelow and Lombard for the Massachusetts Health Department from 1929 to 1931. 21 Subsequently, 4 other states—Connecticut in 1944, New York and Illinois in 1947, and California in 1949—studied chronic illness among the indigent or medically indigent, either basing their estimates of the size of the problem on the National Health Survey rates applied to the respective state populations or utilizing the prevalence figures developed by Jarrett or by Bigelow and Lombard, also applied to the local population. Pioneering local studies of chronic illness prevalence were made in Cleveland, Pittsburgh, St. Louis, and Washington, D.C., in the early 1940's, utilizing National Health Survey rates. TECHNIQUES OF STUDYING MORBIDITY IN THE GENERAL POPULATION Methodology

in

Sampling

The last few decades have seen advances in methods of scientific inquiry in many fields related to morbidity surveys. Major emphasis has been on the development of new theory and on the practical application of sampling, rather than on complete coverage surveys. Probability samples, in which every unit in the population of people or things has a known probability of being selected for the sample, have been widely utilized. Use of this type of sample permits calculation of the amount of error which may be expected from sample coverage rather than complete coverage, improves the reliability of data, and reduces costs. Experience 20 Jarrett, Mary C. Chrpnic Illness in New York City. New York, Columbia University Press, 1933. 21 Bigelow, George H., M.D., and Lombard, Herbert L., M.D. Cancer and Other Chronic Diseases in Massachusetts. New York, Houghton Mifflin, 1933.

THE PROBLEM OF CHRONIC ILLNESS

15

with interview surveys in many fields of inquiry has contributed to improvement in techniques for collecting information about morbidity. Methods

of

Interviewing

Progress has been made also in the methodology of household interviewing. It is known that there are errors of both overreporting (reporting of health conditions which do not exist) and of underreporting (failure to report health conditions which do exist), and this knowledge has been refined to the point of identifying many of the sources of error. In a survey which uses lay interviewers to interview one person about his health and that of members of his household, the sources of error include the following: 22 1. The person with disease has had no symptoms, and is not aware of the disease. 2. The person has had symptoms but has not had medical attention and does not know the name of the disease. 3. The person has had medical attention but a diagnosis was not made, or, if made, not conveyed to the patient or was misunderstood by the patient. 4. The person knows the name of the disease but has not given the information to the person who is the respondent in the interview. 5. The respondent in the interview has not understood the information given him by the person—usually another family member—with the disease, has forgotten it, considers it not worth reporting, thinks that the interviewer wouldn't want to know about it, or conceals the information from the interviewer for any of several reasons (considers it too personal, considers it derogatory, is too hurried to take the time, etc.). 6. The respondent gives information about a disease which existed prior to the period of time about which information is sought. 7. The respondent provides the information but the interviewer doesn't record it, or records it incorrectly. 8. The interviewer doesn't ask the questions which he is instructed to ask, or asks them incorrectly. Various techniques have been developed to reduce the amount of error from some of these sources. Today, interview surveys customarily systematize the collection of information in such ways as specifying the exact words which are to be used in asking the questions and the procedures the interviewer must follow if a respondent does not understand 22

Adapted from Cobb. Op. cit.

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PERSPECTIVE

a question. For example, it has been found that when there is a problem of understanding, the best first attempt at solution lies in repeating the question exactly as it was put originally. Only when this fails should the interviewer adapt the wording to allow for such impediments to understanding as language barrier, limited mental capacity, or disinterest. "Structuring" of interviews in this fashion produces more reliable results than can otherwise be expected. Differences in the information secured by different interviewers are reduced, both because the coverage of the subject matter is more nearly complete and because there is less chance for an interviewer to pursue and get more nearly complete information on matters of particular interest to him than on other matters. Instructions to interviewers to record the response in exactly the words used by the respondent—with the omission of completely extraneous material when this can be identified by the interviewer—reduces the tendency of interviewers to record their own reactions to the information given, rather than the information itself. Planning for a survey of the general population must consider whether each person covered by the survey should be interviewed, or whether one person may be interviewed for himself and all other members of the family or the household as well. Little information was available in 1950 on differences in completeness and accuracy of the data secured by the two techniques. Interviews with each person are considerably more expensive than interviews with one person for each household. The information about health is probably more nearly complete and accurate, however, if secured from each person rather than from a spokesman for the family. Most of the surveys described earlier used an initial interview to identify members of the household; to record age, sex, color, and other characteristics; and to record information about the health status of each member either at the time of the interview or during a specified prior period. Subsequent interviews covered the illness experience of members of the household during the interval between interviews. It was found "that the succeeding interviews secured information about some health conditions which could have been but were not reported in the initial interview." Related to consideration of using single or repeated interviews is the question of the period of time for which information about health is requested. It is axiomatic that recent events are recalled more completely than events long past but that some past events, because of their impressive character, are more completely recalled than less impressive recent

THE PROBLEM OF CHRONIC ILLNESS

17

events. For example, information is reported more completely about illness requiring a long period of hospitalization than about nonhospitalized illness.23 Hospitalized illness during the past year, for example, may be more completely reported than some minor illness which occurred during the past month. Conclusive information regarding the period of time for which recall is most nearly complete and accurate is not available, and the period of time for which recall is best probably differs among health conditions. Because of the usually continuing nature of chronic conditions and the disability associated with them, information covering a long time period is needed to give a picture of the course of the disease. A short time reference is more suitable for short-term illnesses and nondisabling health conditions. Questions about illness in an interview may be either general or specific. One may ask whether a person is ill today, or was ill yesterday, or was ill during any particular period of time, and whether a person has any continuing ailment, chronic condition, impairment, etc. On the other hand, one may ask whether a person has heart disease, arthritis, or diabetes. The former method has the advantage of being all-inclusive in its interest; the latter has the advantage of directing attention to specific conditions, whether or not they are causing illness. Many surveys have included both the general and the specific questions. Experience indicates that additional questions at the end of an interview about health, such as "have you been to see a doctor," or "is there anything else," elicit reports of health conditions not given in answer to earlier questions. Despite such advances as those discussed here, however, the methodology of interviewing has not progressed as satisfactorily as has that of sampling, and much remains to be learned. For example, the magnitude of errors in reporting is not known, even though the source of error may be understood. In addition to errors in reporting and recording, some health conditions are not recorded because of deficiencies in the questions asked. These lacks may result from faulty questionnaire design with regard to coverage of some types of health conditions, or from questions which are ineptly phrased or which use terms not understandable to the respondent. Because of the deficiencies which still exist in interviewing methodology, experts recognized that for many purposes morbidity data from interview surveys must be supplemented by precise and more nearly Belloc, Nedra B. "Validation of Morbidity Survey Data by Comparison with Hospital Records." Journal of the American Statistical Association 49:832-846, December 1954.

PERSPECTIVE

18

complete data gathered by other techniques. The Subcommittee on National Morbidity Survey of the National Committee on Vital and Health Statistics included the following statement in its report: 24 The national survey would not meet all of the most pressing needs for morbidity statistics unless it is supplemented by special studies. The most important special studies are those designed to obtain data on undiagnosed and nonmanifest diseases by means of physical examinations of a sample of the United States population. Other

Techniques

Some household surveys have taken advantage of the morbidity information available from other sources to add to, or to check the validity of, data provided by the survey. The sources most frequently used are physicians' and hospitals' records of illnesses for which care has been given. One of the problems encountered in a check of these medical records is making sure that the illness about which information is being sought is the same illness for which care was received. The information secured from a respondent in an interview must include not only the name and address of the physician or hospital providing care but also the dates on which care was given. However, a great deal of specific information about the illness, though an aid in identifying it, may influence the report received. In particular, it has been found that giving the physician or the hospital the respondent's description of the illness—in either diagnostic or symptomatic terms— increases the likelihood that the interview report will be confirmed. Other sources of information which can be used to supplement interview data are the records of school health programs, of temporary disability insurance programs in the few states which operate these programs, and of absenteeism from work. A recently contrived method designed to either supplement or substitute for the household interview is the illness diary. Some surveys are experimenting with this device in an attempt to provide for day-by-day recording of illness data and presumably thereby to increase the completeness of reporting. USEFULNESS AND LIMITATIONS OF EXISTING MORBIDITY DATA

As a result of prior studies there existed in 1950 certain data that were being used to estimate the size of the problem the Commission had been 21

Proposal

for Collection

of Data

on Illness

and Impairments:

United

States.

A

Report of the Subcommittee on National Morbidity Survey, U.S. National Committee on Vital and Health Statistics. PHS Publication No. 333. Washington, D.C., Government Printing Office, 1953.

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19

created to study. However, the limitations of all these data—at least for the Commission's purposes—were highly significant. Much of the material was old in terms of advances in survey techniques. The development of methodology described above reduced the value of studies which had been made without benefit of these modern techniques. Much of the material was also old in terms of subsequent medical progress. In addition, certain specific qualifications lessened the current usefulness of the material. For example, the National Health Survey reflected conditions during depression years and before the discovery of modern antibiotic drugs and many new surgical techniques affecting the prognosis of certain chronic conditions. From the Commission's point of view, many of the local studies suffered from one or both of two types of limitations: they were focused on a particular segment of the population and their findings could not be applied to the general population; or they used rates derived from studies made elsewhere, thus compounding a variety of errors and raising the question of applicability of rates from one community to another. In the latter years of the 1940's the Commission, in reviewing 23 local studies, found that 15 had applied the results of surveys made previously in other localities. The most recent data (from the February 1949 and September 1950 Current Population Survey) did not reveal the cause of disability; they measured the severity of a disabling illness only by the informant's statement of the length of disability prior to the day of interview; and they did not include children under 14 and persons aged 65 and over. The resulting lack of information posed some problems pointed out in the report; for example, that "the persons who have been disabled longest are not necessarily the most severely ill from the standpoint of impaired health or chances of recovery." An all-important characteristic of morbidity data available on the general population as of 1950 was that the degree of completeness and accuracy of the material had not been ascertained. Some surveys had indeed checked household interview reports against physicians' and hospitals' records to determine accuracy and, to a lesser degree, completeness of reporting. But obviously, medical records can provide information only on illnesses which were medically attended. In no survey had there been a thorough investigation of disease which existed but was not reported in the interviews. After considering the available morbidity data, the Commission real-

20

PERSPECTIVE

ized that any chronic disease program charted for the future would eventually suffer to the degree that its base was faulty. It could only conclude that at mid-century a valid statistical basis for national planning did not exist. THE COMMISSION'S DECISION TO CONDUCT A SURVEY

At the second annual meeting of the Commission in May 1950, Dr. Morton L. Levin, then Director of the Commission, recommended that the Commission authorize the conduct of a "definitive survey in at least two communities—urban and rural—to determine the prevalence of chronic illness and the quantitative needs for services for the prevention, control and care of chronic illness." Dr. Levin told the Commission members that "in planning to meet the various needs for the prevention, control and care of chronic illness there is an evident lack of quantitative data regarding (a) the prevalence of chronic illness by diagnosis, by degree of disability and by types of care needed . . . and (b) the number and kinds of facilities which would be required to furnish the full amount and kinds of care indicated for chronic illness." Some of the limitations of existing data from earlier studies were set forth, i.e., that much of the data was out-of-date; that the earlier studies had not been planned to include data on diagnosis, extent of disability, or need for care; and that the accuracy of morbidity data unvalidated by medical appraisal is open to serious question. A further limitation on existing information was highlighted by one of the major characteristics of many chronic diseases—their insidious onset with no symptoms recognizable to the victim until the disease is well advanced. This stealthy approach has the effect of devaluing morbidity data based on information obtained by interview since the data reflect the existence of only those diseases of which the respondent is aware. A measure of the true prevalence of disease in the population would include all conditions detectable by the best available techniques appropriate to the purpose. Such a count would be useful as an accurate measure of the size of the problem and would also be important to any consideration of the prevention of disease. Dr. Levin was convinced that the Commission needed better data than were available. He also felt that the Commission, as a part of its responsibilities, had an obligation to produce current, accurate, quantitative data on chronic illness that could be used by others in future planning. In addition, the Commission's staff had become aware, in the first

THE PROBLEM OF CHRONIC ILLNESS

21

few months of operation, of the widespread demand for a tested methodology for conducting a community survey of chronic illness. The experience of many of the communities that made the studies discussed earlier in this chapter indicated the need for a methodology that would include current information on prevalence rates and indices for measuring needs for the various types of care. Moreover, translation of morbidity data into needs for service, and translation of the "needs" into estimates of the personnel and facilities required to provide services for prolonged illness are complex and difficult procedures. They must be based on medical judgment regarding diagnosis and the type and potential value of treatment and on assumptions regarding the organization of personnel and facilities. Because of its temporary existence and limited resources the Commission considered that, in general, its proper role in research was defining the research needed, determining what organizations or agencies should most appropriately engage in specific aspects of this research, and stimulating them to do so. At the same time the Commission agreed with Dr. Levin's view that a definitive study of the size and nature of the chronic illness problem was an undertaking on which the Commission might well build many of its future recommendations, and that, consequently, the Commission's staff would need to be close to the study and retain control of it to assure its being done in such a way as to accomplish the Commission's purposes in initiating it. The direct sponsorship of such a study was seen as highly compatible with the Commission's stated objective "to define the problem" of chronic illness. The staff of the Commission, therefore, was instructed to obtain funds, make plans, and carry out the study. Objectives

of the

Study

The general objectives of the study were those suggested by Dr. Levin. A definitive survey was to be made in at least two communities—one urban and one rural—to determine the prevalence of chronic illness and the quantitative needs for services for the prevention, control, and care of chronic illness. The specific objectives of the total project, as set forth in an early application for funds to support it, were: 1. To obtain estimates of: a. Prevalence of chronic disease by diagnosis, measured at a point in time by a complete diagnostic examination, and variations in prevalence associated with age, sex, color, economic level, and other significant social and economic factors.

22

PERSPECTIVE

b. Prevalence of illness and disability resulting from chronic disease by diagnosis, degree and duration of disability. c. Prevalence of nonmanifest or asymptomatic chronic disease, obtained through detection procedures including the multiple screening technique. This information was expected to give emphasis and direction to preventive programs and was cited as information never before obtained for the general population. It was intended to provide a measure of the extent to which present methods are successful in bringing persons under care in the very early stages of disease when treatment can be most effective in preventing or delaying the progression of disease and the onset of illness and disability. d. The rehabilitative potential of chronically ill and disabled individuals. e. The needs for facilities and services for treatment and rehabilitation of the chronically ill in terms of hospital care, home care, nursing home care, and domiciliary care. 2. To provide for the testing and evaluation of: a. New and more thorough methods for studying the magnitude and nature of the chronic disease problem. b. The multiple screening process. The rationale for conducting studies in a rural, agricultural area with limited medical services and facilities and in a highly concentrated, industrialized urban area was to provide a measure of the difference, if any, in the prevalence of chronic disease which might be associated with differing environments. Similar study methods were to be used in each area. It was believed that the information gathered in the two localities would be useful and applicable to other communities. Recognizing that the two communities selected are not "typical" in that no community can be absolutely typical of other communities, it was reasonable, nevertheless, to have as an objective the assembly of reliable data about a locality and the setting forth of that data against background information comparing that locality with other areas in regard to significant demographic factors. Launching the Study On October 31, 1950, the Commission was notified that the Surgeon General had approved a research grant from the National Institutes of Health. This grant, in the amount of $10,000, was intended to enable

THE PROBLEM OF CHRONIC ILLNESS

23

the Commission to proceed with the essential planning stages of the project, pending the selection of locales and the formulation of the specific method of approach. The Commission was informed by the Executive Secretary of the Public Health Study Section, Division of Research Grants, National Institutes of Health, that the two studies were "of importance to a large number of groups actively interested in the chronic disease field and . . . the support of agencies in addition to the Public Health Service not only seemed appropriate but highly desirable." In February 1951, the Board of Directors of the Commission authorized the participation of the Commission in a general survey of health conditions in Hunterdon County, New Jersey. Dr. Ray E. Trussell, Director of the Hunterdon Medical Center, had invited the Commission to consider Hunterdon County as the site for the proposed rural study. He had pointed out the favorable local situation—the fact that the county was in process of developing an over-all health and medical care program of high quality—and that the Commission's objectives in making the study fitted in with the broader objectives of a contemplated health inventory of the county. The study was made in the period from June 1951 to July 1955. It was sponsored jointly by the Hunterdon Medical Center and the Commission. The field work for some phases and the statistical processing and analysis were planned and carried out by the National Opinion Research Center with the assistance of the New Jersey State Department of Health. The study was financed almost entirely by the Commonwealth Fund; the Commission's staff devoted a portion of the funds obtained under the planning grant from the National Institutes of Health to the cost of planning the Hunterdon study since basic planning for both the rural and the urban studies had necessarily to be done before either could be launched. Because of the availability of funds and the momentum of developing events, the rural study then got under way sooner than the urban. The findings of the Hunterdon study are fully described in another volume of this series.23 Differences

between

the Rural

and

Urban

Studies

There were differences between the Hunterdon County and the Baltimore studies—differences in approach, differences inherent in the geographic 31 Chronic Illness in a Rural Area, Vol. Ill of this series, Chronic Illness in the United States.

24

PERSPECTIVE

and social situations of these two communities, and differences which were administratively unavoidable or were considered desirable. In Hunterdon County the study was carried out in a rural setting where intense interest in the establishment of effective health services was current. It was identified as an aspect of the establishment of the new services. Household interviewing was done by local school teachers during 6 weeks of the summer vacation months in 1951. Previously, school children, teachers, and other volunteers had participated in the preparation of the maps and listings from which the original sample was drawn. The medical, nursing, and social appraisal, which involved several interviews, and the multiple screening tests were conducted at a new community medical facility—gleaming, modern, comfortable, and convenient. The professional staff involved were employees assigned on a full- or part-time basis to a project whose results could be expected to provide them with valuable data for their future work in the county. Solicitation of cooperation in the various phases of the study was largely in the hands of volunteers who were well-known and persuasive local figures. In Baltimore the study was carried out in a great metropolitan area by a national agency with no local identification. The household interviewing was performed in a 52-week period by interviewers employed by the Bureau of the Census for that purpose. The collection of information for the medical, social, and nursing appraisal was performed for the Commission by a very large, internationally famous institution, The Johns Hopkins Hospital. The multiple screening tests were carried out at a center established and operated by the Commission for that specific purpose. In the Hunterdon County study the time interval between the household interview phase and the successive phases was much greater than in the Baltimore study. And, finally, since each step of the total project in Baltimore was begun after experience had accumulated in Hunterdon County, the methods used in the later study were almost inevitably adjusted to profit— and perhaps, differ—from the experience gained in the earlier project. The goal in this regard was the accomplishment of a happy medium between a desirable parallelism and improvement based on experience.

CHAPTER 2 PLAN OF THE STUDY

Step One. The Household Interview Survey Step Two. The Clinical Evaluation Step Three. Screening Step Four. The Vocational Rehabilitation Demonstration Planning the Study Choosing the Locale The Sample Minimizing Bias in Results

28 30 34 37 38 38 39 42

Chapter

2 Plan of the Study The study of prevalence of chronic illness and needs for care in an urban area was carried out in Baltimore between 1952 and 1956. Preliminary planning began in July 1952. Field work on the first phase began in September 1953, and the final field work was completed in April 1955. The study was financed by a series of grants from the National Institutes of Health 1 and also by a grant from the Commonwealth Fund. In order to accomplish the established objectives the field work of the study was planned, organized, and carried out in four phases. Omitted was one of the phases of the Hunterdon County study—the self-administered questionnaire concerning the health of the family. Otherwise the general plan and broad method of the two studies were similar. The four phases in the Baltimore study were identified as "steps" and were as follows: Step one. An interview by trained lay interviewers to obtain information about illness and disability in approximately 4,000 households, including about 12,000 people and representing a random sample of the population of the city. Step two. A "clinical evaluation" of a sample of approximately 1,000 persons. This evaluation consisted of a review of existing medical information obtained from hospitals and private physicians; a complete diagnostic examination, including all indicated laboratory tests, at a special clinic established for the purpose at The Johns Hopkins Hospital; and, for a special group, an evaluation of social, nursing, and rehabilitation needs by a team composed of a physician, a nurse, a social worker, and a vocational counsellor. Step three. The administration of a series of simple screening tests to all members of the 4,000 households who were not included in step two and who were over 16 years of age. Step four. A demonstration of rehabilitation for those persons identi1

U.S.P.H.S. Grants numbers RG2795, G3182, G4011, G4011C, RG4011(C)2. 27

28

PERSPECTIVE

fied in step two as having a vocational rehabilitation potential. The Division of Vocational Rehabilitation of the Maryland State Department of Education assumed the responsibility for this step in order to give a practical test to the process of estimating rehabilitation potential. A detailed description of the methodology employed in the study appears in Appendices Α-D. A brief general description of the plan for carrying out the various steps follows. STEP ONE.

THE HOUSEHOLD INTERVIEW SURVEY

Step one, the household canvass, was a procedure in the best tradition of the morbidity survey. In this study, however, the information derived from the morbidity survey was a means to an end, rather than the end itself. The canvass was an essential first step in obtaining the sample of persons to be intensively studied. Also, the secondary objective of testing the interview technique obviously could be accomplished only if a survey was made. In December 1952 an agreement was reached with the Bureau of the Census for that agency to carry out most of step one. The long experience of the Bureau in the collection of data proved invaluable. The contract with the Bureau included selecting the representative sample of Baltimore's population, developing the interview form, employing and training staff for the interviewing, and tabulating the data according to specifications set forth by the Commission. The sample was drawn from the population of Baltimore City. Consideration was given to drawing the sample from the "urbanized area" of the Baltimore Standard Metropolitan Area as defined by the Bureau of the Census. However, it was administratively simpler, in terms of the number of agencies to be asked for endorsement and cooperation, to confine the study to the city limits. It was also recognized that the "urban fringe," which was excluded under the final plan, was only 18 per cent of the "urbanized area," and for the purposes of this study, people living just outside the city limits might be expected to be similar to those living just inside. A sample of 3,828 addresses, one out of 80 within the city, was selected, with each address in the city having an equal chance of being chosen. The 1950 census lists, supplemented by a survey of housing not represented in the 1950 census, provided the complete list of all addresses in the city from which the selection was made. The families living at the sample addresses at the time of the interview constituted the study group; and counted as household members were hospitalized persons who were

PLAN OF THE STUDY

29

expected to return home in a short period of time. Residents of special dwelling places, i.e., residential hotels, rooming houses, and school dormitories were also sampled at the rate of one in 80. Throughout this report the term "noninstitutional population" is used to designate the sample defined by this paragraph. Medical institutions for long-term care—that is, chronic disease hospitals, nursing homes, and homes for the aged—were not included. Persons in need of long-term care frequently seek such care outside the locality in which they reside, so that a sample of residents of institutions located in Baltimore would not be representative of all Baltimoreans in long-term care facilities. Inmates of the state penitentiary, located in Baltimore, were excluded for the same reason. By virtue of exclusion of institutionalized persons from the sample there is excluded from consideration in this report a group in which the prevalence of illness and disability is high. Statistical information about a substantial segment of this group (patients in proprietary nursing homes and homes for the aged) is being published in the joint CommissionPublic Health Service report of a study conducted in 13 states, including Maryland. 2 The exclusion of persons in medical institutions for long-term care results in an underestimation of all disease. Notably it produces an underestimation of the prevalence of tuberculosis and psychiatric disease, since in Maryland, as in most states, the medical care system is such that persons with these diagnoses are usually in long-term care institutions. In order to coordinate the household interview with the other phases of the study, the 3,828 households were divided into a series of 52 subsamples, each of which was in itself a small but representative sample of the city. This procedure also provided a safeguard for the representativeness of the sample in case it became necessary to end the interviewing phase before all of the 3,828 households had been interviewed. The Census Bureau employed and trained 6 interviewers and a supervisor for this phase of the study. Each interviewer was provided with an official identification card from the Bureau and a manual prepared for training purposes. The interviewers who were selected had passed the test routinely used by the Census Bureau in securing interviewers for its own data gathering. In addition, they were chosen because they were personable and had an easy manner of dealing with the public. 2 Nursing Homes, Their Patients and Their Care: A Study of Nursing Homes and Similar Long-Term Care Facilities in 13 States. A joint project of the Commission on Chronic Illness and the Public Health Service. Public Health Monograph No. 46, PHS Publication No. 503. Washington, D.C., Government Printing Office, 1957.

PERSPECTIVE

30

Each interview was preceded by an introductory letter explaining the purpose of the study. In addition to filling out the questionnaire, the interviewer requested the householder to sign a written statement granting permission to examine existing medical and hospital records. She also gave a brief summary of the subsequent steps of the study in which the householder might be involved. The interview form, developed by the Census Bureau and the Commission for use in the Baltimore study, was based partly on experience gained in Hunterdon County. Each interviewer was required to state the questions exactly as they appeared so that answers would not be biased by leading questions. The questions were directed to the informant about himself and all persons living in the household. They were divided into questions about health conditions of yesterday, during the past 4 weeks, and during the past year. The questions were simple and forthright: Were you sick at all yesterday... ? Yesterday, did you have an accident. . . injury or poisoning? Did you feel the effects of an earlier accident, injury or poisoning? Were you sick at any time during the past four weeks? Do you have any impairments or handicapping conditions? Do you have any chronic conditions or ailments? Has anyone in the family had trouble with any of these conditions during the past twelve months? . . . or any of these symptoms? (A prepared list of 34 specified conditions and 12 symptoms was used in obtaining the answers to the last two questions.) Other questions elicited the age of the family members, their economic status, the duration of symptoms and disability, periods of hospitalization, and the existence of chronic conditions not causing illness (for example, controlled diabetes). Data on the questionnaire were so arranged as to be easily classifiable for any given period of time in terms of disabling illness, hospitalized illness, illness for which medical care was received, duration, and diagnosis. Field work on step one was completed August 27, 1954. Interviews were completed in 97.7 per cent of the occupied dwelling units selected for the sample. STEP TWO.

T H E CLINICAL

EVALUATION

Field work for step two began in November 1953. A lag of two months was established between the first interview under step one and the earliest possible date on which a member of the sample might be invited to participate in step two. Some lag was inevitable, as the sample for step two

PLAN OF THE STUDY

31

could not be selected until the completed questionnaires from step one were received. Five weeks were needed for this process, and it was expected that a few more weeks would be needed to make the necessary arrangements with the persons to be invited to participate. Approximately 10 per cent of the basic survey group of about 12,000 persons were chosen as the sample for step two. This phase was labeled the "clinical evaluation" step because of the intensive examinations involved. For operating convenience the individuals selected were identified as "evaluees." The composition of the sample of persons whose health conditions and needs for care were to be intensively studied was determined so as to assure that (a) the bulk of the evaluation effort would be devoted to persons with substantially disabling health conditions, and (b) statistically reliable data would be secured about a few of the more frequent, serious chronic diseases in addition to information about the over-all effects of chronic illness. Each individual in the household interview sample was classified into one of three groups: 1. Persons reporting maximum disability, i.e., persons who had been kept in bed or kept from their usual activities for 6 months or more during the past year, or had been in a hospital 30 days or more regardless of diagnosis, and persons who classified themselves as "unable to get around without help." 2. Persons with less disability than those in the above group, but reporting specified diseases which are—or may be—chronic. They were divided into subgroups on the basis of the following diagnoses: diabetes, diseases of the central nervous system, neoplasm, heart disease, arthritis and rheumatism, and all other diseases. 3. Persons reporting no disease or only certain short-term or nondisabling conditions such as influenza, upper respiratory infections, selected acute communicable diseases, dental caries, refractive errors. If an individual could properly be assigned to more than one of the above three groups, he was arbitrarily classified in the appropriate group nearest to the top of the list. The goal was to evaluate 1,000 persons. The number of evaluees chosen, a total of 1,292, allowed for some who, it was anticipated, would not participate. The evaluees were selected as follows: 1. From Group 1 : all of the 182 persons in the group. 2. From Group 2: of the 91 persons reporting diabetes, a 100 per cent sample; of the 54 reporting diseases of the central nervous system, a

32

PERSPECTIVE

100 per cent sample; of the 107 reporting neoplasm, a 100 per cent sample; of the 257 reporting heart disease, a 40 per cent sample, or 102 evaluees; of the 446 reporting arthritis and rheumatism, a 25 per cent sample, or 111 evaluees; of the 3,866 reporting all other diseases, a 7 per cent sample, or 265 evaluees. 3. From Group 3: of the 6,571 in the group, a 6 per cent sample, or 380 evaluees. The use of different sampling proportions for the various groups permitted the desired concentration of effort on types of cases representing significant conditions and prevalent diseases. The findings for each group have been weighted as indicated by the sampling proportion for the group, so that estimates for the total sample of 11,574 are not biased by the method of selecting evaluees. At the time of the household interview, written permission was obtained to secure additional medical information from physicians, hospitals, or clinics. The personal physician of each evaluee received a letter explaining the nature of the study, and was later telephoned by a physician on the Commission's staff who obtained pertinent information as to the nature of the illness, the resultant disability, and any medical contraindications to a clinic appointment. The telephone call, in many instances, afforded an opportunity to explain the "place" of the evaluation clinic in the existing doctor-patient relationship. Additional medical information was obtained routinely from abstracts provided by hospitals and clinics where the evaluee had been a recent patient. The evaluation clinic, instituted under a contractual agreement with The Johns Hopkins Hospital, was held three mornings a week in that Hospital's Medicine I Clinic. The Commission supplemented the staff of the clinic by providing a medical social worker, a rehabilitation counsellor (assigned by the Maryland State Department of Education), and clerical assistance. The Commission also paid for the services of the physician who was responsible for general direction of the evaluation clinic. To conduct the examinations the Hospital contributed the services of a panel of physicians specializing in internal medicine or pediatrics. These physicians were either full-time Fellows in the Department of Medicine or physicians in private practice with Hospital staff appointments, who made one or more examinations each week as a part of their assignment. At the outset, it was recognized that the Commission was entirely dependent for the success of the clinical evaluation and, consequently, the

PLAN OF THE STUDY

33

study, on the willingness of the evaluees to give their time and adjust their affairs in the interests of a physical examination which, however complete, thorough, and valuable, they might not in the least desire. The clinic, therefore, operated on an appointment basis, and the entire procedure was geared to minimum inconvenience and maximum comfort for the evaluee. A physician from the panel was assigned to each patient. He performed a physical examination and, in addition, ordered any consultations or special diagnostic tests needed to clarify the patient's medical condition and needs for care. Evaluees over 18 years of age were routinely given a 70 mm. chest x-ray, an electrocardiogram, a vision test, a pure-tone audiometer test, serologic tests for syphilis, tests for blood sugar and hematocrit determinations, and urinalysis. A dental examination was included on the theory that (a) while dental diseases and conditions are not often considered chronic illnesses they should be so classified with very few exceptions; and (b) this evaluation offered an excellent opportunity to gather information—largely lacking at the time—on the dental health status and needs of a general population. The examinations were so thorough and detailed that 3 to 4 hours were usually required for the complete clinic procedure. For younger persons some of the tests were omitted. Evaluees who were so incapacitated that they could not come to the clinic were examined at home by one of the clinic physicians, assisted by a public health nurse. Of the 1,292 persons selected for evaluation, 731 participated in the evaluation clinic at the hospital and 33 more participated through an evaluation at their homes. Information about an additional 45 persons has been included in this report. Although these people refused to participate in the evaluation clinic, the current medical data provided by their physicians and hospitals were sufficiently complete to permit analysis by the study staff. These people had in common with the clinic evaluees the fact that a thorough diagnostic study had been made owing to an illness during the year before or immediately following the household interview (step one). This total of 809 evaluees represents a response of 62.6 per cent. For each evaluee, the examining physician completed a record in which significant chronic conditions were analyzed in terms of severity, history, disabling effects, treatment and care required, and prognosis. Each record was reviewed by the rehabilitation counsellor, for the purpose of identifying those evaluees who had a potential for rehabilitation

34

PERSPECTIVE

in terms of activities of daily living, working, housekeeping, and/or school attendance. In every instance where disability existed and certain factors indicated a potential for rehabilitation, a home visit was made by the counsellor to produce a more intensive and detailed estimate of the rehabilitation potential. A random sample of the completed diagnostic examinations was chosen which included one half of the evaluees from group 1 and one half of those from group 2. The records on these persons were reviewed and evaluated from the nursing and socioeconomic viewpoints by the public health nurse and the medical social worker. Cases where this review revealed a significant health condition were thoroughly investigated by the nurse, social worker, or rehabilitation counsellor, depending on the more apparent need. Each evaluee who had been the subject of the social-nursing-rehabilitation investigation then became the focus of a discussion by a team including the physician, the nurse, the social worker, and the rehabilitation counsellor who had been associated with the case. Meeting with the staff of the Commission, the group reviewed the health status of the evaluee to: 1. Establish or confirm all existing conditions. 2. Estimate the need for care, in terms of services and facilities, of the patient. 3. Estimate the rehabilitation potential of the patient and the rehabilitation services required. 4. Insofar as was practical, pursue the question, "What preventive medical services could have been profitably applied to this patient during the course of the illness which would have averted, halted, or delayed the progress of the disease?" 5. Evaluate the socioeconomic problems which had been obstacles to treatment and care of the patient. STEP THREE.

SCREENING

The "screening clinic," as it was called, was held in Bennett Hall, the auditorium of the Maryland State Department of Health in Baltimore, which had been lent to the Commission for the purpose. Bennett Hall is conveniently located just outside the downtown area; a large, free, parking lot adjoins the building. In this set-up the Commission established a staff consisting of a physician, 2 full-time public health nurses, a clerical supervisor, 11 technicians, 11 clerk-typists, 5 field interviewers, and a janitor. For a period of several months prior to the opening day a health educator was also employed.

PLAN OF THE STUDY

35

The primary purpose of the Commission in undertaking this phase of the study was to detect evidence of chronic illness additional to that reported in the household interview. Such cases would be expected to include (a) conditions that people do not yet know they have since either no symptoms or no recognizable symptoms have been noted for which medical advice would be sought, or (b) conditions such as venereal disease which are not reported because of the social stigma frequently associated with them. The first question to be answered in planning for the screening test was, "For what conditions shall we screen?" In practice, however, this question was not answered until a second question had been considered, "For what conditions are screening tests available?" Adequate screening tests appeared to be available for obesity, diabetes mellitus, hearing deficiencies, visual acuity, hypertension, heart disease, tuberculosis, lung tumors, renal disease, anemia, syphilis, and some heart diseases. No test was employed that required the patient to disrobe, required administration by a physician, or required over 5 minutes of time. In addition to screening tests for the above conditions, a dental examination was scheduled—for the same reasons that it was included in the clinical evaluation. The dental examination at the screening clinic was made possible through the enthusiastic cooperation of the Bureau of Dental Care in the Baltimore Health Department and the Division of Dental Public Health, Public Health Service. Invitations to attend the screening clinic were addressed to the 6,967 members of the sample households who had not been invited to participate in step two and who were over 16 years of age. Just over 2,000 persons, or 29 per cent of the total invited, attended the clinic. While it was not anticipated that all 6,967 invitees would come, the response was far below the expected number. Screening clinic procedure was as follows. On arrival at the clinic, as a part of the test for diabetes (modified glucose tolerance test), the screenee was given an orange-flavored, carbonated drink containing 50 gm. of glucose. His height and weight were recorded. He filled in a brief questionnaire designed to obtain information as to whether he had any of the conditions for which he was going to be tested and whether he was currently under medical care for these. The questionnaire also sought to elicit information about symptoms attributable to heart disease or diabetes. The dental examination was the next procedure. The screenee then went on to a booth where electrocardiography and blood pressure determinations were performed. The EKG electrodes were applied to the

36

PERSPECTIVE

two arms and left leg and recordings of the 3 standard and the 3 unipolar limb leads were made. (These records were interpreted by a cardiologist at a later date, and if they could not be definitely classified as normal or abnormal, the screenee was invited to return for chest leads.) Visual acuity was next tested, using the American Optical Company Sight Screener. Following this, the screenee was taken to a sound-proof booth where a pure-tone sweep-check test for hearing was carried out. (An individual who failed in this test was given a more thorough hearing "threshold" test before leaving the clinic.) The 70 mm. chest x-ray film was then taken. By that time, from 30 to 50 minutes had elapsed since the screenee had taken the glucose drink. The exact interval was recorded and a urine specimen was obtained and tested for sugar and albumin. In the final testing station—and an estimated hour after the screenee had taken the glucose drink—a sample of blood was taken from a vein. A portion of the blood was kept for the serologic tests for syphilis which were done a few days later. The remainder was used to determine the presence of anemia and diabetes. These results were available 10 minutes later. Those test results which were immediately available were recorded in code form on the screenee's invitation card, which he carried with him through the entire procedure. This card was handed to one of the public health nurses, who interviewed each person before he left. This interview was designed to answer questions; to prepare each screenee for the type of letter he was likely to receive 3 or 4 weeks later; to stress the need for a visit to his personal physician if the letter should advise this; and to make it clear that the results of the tests would be sent to his personal physician. About 4 weeks after the clinic visit, a complete copy of all the test results, including a copy of the EKG tracings, was mailed to the personal physician indicated by the screenee. Two days later, one of several letters was sent to the screenee. When the tests were completely negative, or when only a minor abnormality was present, the letter stated this fact and did not urge a visit to a physician. When a serious abnormality appeared to be present, the letter stated that a "condition" appeared to be present for which the screenee should consult his family physician. The Follow-Up

Procedure

How to follow up the referral of suspicious situations so as to encourage the screenees to seek medical advice, and further, how to find out what

PLAN OF THE STUDY

37

the diagnostic examination reveals are two of the most perplexing administrative problems in screening clinic operation. Both are fundamental to any judgment as to the value of the whole process, when the objective is other than for purely health education purposes. About 3 weeks after the letters urging a physician visit had been mailed, a follow-up letter was sent to the screenee soliciting his help in evaluating the clinic and asking him to complete a simple questionnaire. The primary purpose of this communication was to find out whether he had, in fact, visited his physician and what he had understood his physician to say concerning the results of the screening tests. If the screenee had not returned the questionnaire within 2 weeks, he was telephoned for the desired information. When no telephone was listed, a home visit was made. Of the 607 individuals who were urged to see their physicians because screening had revealed abnormalities considered serious enough to justify medical advice, 393 reported that they had done so. When these 393 reported that they had seen their physicians about the results of the screening tests, a questionnaire listing again the abnormalities found at the clinic was sent to the physicians and they were asked to complete the form by indicating their diagnoses. The physicians returned 232 usable questionnaires. On an additional 119 a staff physician obtained the desired information by telephone. STEP FOUR.

THE VOCATIONAL REHABILITATION

DEMONSTRATION

By the agreement with the Division of Vocational Rehabilitation of the Maryland State Department of Education, individuals identified by the team of professionals (step two) as having a rehabilitation potential for remunerative employment were to be rehabilitated to the extent that facilities of the community permitted and that the cooperation of the individuals could be obtained. This group included those capable of employment outside the home, housewives, and those for whom the objective was home-bound industry. In this group there were 36 individuals. They were assigned to the study's vocational rehabilitation counsellor for intensive case work and study to test the reliability of the method of estimating rehabilitation potential and to measure the extent to which persons with chronic illness in a random sample of an urban population can be rehabilitated. Because this step of the study was a demonstration requiring an extended period of time, complete results were not available for incorporation in this report. Such analysis as was available appears in Chapter 7.

38

PERSPECTIVE PLANNING THE STUDY

Five advisory committees3 assisted in planning the various phases of the study. A General Advisory Committee was organized in October 1952 and included representatives of the city's two medical schools, The Johns Hopkins University School of Hygiene and Public Health, the state and city health departments, the Baltimore Medical Society, the Maryland State Board of Health, and the Maryland State Planning Commission. An Advisory Committee on Selection of the Sample, under the chairmanship of Dr. Lowell J. Reed, then Vice President of The Johns Hopkins University and Hospital, was composed of experts on sampling. It met in September 1952 to assist in making some basic decisions about the sample to be used. The third advisory group was concerned with methods of clinical evaluation. This committee was called together in November 1952 to advise the staffs for both the Baltimore and Hunterdon County projects on the somewhat unique problems to be faced in executing step two. Dr. Howard Rusk headed this committee. The fourth advisory group was composed of representatives of the University of Maryland School of Dentistry, the Maryland State Board of Health, the Public Health Service, and the dental divisions of the state and city health departments. This group met twice in 1953 to advise on proposals to include questions concerning dental care in the household interviews and dental examinations in the clinical evaluation and the multiple screening steps. The fifth group consisted of 9 Baltimore physicians who met twice in 1954 to advise on plans for conducting a multiple screening project in the city. CHOOSING THE LOCALE

Baltimore was selected as the urban area in which to make the study after receipt of an invitation from the Chronic Disease Subcommittee of the Committee on Medical Care, Maryland State Planning Commission. The Subcommittee was interested in having the study done in Baltimore primarily because it also was engaged in gathering information on chronic disease as a basis for an extensive expansion of Maryland's facilities and services for the chronically ill. The findings of such a study as planned by the Commission on Chronic Illness would undoubtedly be most useful to the Committee, the state planning commission, and the state government as a whole in implementing the expansion program. * For a complete list of members of these committees, see Appendix J.

39

PLAN OF THE STUDY

From the standpoint of successful operation of the field work for the study, the auspices offered to the Commission by the Baltimore invitation were most attractive. Local prestige that could be expected to create a favorable atmosphere of cooperation was much to be desired. The participation of a cross-section of the general population would be vital, to say nothing of the cooperation required from the local members of the medical profession. Approval of the study plan was given by the Council of the Medical and Chirurgical Faculty of Maryland—the state medical society—on April 27, 1953. The plans for the study were published in the Maryland State Medical Journal in June 1953. On July 29, 1953, the officers and executive committee of the Baltimore City Medical Society approved the study plans, and on September 8,1954, the president and executive council of the Baltimore City Dental Society approved the study and specifically endorsed the incorporation of the dental examinations in the clinical evaluation and multiple screening steps. THE SAMPLE

Perhaps no group of the population can be said to be "typical" of any other group. Sweeping generalizations can probably be made that are so sweeping and so general that they must be accepted through the sheer breadth of their claims. Except for such generalizations, however, purists can demolish claims of representativeness in progressively specific situations so that ultimately each individual is indeed an individual, atypical of anyone else. It is probably significant, from the sociologie standpoint as well as the patriotic, that the one universally accepted and revered symbol for all is an "unknown" soldier. People cannot point out how he is different from them and, thus, not representative. In presenting the findings of the study of the population of Baltimore no claims can be made for the absolute significance of these findings for the populations living elsewhere in the United States or even only in other urban communities, although it is thought that some useful conclusions can be reached by a national audience if only on the basis of "profiting from the experience of others." Actually it is felt that a far greater amount of significance can and must be drawn from these findings. At the time of the Baltimore survey, a study of the depth and intensity of this project seemed neither practical nor likely for the total population of this country or many of its major urban communities in the foreseeable future. It is confidently believed that the findings of this study both in Baltimore and in Hunterdon County will serve many purposes for many individuals

40

PERSPECTIVE

TABLE 1.

Populations of Baltimore, all cities of 100,000 or more, and the continental United States, 1950, by age, by color, and by annual family income Percentage distribution Age, color, and income All ages Under 15 15-34 35-64 65 and over Median age

Baltimore

Cities of 100,000 or more

Continental United States

100.0 23.7 31.9 37.1 7.4

100.0 22.4 31.1 38.4 8.1

100.0 26.9 30.3 34.6 8.2

31.7

32.9

30.2

White and nonwhite White Nonwhite

100.0 76.2 23.8

100.0 86.8 13.2

100.0 89.5 10.5

All incomes Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over

100.0 33.8 37.6 17.2 11.4

100.0 31.7 36.8 19.1 12.5

100.0 38.6 35.0 16.4 10.1

$2,817

$2,995

$2,619

Median income Source: U.S. Bureau of the Census.

and groups, especially for students of the problem of chronic illness and for those engaged in community planning. Table 1 presents a comparison of the population of Baltimore with the population of the United States and of cities with over 100,000 population. This comparison is by age, color, and annual family income. Baltimoreans apparently differed very little from their fellow Americans in respect to age distribution and annual family income. They differed even less from the residents of other large cities. The percentage of Baltimore residents aged 65 and over was slightly less than in other cities, but even here the percentage distribution by age was close to that of the population of the continental United States. By far the most marked difference between Baltimore's population and that of the United States was the higher proportion of nonwhites in the city. The presence of a large Negro population is a well-known, wellrecognized, and expected characteristic of a major American city with a comparatively long history tied in with the economy of the southeastern part of the country. There is nothing surprising in the fact that, in 1950, 24 per cent of Baltimore's population was nonwhite4 as compared with 1 1 9 5 4 estimates by the Baltimore City Health Department placed the percentage closer to 27.

PLAN O F T H E S T U D Y TABLE

2.

41

Comparison of the population of Baltimore and the household survey sample, by age and by color Household survey sample1 Age and color

Number

Per cent

Population of Baltimore* Number

Per cent

All ages Under 15 15-34 35-64 65 and over Age unknown

11,574 3,135 3,219 4,329 870 21

100.0 27.1 27.9 37.5 7.5

966,109 258,705 274,718 358,947 73,739

100.0 26.8 28.4 37.2 7.6

White and nonwhite White Nonwhite

11,574 8,388 3,186

100.0 72.5 27.5

966,109 708,151 257,958

100.0 73.3 26.7

1 Persons whose age was unknown are included in the total number but excluded from the percentage distribution. 2 As estimated July 1,1954, by the Baltimore City Health Department.

11 per cent of the population of the country as a whole, and 13 per cent in all cities with over 100,000 population. The proportion of Baltimore households with incomes above the $4,000 level was slightly smaller than in all cities but was slightly larger than for the continental United States. All in all, insofar as the foregoing characteristics are concerned, the population of Baltimore differed significantly from the population of all larger communities only in respect to the higher proportion of nonwhites living in the city. This characteristic of the population, of course, was recognized throughout the planning and execution of the study. Table 2 presents a comparison of the age and color distribution of the 11,574 persons included in the household interview step with the best available estimate of the population of Baltimore. This comparison shows no significant differences in the ages of the two groups, or in the proportion of nonwhite persons in the two groups. Similar, too, was the age distribution of whites and nonwhites in the population of the city and in the household interview sample. The clinical evaluation sample was selected in such a way that adjustment of the data for differences in sampling proportions of the various groups and for differences in the proportions participating could be accomplished through the application of weights. This system of weighting permits expression of the findings of the clinical evaluation in terms of the 11,574 persons surveyed in step one who have been shown to be very similar to the total population of the city in terms of age and color. The various weights applied employed one decimal place for accuracy. For convenience in processing, the decimal place has been carried in all

42 TABLE 3.

PERSPECTIVE Comparison of clinical evaluation sample (weighted and unweighted) and household survey sample, by age, by color and by sex Age, color, and sex

Persons Unweighted

Number of persons

809

evaluated Weighted 11,579.2

Percentage

Household survey sample 11,574

distribution

All ages Under 15 15-34 35-64 65 and over

100.0 20.9 19.7 46.4 13.1

100.0 27.1 27.7 38.1 7.0

100.0 27.1 27.9 37.5 7.5

White and nonwhite White Nonwhite

100.0 70.7 29.3

100.0 72.4 27.6

100.0 72.5 27.5

Both sexes Male Female

100.0 45.5 54.5

100.0 47.4 52.6

100.0 47.4 52.6

tabular computations, but is not intended to indicate an extremely high degree of accuracy. In text discussions, the figures have usually been rounded to the nearest whole number. Table 3 compares the characteristics of the 809 persons evaluated, unweighted and weighted (11,579.2), with the 11,574 originally surveyed in the household interview. It shows that after weighting, the 809 evaluees were distributed almost identically, by age, color, and sex, with the household survey sample, which in turn was distributed almost identically with the population of the city. The 809 persons are representative of the noninstitutional population of Baltimore to the extent that their health characteristics (for each age-sex-color group) approximate the health characteristics of nonparticipants (for each age-sex-color group). MINIMIZING BIAS IN RESULTS

Despite intensive efforts to secure the participation of all the sample households in the interview step, and of all persons selected for clinical evaluation and invited for multiple screening, the proportion participating—called the "response rate"—differed substantially among the various steps. The analysis of the response rate for multiple screening and its significance for that phase are presented in the sections of this volume devoted to the screening clinic. In the household interview phase the response rate was 97.7 per cent. The nonresponse of 2.3 per cent comprises the 2.0 per cent of the households whose occupants could not be located for interviewing and the

PLAN OF T H E STUDY

43

0.3 per cent whose occupants refused interview. Dwelling units which had been demolished or were vacant are excluded from these figures. The response rate for the clinical evaluation was 62.6 per cent.5 Surprisingly, the rate was not markedly different in any consistent pattern among the groups into which the household interview sample had been divided for selection of the clinical evaluation sample. Persons reporting maximum disability, those reporting less disability but some condition which could be chronic, and those who were free of disabling conditions responded in approximately equal proportions. There were, however, substantial differences in the response rate by age, color, and sex—three characteristics which are known to affect health and which were accurately reported in the household survey. The response rate was high for children and low for the aged. Nonwhites participated in much larger proportions than whites, and males in slightly larger proportions than females. When a response rate is substantially below 100 per cent, the question arises as to whether participants differ from nonparticipants in some way which is important to the study—in this instance in ways related to health. It becomes necessary to know as exactly as possible how well the participants represent the entire sample. Conversely, it becomes necessary to know to what extent and in what ways they are not representative, and thus the degree and manner of bias that their nonparticipation introduces. The household interview response rate was so high that any bias which existed was negligible. This was not true, however, of the clinical evaluation phase. With a nonresponse of 37.4 per cent it became necessary to consider the question of bias most carefully. In carrying out this procedure the study had the important advantage of the availability of all the data from the household survey for both participants and nonparticipants. The information about the nonparticipants was used in attempting to appraise bias due to nonresponse. Chronic conditions were reported in interviews at a somewhat higher rate (9 per cent) and days of disability were reported at a slightly lower rate (about 2 per cent) for the 809 evaluees (weighted) than for the 5 This rate is similar to the experience of other studies which included an intensive effort to obtain the participation of the general population in a medical examination. See Rubin, Theodore, Rosenbaum, Joseph, and Cobb, Sidney, M.D. "The Use of Interview Data for the Detection of Associations in Field Studies." Journal of Chronic Diseases 3:253, September 1956. Also Trussell, Ray E., M.D., Elinson, Jack, and Levin, Morton L., M.D. "Comparisons of Various Methods of Estimating the Prevalence of Chronic Disease in a Community—The Hunterdon County Study ."American Journal of Public Health 46:173-182, February 1956.

44

PERSPECTIVE

total survey sample. Chronic conditions were reported at a slightly higher rate for the 809 evaluees (weighted) than for the total survey sample for some important diagnoses—neoplasm, 13 per cent; diabetes, 6 per cent; and hypertension without heart involvement, 4 per cent. For some other diagnoses, the 809 evaluees (weighted) reported a slightly lower rate than did the total survey sample—arthritis and rheumatism, minus 1 per cent; and all heart disease, minus 7 per cent. The study staff concluded that if the 809 persons evaluated were a biased group, the amount of bias was probably small, and that the interview data available did not establish with certainty the direction of bias though it seemed likely to be in the direction of a little more disease among the evaluees than among the total survey sample. The data supporting this conclusion are described in detail in Appendix C, as are the processes of weighting intended to reduce bias stemming from various sources, including nonresponse.

PART Π

The Volume and Character of Chronic Disease (Clinical

Findings)

CHAPTER 3 PREVALENCE OF ALL CHRONIC DISEASES AND DISABILITY IN THE POPULATION

Prevalence of Chronic Disease Distribution of Chronic Disease Severity of Chronic Disease Substantial Chronic Conditions Characteristics of Substantial Chronic Conditions Disabling Effects of Chronic Conditions Persons with No Chronic Conditions

49 54 55 56 57 62 70

Chapter

3 Prevalence of All Chronic Diseases and Disability in the Population PREVALENCE OF CHRONIC DISEASE

Nearly 1,600 chronic conditions per 1,000 population, or 1.6 conditions per person, were diagnosed in the clinical evaluation of a sample of the noninstitutional population of Baltimore. This rate is far above the rates derived from earlier studies which used less exhaustive methods. It is, for example, nearly 8 times as great as the rate of 204 chronic conditions per 1,000 persons derived from the studies in the Eastern Health District of Baltimore1 which employed monthly household interviews over the 5-year period 1938-1943. The earlier studies which produced the lower rates differed, it is true, from the present one in such important aspects as objectives and methods.2 Because of this they would not be expected to produce results comparable with those of the Baltimore study. Nevertheless, the wide divergence in the rates found is impressive. It is even more striking in view of the fact that an important group of the chronically ill—persons in long-term medical care institutions—were not included in the present study. It is difficult to state concisely and specifically what conditions are included in these data on "chronic diseases." In the final analysis, the definition is the list of forty-seven diagnostic categories, plus two "all other" groups, for which data are presented in Appendix F. When the clinical examinations were performed, the physicians were asked to record all conditions, acute or chronic, except dental caries, refractive errors, upper respiratory infections, and pregnancy without complications. Because a person would be unlikely to make the effort to 1 Collins, Selwyn D., Phillips, F. Ruth, and Oliver, Dorothy S. "Specific Causes of Illness Found in Monthly Canvasses of Families: Sample of the Eastern Health District of Baltimore, 1938-43." Public Health Reports 65:1235-1264, September 29, 1950. 3 Some of these differences are discussed in Chapter 4.

49

50

VOLUME A N D CHARACTER OF CHRONIC DISEASE

attend the clinic while suffering from an acute condition, very few such conditions were diagnosed, and were subsequently deleted, when they could be identified, in the editing procedure. Also deleted were conditions which, though chronic in nature, were of small significance for present or future health such as moles, cysts, scars, and other defects not affecting functional capacity. An additional group of conditions including kyphosis, flat feet, and deflected nasal septum were retained only if they were described as "severe" or "marked." Definitions of pathologic abnormalities which were recorded as diagnoses—to the extent to which they could be established—are given in Appendix B. Table 4 shows for the Baltimore survey, the number and prevalence rates for all chronic diseases, by age, sex, color, and annual family income. In addition to conditions which were known to the patient or his family, these data include cases that were not causing any symptoms and cases that had not been diagnosed previously. Many of the patients evaluated had several conditions; no attempt has been made to classify TABLE 4.

Prevalence of all chronic diseases, by age, by sex, by color, and by annual family income (unadjusted and age-adjusted) 1 Rate per 1,000 persons (based on weighted number of diseases)

Age, sex, color, and income

Number of diseases ( unweighted)

All chronic diseases

1,892

1,566.5

1,566.5

Age Under 15 15-34 35-64 65 and over

98 252 1,067 475

406.9 1,204.6 2,199.1 4,041.8

XX

Sex Male Female

784 1,108

1,392.9 1,722.6

1,448.6 1,670.9

Color White Nonwhite

1,388 504

1,635.1 1,386.5

1,553.3 1,608.3

475 533 412 214

1,985.6 1,501.9 1,460.3 1,462.7

1,806.9 1,592.0 1,518.7 1,418.8

Annual family income2 Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over

Unadjusted

Age-adjusted

XX XX XX

1 Unadjusted figures are actual figures. Age-adjustment produced figures as they would be if there were no age differences between the white and nonwhite groups, between the sex groups, and among the various income groups. All age-adjusted data in this report were computed by the indirect method of applying age-specific rates to the number of persons (weighted) in each age-sex, age-color, and age-income group. 2 Excludes cases with annual family income unknown (one tenth of all persons).

PREVALENCE OF ALL CHRONIC DISEASES TABLE 5. Age AU ages Under 15 15-34 35-64 65 and over

51

Prevalence of all chronic diseases, by age and sex

Number of diseases funweighted)

Rate per 1,000 persons (based on weighted number of diseases)

Both sexes

Male

Female

Both sexes

Male

Female

1,892 98 252 1,067 475

784 64 96 449 175

1,108 34 156 618 300

1,566.5 406.9 1,204.6 2,199.1 4,041.8

1,392.9 522.2 1,038.5 1,883.8 4,271.7

1,722.6 284.7 1,338.6 2,493.4 3,906.0

each patient by his "primary" condition; therefore, the data on prevalence in this chapter relate to number of conditions rather than patients. Prevalence by Age It is well known that chronic disease is more prevalent among old people than among young people. Quantitative information on the nature of the relationship 3 between chronic disease and age, especially for particular chronic diseases, has been scant. Data from the Baltimore study are informative on this relationship. As shown in Table 5, children under age 15 had 407 diseases per 1,000 population (4 diseases among 10 children), while persons aged 65 and over had 4,042 chronic diseases per 1,000 persons, an average of 4 diseases each, and 10 times the rate among children. People aged 15 to 34 had 1,205 diseases per 1,000, and those 35 to 64 had 2,199 per 1,000. This relationship is presented graphically in Figure 1. Prevalence by Sex Chronic diseases were more prevalent among women than among men (Table 5 ) . For all chronic diseases combined, the rate was 1,723 per 1,000 women, as compared with 1,393 per 1,000 men. Part of the difference in prevalence is due to the fact that the women were somewhat older than the men—for example, 8 per cent of women but only 6 per cent of men in the sample were aged 65 or older. When the difference in age distributions of males and females has been taken into account, the prevalence of chronic disease remains higher for females (1,671 per 1,000) than for males (1,449 per 1,000), but the difference between the sexes is substantially reduced. 8 For some purposes, differences in the age distributions of the two sex groups, the two color groups, and the four income groups make it important to observe the prevalence of chronic disease and disability among these groups with differences in age distribution taken into account. In this report some of the data are presented as both unadjusted and age-adjusted rates; others are presented as age-specific rates. For those not so presented, age-adjusted or age-specific rates may be computed from data presented in Appendices E and F.

52

VOLUME A N D CHARACTER OF CHRONIC DISEASE

FIGURE 1. Prevalence of all chronic diseases per 1,000 persons, by age and sex

Age

The prevalence of chronic diseases was considerably higher for females between the ages of 15 and 64 than for males in this age range. Under age 15, however, the rate for boys was nearly twice the rate for girls, and the rate for aged men was slightly above that for aged women (Table 5 and Figure 1). Prevalence by Color Counter to expectation, chronic diseases were found to be more prevalent among whites (1,635 per 1,000) than among nonwhites (1,387 per 1,000) in Baltimore (Table 4 ) . The white population was a substantially older group than the nonwhite, however, with median ages of 32.7 and 28.4 years, respectively, and thus, when the prevalence rates for all chronic diseases are adjusted for differences in the age distribution of the two groups, the rate for whites is a little lower (1,553 per 1,000) than for nonwhites (1,608 per 1,000). Age-specific prevalence rates for each group are given in Table 6. There were shifts in the prevalence rates by color—and age, too—for which no explanation is available. The rate for nonwhites exceeded the rate for whites by about one fourth at ages

PREVALENCE OF ALL CHRONIC DISEASES TABLE 6.

Prevalence of all chronic diseases, by age and color

Number of diseases

All ages Under 15 15-34 35-64 65 and over

53

(unweighted)

Rate per 1,000 persons (based on weighted number of diseases)

White and nonwhite

White

Nonwhite

White and nonwhite

White

Nonwhite

1,892 98 252 1,067 475

1,388 65 166 758 399

504 33 86 309 76

1,566.6 406.9 1,204.6 2,199.1 4,041.8

1,635.1 373.8 1,295.0 2,109.0 4,119.9

1,386.5 472.4 994.3 2,471.7 3,316.9

under 15 and by one sixth at ages 35 to 64. In the two other age groups the rate for whites exceeded the rate for nonwhites by about one fourth. Prevalence

by Income

Groups

Persons in families with annual incomes under $2,000 were found to have more chronic diseases (1,986 per 1,000 persons) than those in families with larger incomes. The lower prevalence rates were almost identical for each of the three other income groups—1,500 per 1,000 persons. There was a heavy concentration of aged persons in the lowest income group—19 per cent being 65 or older as compared with 4 to 6 per cent in the higher income groups. When this age differential is taken into account, the prevalence is substantially lowered for the lowest income group and lowered slightly for the highest group. Rates for the two middle income groups are raised. Thus the over-all effect of adjusting for age differences is to reduce the range of variation in prevalence according to income, and to reveal a more nearly directly and constantly decreasing prevalence with increasing income. This relationship is shown in Table 7 and Figure 2. It is often claimed that chronic disease lowers people's incomes, or TABLE 7.

Prevalence of all chronic diseases, by annual family income (unadjusted and age-adjusted) Income

All incomes1 Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over 1

Number of diseases (unweighted)

1,892 475 533 412 214

Includes cases for whom income was unknown.

Rate per 1,000 persons (based on weighted number of diseases) Unadjusted

1,566.5 1,985.6 1,501.9 1,460.3 1,462.7

Age-adjusted

1,566.5 1,806.9 1,592.0 1,518.7 1,418.8

VOLUME A N D CHARACTER OF CHRONIC DISEASE

54 FIGURE 2.

Prevalence of all chronic diseases per 1,000 persons, by annual family income

2,400

2,000

o o o

Age-adjusted

1,600



Unadjusted

1,200

•σ ΗΟ

800

400

Under

$2,000-

$4,000-

$ 6 , 0 0 0 and

$2,000

$3,999

$5,999

over

Annual family income

that people with low incomes are more subject to attack by chronic diseases than people with higher incomes. While demonstrating that chronic diseases are widely prevalent among all income groups, these data support the existence of a relationship, though they do not indicate whether the low income or the disease is the causative factor in this relationship. Data presented in Chapter 13, however, strongly suggest that disabling chronic disease is more importantly a cause than an effect of low income level. DISTRIBUTION OF CHRONIC DISEASE

How were the 1,600 chronic conditions per 1,000 persons distributed? Were they concentrated in a small proportion of the noninstitutional population, or did almost everyone have a chronic condition? These data indicate that 65 per cent of the people had one or more

P R E V A L E N C E O F A L L C H R O N I C DISEASES TABLE 8.

55

Percentage of persons with one or more chronic conditions, and percentage with one or more substantial 1 chronic conditions, by age, by sex, and by color Percentage of persons (based on weighted number) with one or more

Age, sex, and color

Chronic conditions

Substantial chronic conditions

Total

64.9

44.4

Age Under 15 15-34 35-64 65 and over

29.2 63.5 85.8 95.4

17.4 31.0 65.9 85.2

Sex Male Female

61.5 68.0

41.0 47.5

Color White Nonwhite

66.7 60.3

43.8 46.1

1 A substantial condition is one which interferes with or limits the patient's activities or requires care, or is likely to do either of these in the future.

chronic conditions; and as would be expected, the conditions were not distributed evenly, particularly with regard to age. Less than 3 out of 10 (29 per cent) children under 15, but 19 out of 20 (95 per cent) aged persons had one or more chronic conditions. Perhaps more striking is the fact that nearly two thirds of young adults had a chronic condition. Table 8 shows the percentage of persons with chronic conditions, by age, sex, and color. SEVERITY OF CHRONIC DISEASE

Each condition diagnosed in clinical evaluation was classified according to its severity as "mild," "moderate," or "severe." For many diseases, including some of the more prevalent, it was feasible to establish definitions of the three classes.4 The relatively objective application of these definitions increased the degree of uniformity of classification by severity. For conditions for which definitions were not established, the examining physicians' judgment of severity was used. The nature and usual course of a particular disease chiefly determined the definition of classes of severity. The definitions varied from disease to disease, and it is not possible, therefore, to present a definition of the classes for all conditions combined. In the measurement of severity one or more of the following apply: increasing degree of disabling effects, 4

F o r definitions see pp. 393-399.

56

VOLUME AND CHARACTER OF CHRONIC DISEASE

more advanced stage of the disease, greater likelihood of fatality, need for more care, complications, or increasing pain. More than three fifths of the conditions (63 per cent) were classified as mild. One fourth (25 per cent) were moderate, and one eighth (12 per cent) were severe. The bulk of the conditions were near the lower end of the scale in terms of disability, need for care, and the other characteristics of severity noted above. Owing to the high prevalence of chronic conditions, a large proportion of which were mild in severity, the data have differing significance for different purposes. High prevalence is of interest to the study of epidemiology, to programs of prevention, and to the ranking of diseases by magnitude of prevalence—a procedure necessary to general planning. The relatively small proportions of chronic conditions which were severe or moderate give better perspective to the planning of programs of medical care and other services and facilities, as many mild conditions require little care or a different kind of care than the moderate or severe conditions. At the same time, of course, it cannot be assumed that all severe conditions require care. SUBSTANTIAL CHRONIC CONDITIONS

Of the 1,892 conditions discussed thus far in this chapter 1,183 were classified as "substantial." The designation "substantial" chronic conditions was arrived at when examining physicians were asked to differentiate between two types of conditions: those which interfered with or limited the patient's activities or were likely to do so in the future, or which required or were likely to require care; and those not causing disability and not requiring care. "Substantial" conditions might be either mild, moderate, or severe at their present stage of advancement. Under these criteria, 56 per cent of all chronic conditions diagnosed by the examining physicians were judged to be substantial. However, as Table 8 shows, less than half (44 per cent) of the people had a substantial chronic condition—despite the fact that nearly two thirds (65 per cent) had a chronic condition of some kind. The difference was greatest for young adults: the proportion with a substantial condition (31 per cent) being less than half the percentage of young adults having one or more chronic conditions. Of the 44 per cent of the people with one or more substantial chronic conditions, 19 per cent had only one such condition, and another 13 per cent had two; and the remaining 12 per cent had three or more. The relationship between substantial illness rates and "all illness" rates

PREVALENCE OF ALL CHRONIC DISEASES

57

varied a great deal with different diagnoses, as shown in Appendix F, Table F-36. Some conditions were designated as substantial in more than 80 per cent of the cases in which they were diagnosed. Among them were tuberculosis, malignant neoplasms, diabetes mellitus, psychoses, psychoneuroses, rheumatic fever, heart diseases, kidney diseases, sinusitis, and gallbladder diseases. On the other hand, some conditions were classified as substantial in less than 40 per cent of the cases in which they appeared. Included in this group were benign neoplasms of the uterus, hay fever, varicose veins, hemorrhoids, low back strain, and impaired hearing. While data on conditions other than substantial are needed in order to have as complete a count as possible of prevalence for the various diagnostic categories, it is the data on substantial conditions that are important in viewing the effect of chronic illness on people's lives. The substantial quality of a condition is probably more closely related to the existence of a need for care than is the severity. CHARACTERISTICS OF SUBSTANTIAL CHRONIC

CONDITIONS

Examining physicians were asked to record the following information about substantial conditions : Date of first symptom. Date of first correct diagnosis. Progress since first symptom or diagnosis. Whether the disease was recurrent. Whether the disease could have been prevented from reaching its present stage and, if so, the means of prevention. Whether there was an emotional factor in the patient's makeup which would adversely affect prognosis. The patient's attitude toward indicated care. Prognosis if care was received and prognosis if care was not received. This proved to be a large order. As many of these items of information were not requisite to the central purpose of the physician's examination —arriving at diagnosis—"unknown" was the only answer obtained in a number of instances. Data are presented on selected items for which the "unknowns" are not too large or which seem to have significance even in the presence of a large "unknown" element. The fact that a large number of physicians made the examinations, some examining comparatively small numbers of patients, made it more difficult to achieve consistent recording of this type of information than

58

VOLUME A N D CHARACTER OF CHRONIC DISEASE TABLE 9.

Year of first symptom of all substantial chronic conditions, by age

Year of first symptom Total 1954 1953 1952 1951 1950 1945-1949 1940-1944 1930-1939 Before 1930 Unknown

Percentage distribution (based on weighted number of conditions) All ages

Under 15

15-34

100 3 5 5 4 3 9 6 9 4 54

100 9 4 12 1 2 23 7

100

-

42

*

7 2 7 4 11 7 3 5 55

35-64 65 and over 100 3 3 5 5 2 8 4 9 4 57

100 2 6 4 3 5 5 8 16 4 48

* Less than 0.5 per cent.

would have been the case if only a few physicians had carried responsibility for all the examinations. Date

of First

Symptom

In this study, information about the year in which the first symptom appeared was obtained for only 46 per cent of the conditions diagnosed. It seems probable that a major reason for the date of first symptom's being recorded as unknown was the remoteness of the first occurrence. Frequent mention in the medical history that a patient has had a condition for many years, but with year of first symptom unknown, supports this belief. Most of the conditions for which the date of first symptom was known were of relatively long standing (Table 9). Even among children under 15, nearly one tenth of all conditions had exhibited their first symptoms 10 years ago or earlier. For the aged, the figure was one third. Past

Progress

Each condition was classified according to its progress since the first symptom or since the first correct diagnosis if there were no symptoms. More than one third (36 per cent) of the conditions were classified as having been progressive. The progression of one fourth (26 per cent) was unknown. Another third (32 per cent) were considered stationary, and only 6 per cent were classified as retrogressive (Table 10). The determination was based on the history of the specific condition in the individual and not on the basis of the general pattern of the disease involved. For example, even though diabetes is generally regarded as progressive, that classification was not assigned unless the history of the disease in the person being examined had been progressive. If the "net

P R E V A L E N C E O F A L L C H R O N I C DISEASES TABLE 10.

59

Progress, since first symptom, of all substantial chronic conditions, by age Percentage distribution (based on weighted number of conditions)

Progress

Total Progressive Stationary Retrogressive Unknown

All ages

Under 15

15-34

35-64

65 and over

100 36 32 6 26

100 14 60 10 16

100 26 30 8 37

100 37 29 6 29

100 52 31 4 12

trend" of a condition that had undergone ups and downs over a period of years could not be ascertained, the history of progress was considered "unknown." The percentage of conditions which were classified as progressive increased directly with age, from 14 per cent at ages under 15 to 52 per cent at ages 65 and over. Twice as many of the children's conditions (60 per cent) were considered stationary as were adults' conditions (about 30 per cent). Preventability

The possibility of primary prevention—the prevention of the occurrence of chronic disease—was not considered. However, an attempt was made to measure the amount of chronic disease which could have been prevented from progressing to the stage of causing illness, disability, and death, or could have been slowed in progress. Forty per cent of all substantial chronic conditions were considered to have been preventable in that their progression could have been retarded (Table 11). Nearly as many (37 per cent) could not have been prevented from reaching the stage at which they were at the time of clinical evaluation. For one fourth (23 per cent), preventability was unknown. These judgments were made in terms of the effectiveness of present-day knowledge and techniques, had these been available and utilized at the time when they could have been most effective. Starting at age 15 there was a steady decrease in preventability with advancing age. This decrease is undoubtedly due to the change in prevalence of certain diseases with increasing age. TABLE 11.

Preventability of all substantial chronic conditions, by age Percentage distribution (based on weighted number of conditions)

Preventability

Total Preventable Nonpreventable Unknown

All ages

Under J5

15-34

35-64

65 and over

100 40 37 23

100 43 44 13

100 56 20 24

100 40 37 23

100 27 51 22

60

VOLUME A N D CHARACTER OF CHRONIC DISEASE

Patient's Attitude

toward Care

The attitude of the patient toward the care indicated for his condition is important in the treatment of chronic disease and can be the deciding factor in the success of therapy. With the patient's attitude toward indicated care "unknown" for one fourth (24 per cent) of the conditions diagnosed, the examining physicians recorded the patient's attitude toward needed care as essentially favorable for 57 per cent of the conditions, "mixed"—meaning that the patient vacillated in his attitude to care needed—for 14 per cent, and essentially unfavorable for 5 per cent of the conditions (Table 12). A more comprehensive discussion of attitudes toward health care is presented in Chapter 11. Emotional Factors Affecting

Prognosis

For nearly two thirds of the conditions (63 per cent), the examining physicians judged that no emotional factor existed which might affect the prognosis, and for 9 per cent, no judgment was made (Table 13). The physicians recorded that in 14 per cent of the conditions the patient had emotional problems which might adversely affect prognosis seriously, and in another 14 per cent, might adversely affect prognosis to some extent. This judgment by the examining physician was made in most instances on the basis of a single interview with the patient. It is interesting to compare these opinions about the presence of an emotional component adversely affecting the prognosis of chronic diseases with the data on prevalence of mental disorders in Chapter 4. Only 11 per cent of the patients examined were judged to have a mental disorder. Prognosis without Care Of the 1,183 substantial conditions diagnosed in this study, more than four tenths (44 per cent) were thought to have a prognosis of slow progression if the recommended care was not received (Table 14). One fourth (28 per cent) were expected to remain stationary with no improvement. The "prognosis without receipt of recommended care" was unknown for one fourth (24 per cent) of the conditions and was favorable, i.e., some improvement anticipated, for very few conditions. The proportion of conditions which were expected to progress slowly if no care was received was larger for the aged than for young persons. More than four tenths of conditions (43 per cent) in children under 15 were expected to be stationary, while for older persons the proportion was about one fourth.

P R E V A L E N C E O F A L L C H R O N I C DISEASES

TABLE 12.

Patient's attitude toward care of all substantial chronic conditions, by age Percentage distribution (based on weighted number of conditions)

Attitude Total Essentially favorable Mixed Essentially unfavorable Unknown

TABLE 13.

All ages

Under 15

15-34

100

100

100

100

100

57 14

50 6

58 16

53 16

74 6

5 24

3 41

3 23

5 26

9 11

35-64 65 and over

Presence of an emotional component affecting prognosis of all substantial chronic conditions, by age Percentage distribution (based on weighted number of conditions)

Emotional component Total May seriously affect prognosis May affect prognosis to some extent No emotional component Unknown

TABLE 14.

61

All ages

Under 15

15-34

100

100

100

35-64 65 and over 100

100

14

4

22

15

8

14 63 9

16 77 3

11 58 9

20 56 9

5 78 9

Prognosis of all substantial chronic conditions without care, by age Percentage distribution (based on weighted number of conditions)

Prognosis Total Rapid progression Slow progression Stationary, no improvement Slight temporary improvement Marked temporary improvement Slight permanent improvement Marked permanent improvement Complete recovery Unknown * Less than 0.5 per cent.

All ages

Under 15

15-34

100 2 44 28

100 3 36 43

100 -

*

-

36 25 2

-

-

-

*

* *

24

3 -

15

-

• *

36

35-64 65 and over 100 3 45 27

100 2 54 29

*

*

-

-

1 *

25

* -

15

62

VOLUME A N D CHARACTER OF CHRONIC DISEASE TABLE 15.

Prognosis of all substantial chronic conditions with care, by age Percentage distribution (based on weighted number of conditions)

Prognosis Total Rapid progression Slow progression Stationary, no improvement Slight temporary improvement Marked temporary improvement Slight permanent improvement Marked permanent improvement Complete recovery Unknown

All ages

Under]5

15-34

100 1 14 14 5 4 4 18 10 31

100 3 2 35

100

-

5 3 16 24 12

-

3 4 2 4 5 15 20 49

35-64 65 and over 100 1 11 13 6 4 4 22 g 31

100 ψ 37 17 10 1 1 11 1 21

* Less than 0.5 per cent.

Prognosis with Care In contrast to the very small number of conditions with a prognosis of improvement if recommended care was not received, complete recovery was expected for one tenth if the indicated care was received, and marked permanent improvement was expected for almost two tenths (18 per cent). This is shown in Table 15. Fewer conditions would be slowly progressive with care than without (14 per cent compared with 44 per cent), and fewer would be stationary (14 per cent compared with 28 per cent). Reflecting the difficulty of estimating the effectiveness of treatment in particular cases of some chronic diseases, even though the general pattern of response to therapy of a condition is known, the proportion of conditions for which the prognosis with care was unknown (31 per cent) was larger than the proportion for which the prognosis without care was unknown (24 per cent). Receipt of needed care would increase the likelihood of complete recovery much more for children and young adults than for older persons. Conversely, the proportion of conditions which would continue to be slowly progressive even though care was received was smaller among young than among older people. DISABLING EFFECTS OF CHRONIC CONDITIONS

Chronic diseases have been shown to be highly prevalent, affecting 65 per cent of the noninstitutional population, and constituting an average of 1.6 conditions per person. But, in view of the very large number of chronic conditions found to be mild in terms of severity it is not surprising that relatively small numbers of persons were disabled by their

PREVALENCE OF ALL CHRONIC DISEASES

63

chronic diseases. Nevertheless, the number was so small as to be striking. Three kinds of measures of the disabling effect of chronic conditions were used in the evaluation of the sample of Baltimoreans: 1. Limitation on ability to perform 11 selected activities of daily living. 2. Limitation on over-all functional capacity. 3. Limitation on ability to work, keep house, or attend school, whichever was the person's usual activity. The data presented in this chapter represent the examining physician's judgment of the disabling effect of chronic disease and may or may not coincide with the patient's concept of his situation. Each concept—the physician's and the patient's—is useful for the purposes to which it is suited. Data on the patient's concept of the disabling effect of his chronic disease are particularly important because they reflect how, as a result of his concept of disability, he behaves in relation to his usual activities. Information on this point is presented in Chapter 13. Activities

of Daily

Living

Classification

Only 4 per cent of the population were limited in the performance of any of the following 11 activities of daily living selected for the measurement of disability: Ability to be out of bed Dressing self Moving about Caring for body hygiene Climbing stairs Performing toilet functions Travelling on public conveyances Continence Feeding self Speaking Writing The prevalence of limitation on activities of daily living was closely related to age; only a little more than 1 per cent of persons under age 35 had any limitation, while 30 per cent of those aged 65 or older had some limitation on one or more of the 11 activities (Table 16). These limitations were about 3 times as common among women (6 per cent) as among men (2 per cent). This is probably partially a reflection of the facts that ( 1 ) the women in the sample were on the average older than the men, and disability is more prevalent among the elderly, and (2) with age differences taken into account, chronic diseases were 15 per cent more prevalent among women than men. It seems unlikely, however, that these factors could entirely account for a difference of this size between the sexes in the prevalence of disability. It appears, therefore, that chronic diseases are truly more often disabling among women than among men.

64

VOLUME AND CHARACTER OF CHRONIC DISEASE

TABLE

16.

Persons with limitation on one or more activities of daily living, by age, by sex, by color, and by annual family income Unweighted number

Weighted number

Age, sex, color, and income

Total

With limitation

Total

All ages Under 15 15-34 35-64 65 and over

809 169 159 375 106

121 8 9 51 53

11,579.2 3,143.2 3,208.9 4,413.3 813.8

497.0 37.5 35.8 180.7 243.0

4.3 1.2 1.1 4.1 29.9

Both sexes Male Female

809 368 441

121 40 81

11,579.2 5,483.5 6,095.7

497.0 117.4 379.6

4.3 2.1 6.2

White and nonwhite White Nonwhite

809 572 237

121 85 36

11,579.2 8,384.8 3,194.4

497.0 416.4 80.6

4.3 5.0 2.5

All incomes Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over Unknown

809 158 239 190 131 91

121 36 24 25 13 23

11,579.2 1,496.5 3,685.2 2,840.4 2,242.4 1,314.7

497.0 123.2 102.1 72.4 159.5 39.8

4.3 8.2 2.8 2.5 7.1 3.0

With limitation Number

Percentage of total

The proportion of white persons with some disability in the activities of daily living was twice the proportion for nonwhites. The great age differences between the two groups are responsible for much of this difference in prevalence of disability. Fewer persons in the middle income groups than in either the lowest or highest income group were disabled. More persons (about 3 per cent of the population) were limited in moving about, climbing stairs, and travelling on public conveyances than were limited in any other activity of daily living. A very large proportion of the persons with limitations on any one of these three activities were limited on all three (Table 17). The degree of the limitation on each of the activities of daily living was classified according to categories which were somewhat different for the various activities. These classifications can be grouped into 3 categories which are identical for 7 of the 11 activities used in the study: ( 1 ) can do without help, but with difficulty; (2) can do with help of either a person or a mechanical aid, or both; and (3) cannot do (Table 17). About two thirds of the persons who were limited in their ability to move about or climb stairs had only the relatively minor limitation of being able to do the activity without help but with difficulty. The other third either performed the activity with help or could not do it at all.

PREVALENCE OF ALL CHRONIC DISEASES TABLE 17.

65

Persons with limitation on seven selected activities of daily living Percentage of persons evaluated (based on weighted number)

Activity of daily living

Unweighted number

Weighted number

Moving about Climbing stairs Travelling on public conveyances Feeding self Dressing self Caring for body hygiene Performing toilet functions

104 94

332.3 374.8

2.9 3.2

2.1 2.3

0.4 0.3

0.3 0.6

99 12 41

336.7 19.8 108.8

2.9 0.2 0.9

0.8

1.7 0.2 0.7

0.5 0.2

44

112.8

1.0

*

0.8

0.2

28

47.8

0.4

*

0.4

Total

Can do without help, Can do with but with help1 difficulty

*

0.1

Cannot do

*

-

1

Help either of a mechanical aid or of another person, or both. * Less than 0.05 per cent.

Thus, for most of the persons with limitation on these activities, the limitation was largely a matter of personal inconvenience or discomfort, rather than a disability that required the help of other persons or services. For those persons who had a limitation on travelling on public conveyances, three fourths could travel only with help or could not travel at all. Smaller proportions (not more than 1 per cent) were limited in their ability to feed themselves, dress themselves, take care of body hygiene, and perform toilet functions. Nearly all of those with any limitation on these activities required help in performing them. Similarly small numbers of persons were limited in their ability to speak ( 1 per cent), and to write (0.3 per cent), and in bowel and bladder control (0.3 per cent), or were confined to bed beyond normal sleeping hours (0.5 per cent). For each person with a limitation on any activity, the examining physician estimated his potential for improvement, with the results shown in Table 18. For the 3 activities for which the largest numbers of persons had limitations, the percentages with potential for improvement were 8 for moving about, 5 for climbing stairs, and 18 for travelling on public conveyances. The proportions with potential for improvement were higher for some of the other activities—for which fewer persons had limitations. One third or more of the persons with limitation on speaking, dressing themselves, or feeding themselves were thought to have a potential for improvement.

66

VOLUME AND CHARACTER OF CHRONIC DISEASE

Even when it was estimated that there was a potential for reduction of the limitation on activities of daily living, the degree of improvement anticipated was relatively small. For three fifths of the activities, the potential was for improvement only to a next classification of lesser severity of limitation (see Appendix H, Exhibit IV, for these classes). If all the estimated potential was achieved, the number of persons with some remaining limitation would be reduced by only the following percentages : Ability to be out of bed 21.8 Moving about 4.1 Climbing stairs 3.0 Travelling on public conveyances 14.8 Feeding self Dressing self 4.1 Caring for body hygiene 1.5 Performing toilet functions 3.8 Continence 9.3 Speaking 17.4 Writing 3.2 In evaluating these rather discouraging data on the potential for improvement of persons disabled by chronic disease, certain possible explanations should be remembered: that either most potentials have already been achieved, or that the diseases causing disability are not subject to effective treatment leading to less disabling effects. Over-All

Functional

Classification

Measurement of disability in terms of specific activities of daily living is useful in describing disability and in analyzing the estimated potential for improvement. It is also useful to have a single measure describing an individual's disability. Such a measure was attempted in the "over-all functional classification" (Table 19). In these terms, 91 per cent of the population were without any limitation of activity owing to chronic disease. Most of the other 9 per cent had only slight or moderate limitation, with about 1 per cent in the more disabled group. It is, of course, the latter group which constitutes a major portion of the problem of care. Some of the persons, especially those with slight limitation of over-all functional ability, have no specific disability in regard to the activities of daily living discussed in the preceding section, but are limited in an overall sense by the infirmities of illness and age.

PREVALENCE OF ALL CHRONIC DISEASES

TABLE 18.

67

Limitation of activities of daily living of persons evaluated, and proportion with potential for improvement Persons with limitation Total number

Activity of daily living

Ability to be out of bed Moving about Climbing stairs Travelling on public conveyances Feeding self Dressing self Caring for body hygiene Performing toilet functions Continence Speaking Writing

TABLE 19.

Those with potential Weighted Unweighted NumPercentage number ber of total

Unweighted

Weighted

29 104 94

49.1 332.3 374.8

5 13 8

10.7 25.2 17.5

21.8 7.6 4.7

99 12 41 44 28 13 19 23

336.7 19.8 108.8 112.8 47.8 37.7 116.9 34.5

10 3 9 5 1 3 3 4

58.9 6.4 53.3 7.6 1.8 3.5 56.7 5.8

17.5 32.3 49.0 6.7 3.8 9.3 48.5 16.8

Over-all functional classification of persons evaluated Classification

All classes Without limitation of activity Slight limitation of activity, but able to carry on usual activities with modest precautions Moderate limitation of activity; condition substantially alters mode of life, but person is adequate to meet his own needs and requires no personal or nursing care Has substantial disability, is ambulatory without personal assistance, but needs limited help with one or more activities. Can be left alone most of the time, i.e., other members of household can be employed if necessary So disabled that personal care services must be available most of the time, yet able to take care of most of own personal needs. Some adult person must remain at home to be available when needed So disabled, either physically or emotionally or both, as to require primary attention of an attendant type throughout waking hours and on call at night Chair- or bed-ridden and requiring practical or professional nurse care 8 hours or more daily

Percentage (based on weighted number of persons) 100.0 90.6 5.8

2.6

0.5

0.1

0.4 0.1

68

Usual Activities

VOLUME A N D CHARACTER OF CHRONIC DISEASE

Classification

A third measure of the disabling effect of chronic disease and an estimate of potential for improvement was made in terms of the effect on the "usual" activities of working, keeping house, or attending school, whichever was most appropriate in the individual situation. The estimate excluded persons whose usual activities were no longer one of these three for reasons other than health. For example, an estimate was not made for an aged man who, though unable to work at the time of evaluation, had retired from work owing to age rather than poor health. An estimate was made, however, if the reason for retirement was clearly ill health. Children of school age who, owing to chronic disease, were limited in their ability to participate in schooling constituted 0.8 per cent of the persons of all ages. Most of these (0.6 per cent) were attending school, but their diseases limited the kinds of school activities participated in or reduced their efficiency as students. More frequently, women whose usual activity was keeping house were limited in their ability to carry on this activity. Excluding aged women who because of their family situations no longer needed to take major responsibility for care of a home, 1.9 per cent of the population were women who had some limitation on this score. Of this group with a limitation, almost all (1.8 per cent) were actually carrying out some or all of the duties of a housekeeper, but were limited either in the number of kinds of tasks they performed or in their efficiency in carrying out these tasks. Only 0.2 per cent of the population were housekeepers who were unable to do their job at all because of chronic disease. This might be interpreted as either evidence that chronic disease rarely disables housewives entirely, or as a commentary on their determination to carry on despite the adverse circumstances imposed by chronic disease. The proportion of persons in the population who had some disabling effects on their usual activity of working (3.7 per cent) was larger than the proportion disabled for keeping house or attending school. Of the 3.7 per cent of persons so limited, 1.5 per cent had no limitation if they were selectively placed; 1.3 per cent were entirely unemployable; and the remainder had intermediate degrees of disability.5 Only a small percentage (15.1) of the persons judged to be disabled for their usual activities, was considered to have a potential for improvement. The percentage was higher for housekeepers (21.7) and for ° Except when they were judged to have a disability for working, keeping house, or attending school, persons in the sample were not classified as to their usual activity. Therefore, it is impossible to present the disabled as an exact proportion of the "usual activity" group to which they belonged.

P R E V A L E N C E OF A L L C H R O N I C D I S E A S E S

69

workers (21.4) than for school children (1.0). For most of those estimated to have a potential for improvement, the achievement of this potential was expected to result in only partial alleviation of their disability. Those for whom complete removal of disabling effects was considered possible represented only the following percentages of all the disabled: Persons working 4.5 Persons keeping house 21.7 Persons going to school 1.2 The existence of a potential for improvement is of little significance unless there is a reasonable chance of achieving it. The likelihood of achieving the potential for improvement was estimated for persons having some limitation on ability to work. These estimates were used also in connection with the referral for vocational rehabilitation discussed in Chapter 7 and are summarized in the tabulation below. Only a relatively small number of persons limited in their ability to work had any potential for lessening that limitation. The attempt to lessen the handicap of this small number would probably be successful in only about half the cases, it was believed. The outcome was thought to be doubtful in another one fourth, and likely to be unsuccessful in almost a fourth.

Prognosis for achieving improvement potential Number of persons with potential for Likelihood of achievement of improvement

Total Probably successful Doubtful Probably unsuccessful Unknown

improvement

Weighted Unweighted number

Number

271 14 6 6 1

91.0 46.6 22.5 20.8 1.1

Percentage distribution 100.0 51.2 24.7 22.9 1.2

1 This figure is smaller than the number of cases referred for vocational rehabilitation in Chapter 7 for several reasons, the most important being that the estimates here are limited to persons whose disability affected their ability to work, which was their usual activity.

Obstacles to achievement of an estimated rehabilitation potential arise from several sources. The one most frequently evident was the attitude of the patient himself.6 For almost one tenth of the persons with limited ability to work (Table 20), no substantial obstacle was known; for more than half, the person's attitude was the major obstacle to improvement. • S e e Chapter 11.

70

V O L U M E A N D CHARACTER OF CHRONIC DISEASE

TABLE 20.

Major obstacles to rehabilitation of persons with limited ability to work Number oj persons with limitation Major obstacle

Total No substantial obstacle known Failure of medical restoration Progression of existing condition Advanced age Attitude of patient Attitude of family Attitude of physician Attitude of prospective employers

Unweighted number 27 5 1 1 13 1 4

Weighted Number 91.0 8.3

100.0 9.1

1.6

1.8

20.3 1.4 47.6 2.5 3.0 6.3

22.3 1.5 52.3 2.7 3.3 6.9

These findings with respect to disability for usual activity are essentially consistent with those on disability for activities of daily living, and with those presented in Chapter 7 on vocational rehabilitation potential. In general, it was found that the number of disabled persons in the noninstitutional general population of Baltimore at the time of this study was small; that of those disabled, only a few had a substantial potential for improvement; and that for those considered to have a potential, many obstacles stood in the way of success. This latter group comprises the "backlog" of noninstitutionalized disabled and probably includes a few of the constant stream of people becoming disabled and being rehabilitated, either through their own efforts or through the services of community agencies. PERSONS WITH NO CHRONIC CONDITIONS

It is perhaps as important to examine the characteristics of persons who are well as to consider those with chronic disease. As shown in Table 21, 35 per cent of all persons had no chronic disease as measured by this study. The most striking fact shown in this table is the relationship of age to good health. The proportion of persons with no conditions ranged from 71 per cent for those under age 15 to only 5 per cent for persons 65 and over. Under age 15, there were more females than males with no conditions; after age 35, the relationship was reversed and there were many more males than females with no conditions. There were no females over age 65 with no conditions. Fifty-six per cent of all persons had no substantial chronic conditions. This figure, for all ages combined, varied only slightly for the different color and sex groups except that slightly larger proportions of males than

PREVALENCE OF ALL CHRONIC DISEASES

71 1

TABLE 21.

Persons with no conditions on clinical evaluation, expressed as a percentage of the weighted number of persons evaluated, by age, sex, and color Both sexes

Age Total All ages Under 15 15-34 35-64 65 and over

White

35.1 70.8 36.5 14.2 4.6

33.3 74.5 30.1 15.7 5.1

Male Nonwhite 39.7 63.3 51.3 9.7 -

Total

White

38.5 63.8 36.9 24.1 12.5

38.5 72.8 26.9 27.6 13.5

Female Nonwhite

Total

NonWhite white

38.4 46.7 61.0 13.7

32.0 78.2 36.2 4.9

28.6 76.4 32.8 4.7

-

-

-

41.0 81.9 43.9 5.8 -

1

Figures for each age, sex, and color group are exact figures; most others are partially estimated.

females had no substantial chronic conditions (Table 22). As with the percentage of persons with no conditions there was striking variation with age. In each color and sex-group there was, as age increased, a sharp and uninterrupted decrease in the proportion with no substantial condition—with the single exception that the figure for white males aged 15 to 34 was larger than that for white males under 15. An interesting difference in rates by color is observed in the age breakdown. Under age 35, there were only minor differences in the rate of well persons. However, after age 35, there were many more white persons than nonwhites without substantial chronic disease. To the extent that these crude data constitute a measure of over-all health, it is worth noting that there was a difference in the timing of the worsening of health—or advent of substantial chronic illness—between males and females. There were more well females than males under age 15. However, during the succeeding 20 years, the percentage of well males increased a little while the percentage of well females dropped from 88 per cent to 58 per cent. The percentage of well males decreased substantially after age 35 and from then on became about the same as the rate for females. TABLE 22.

Persons with no substantial chronic conditions on clinical evaluation, expressed as a percentage of the weighted number of persons evaluated, by age, sex, and color Both sexes

Age All ages Under 15 15-34 35-64 65 and over

Male

Total

White white

55.6 82.6 69;0 34.1 14.8

56.2 83.6 70.2 38.4 15.8

53.9 80.6 66.3 20.8 5.8

Female

Total

White white

59.0 77.4 82.6 35.8 12.5

60.8 78.5 86.2 41.2 13.5

54.4 75.3 73.9 19.8 -

Total

White

52.5 88.1 58.1 32.4 16.2

52.1 88.8 57.1 35.9 17.2

white 53.4 86.5 60.5 21.7 8.2

CHAPTER 4 PREVALENCE OF SELECTED DISEASES, THEIR CHARACTERISTICS AND DISABLING EFFECTS

Effect of Sampling Variability Heart Disease and Hypertension Diabetes Mellitus Neoplasms Arthritis Mental Disorders Syphilis

75 76 87 90 92 95 100

Chapter

4 Prevalence of Selected Diseases, Their Characteristics and Disabling Effects For a few of the disease groups which were found most frequently in clinical evaluation—heart disease, hypertension without heart involvement, diabetes mellitus, neoplasms, arthritis, mental disorders, and syphilis— data are presented in the following pages. These diseases have been selected for discussion here because they are widely prevalent and are of major concern to medical and related programs. Data on 31 other disease groups are contained in Appendix F. The names of the various disease groups adequately indicate for most purposes the kinds of cases included in the groups. Definitions of the groups in terms of the International Statistical Classification of Diseases, Injuries, and Causes of Death (1948 revision) are given in Appendix F. EFFECT OF SAMPLING VARIABILITY

It is in order here to discuss generally the degree of reliance which can be placed on data based on relatively small numbers of cases. Most of the data in Chapter 3 concerning chronic diseases as a group are based on numbers sufficiently large to merit confidence that the statements made are valid for the population of Baltimore because there is a very small degree of sampling variability. In the following discussion of selected diseases or groups of diseases, the number of cases on which the discussion is based varies from 42 to 150. In the discussions of subdivisions of the groups of diseases the numbers are still smaller. In the classifications by age, sex, color, or income some of the rates are based on a very small number of cases. In these instances, the sampling variability may be so large that little reliance can be placed on the significance of the rate. Despite this, the presentation of data is frequently worthwhile since, when properly qualified, parts of the presentation may be useful. For example, 75

76

VOLUME AND CHARACTER OF CHRONIC DISEASE

it is pertinent to present in this report findings which show how syphilis was distributed among the various income groups, even though the number of cases in the higher income groups was not large enough to establish a reliable prevalence rate for these higher groups. As a matter of fact, the absence of cases in particular age, sex, or color groups can be as illuminating as the substantial rates presented for other groups. Three devices have been introduced to permit presentation of all the useful prevalence data collected and to safeguard against misuse or misinterpretation of rates which have large sampling variability. 1. Most tables show the number of cases (unweighted) on which the rates in that table are based. 2. All rates which are subject to a sampling variability exceeding 50 per cent are enclosed in parentheses.1 3. The standard error has been computed for the general prevalence rate for each disease discussed in this chapter (Table 23). Chances are two out of three that the sampling error will not exceed the standard error. 2 It was not feasible to compute the estimated sampling variability for all of the various prevalence rates by age, sex, color, and income which are presented as part of the discussion of a specific disease. A rough estimate of sampling variability for a subgroup, e.g., prevalence of all heart disease among males, may be made from data in Appendix F by a method suggested there. Sampling variability for a rate for subgroups of a diagnostic group is larger than sampling variability for the rate for the diagnostic group. HEART DISEASE AND

HYPERTENSION

Prevalence

The prevalence of heart disease of all types as determined by the study was 96 cases per 1,000 population and the rate for hypertension without heart involvement was 66 per 1,000. These rates for the noninstitutional population are much greater than most previously published rates. In the survey by the Committee on the Costs of Medical Care in 1928-1931, the annual case rate of heart disease, arteriosclerosis, and high blood pressure, combined, was found to be 13.5 per Ι,ΟΟΟ.3 The combined annual case rate for 6 surveys conducted between 1928 and 1943 was 1

Applies to text tables; not done for tables in Appendix F. Standard errors of prevalence rates for other diseases are presented in Appendix F, where the prevalence rates are also presented. 8 Collins, Selwyn D. "Causes of Illness in 9,000 Families, Based on Nationwide Periodic Canvasses, 1928-31." Public Health Reports 48:283-308, March 24, 1933. 2

PREVALENCE OF SELECTED DISEASES TABLE 23.

77

Estimated sampling errors

1

Estimated sampling error Diagnosis

Number per 1,000

Percentage of number per 1,000

All heart disease Coronary artery disease and angina pectoris Hypertensive heart disease Other heart disease

13.1

13.6

7.3 9.4 2

32.4 18.7 2

Hypertension without heart involvement

11.1

16.7

4.7

17.6

All neoplasms Malignant neoplasms Benign neoplasms of uterus Benign neoplasms of other sites

11.1 1.3 13.7 4.7

20.2 46.9 29.3 17.3

All arthritis Rheumatoid arthritis Osteoarthritis Other forms of arthritis

8.8 1.5 8.6 2.5 2 1.6 14.1

11.7 43.6 13.0 46.4 2 36.3 26.8

11.7 6.8

32.1 44.5

6.9

19.0

Diabetes mellitus

All mental disorders Psychoses Psychoneuroses Psychophysiologic autonomic and visceral disorders Other mental disorders Syphilis 1

The chances are two out of three that the percentage difference between the rate per 1,000 shown and the rate that would have been obtained from evaluation of the entire population of Baltimore would be less than the sampling error indicated. 2 Estimate not computed. Approximations derived from a freehand curve drawn through a scatter diagram plotted from data on numbers of unweighted cases and estimated errors for diagnoses for which they are computed are: Other heart disease—8 per 1,000 and 32 per cent All mental disorders—13 per 1,000 and 12 per cent

14.5 per 1,000 for heart disease.4 Furthermore, the Baltimore rates indicate the prevalence at a specific point in time in contrast with the other rates quoted which, as annual case rates, would be expected to be somewhat larger. The major factor accounting for the large difference in the rates is believed to be the method of collecting data. The earlier studies gathered data either solely or primarily by household interview surveys, while the Baltimore study data were derived from clinical tests and examinations. As noted in Chapter 14 of this report, only 25 per 1,000 persons 4 Collins, Selwyn D., Trantham, Katharine S., and Lehmann, Josephine L. Sickness Experience in Selected Areas of the United States. Public Health Monograph No. 25. PHS Publication No. 390. Washington, D.C., Government Printing Office, 1955.

78

V O L U M E A N D C H A R A C T E R OF C H R O N I C DISEASE

reported heart disease in the household interview of this study in contrast to the 96 per 1,000 diagnosed as having heart disease in the clinical evaluation. Another important factor which partially accounts for the differences in rates between this and other studies is that since heart disease is predominantly a disease of the aged, the population of 1953-1954 (with its higher proportion of old people) would be expected to have somewhat more heart disease than would the population of 15 to 30 years earlier. Since the term "heart disease" covers a group of different diseases affecting the same organ, it is important to examine the prevalence of the major component conditions. Table 24 shows the prevalence of heart disease and hypertension, by age, as found in the Baltimore study. Data concerning hypertension without heart involvement are also presented in the table but are distinguished from data on "all heart disease." A diagnosis of coronary artery disease was made for 23 per 1,000 people in the general population, of hypertensive heart disease for 50 per 1,000, and of other types of heart disease for 24 per 1,000. The 34 cases of "other heart disease" included 12 cases of rheumatic heart disease, 4 cases of congenital heart disease, and 18 cases in which the etiology of the heart condition was obscure. Excluded from the count of "heart disease" in Table 24 were functional heart murmurs and cardiovascular syphilis. Also excluded were 44 cases with abnormal electrocardiograms but without supporting clinical evidence of heart disease. In this group were cases with abnormal Τ waves, abnormal ST segments, right bundle branch blocks, and disturbances of rhythm. Several electrocardiograms were interpreted by a cardiologist as "consistent with myocardial infarction," with heart disease not diagnosed because of lack of other evidence. TABLE 24.

Diagnosis

All heart disease Coronary artery disease and angina pectoris Hypertensive heart disease Other heart disease Hypertension without heart involvement

Prevalence of heart disease and hypertension, by age Number of cases (unweighted)

Rate per 1,000 persons (based on weighted number of cases) All ages

Under 15

15-34

35-64

65 and over

150

96.4

(16.4)

(18.3)

122.0

574.7

41

22.5

21.4

204.0

75 34

50.2 23.7

(16.4)

(18.3)

82.9 (17.7)

264.8 (105.9)

77

66.4

-

(23.3)

131.2

141.6

PREVALENCE OF SELECTED DISEASES

79

The prevalence rates for heart disease derived from this study were so much higher than those previously published that it seemed desirable to have an independent review of the clinical records on which the diagnoses were based. Accordingly, two cardiologists, one from the National Heart Institute and the other from The Johns Hopkins Hospital 5 —neither of whom had had previous contact with the study—were asked to review the clinical records of the 150 cases diagnosed as heart disease by the study, the 14 cases in which heart disease had been suspected but not diagnosed, and 37 (one half) of the cases diagnosed as hypertension without heart involvement. The two cardiologists were in close agreement with each other and with the study findings on the total number with heart disease. There were differences of opinion on individual cases but these largely balanced out. The cardiologists agreed less closely with the study classifications by type, particularly in regard to arteriosclerotic heart disease. While 41 cases of arteriosclerotic heart disease were diagnosed in the study's clinical evaluation, the reviewing cardiologists diagnosed 73 and 68 cases, respectively. In subsequent discussion with the cardiologists, it became apparent that much of this difference was attributable to variations in interpretation of terms. The study had interpreted arteriosclerotic heart disease as including only cases of heart disease with a specific history of angina pectoris, a confirmed record of myocardial infarction, or classic EKG evidence of infarction. The reviewing cardiologists included in their arteriosclerotic heart disease classification older patients with unmistakable heart disease but with normal blood pressures and normal electrocardiograms, on the basis that autopsy findings in such cases usually confirm the diagnosis of arteriosclerotic heart disease. The procedure followed and the detailed results of the review by the two cardiologists are described in Appendix B. In short, the cardiologists' review indicated that the over-all prevalence rate for heart disease was at least as high if not higher than the rate of 96 per 1,000 reported by the study. The Hunterdon County study, using similar methods (clinical evaluation), produced similar but slightly higher rates. The combined evidence of these two studies indicates that the prevalence of heart disease has been grossly underestimated in the past. The prevalence rates presented in this chapter are based on the study 5 Luther L. Terry, M.D., Chief, General Medicine and Experimental Therapeutics Branch, National Heart Institute; and Richard S. Ross, M.D., Instructor in Medicine, The Johns Hopkins University School of Medicine.

80

V O L U M E A N D CHARACTER OF CHRONIC DISEASE

findings and have not been altered to conform to the classifications by the reviewing cardiologists. Severity In view of the high prevalence rates obtained, it is particularly important to examine the data in terms of severity and functional limitations. Heart disease was classified in terms of the New York Heart Association classification by functional capacity® as follows : Class I. Patients with cardiac disease, but without resulting limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea, or anginal pain. Class II. Patients with cardiac disease resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea, or anginal pain. Class III.

Patients with cardiac disease resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain. Class IV. Patients with cardiac disease resulting in inability to carry on any physical activity without discomfort. Symptoms of cardiac insufficiency, or of the anginal syndrome, may be present even at rest. If any physical activity is undertaken, discomfort is increased. Table 25 shows that over half (55 per cent) of all heart disease cases were in the group with no limitation of physical activity and an additional 30 per cent had only slight limitation of physical activity. Thus only 15 per cent had substantial physical limitations. Among the various types, the percentage with substantial limitation was highest (27 per cent) for coronary artery disease. Patients were also grouped according to the New York Heart Association therapeutic classification7 as follows : Class A. Patients with cardiac disease whose physical activity need not be restricted. Class B. Patients with cardiac disease whose ordinary physical activity need not be restricted, but who should be advised against unusually severe or competitive efforts. 6 New York Heart Association, Inc. Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Blood Vessels (5th edition), p. 81. N e w York, Peter F. Mallon, 1953. * Ibid., p. 82.

P R E V A L E N C E OF S E L E C T E D D I S E A S E S TABLE 25.

Distribution of heart disease, by functional capacity Percentage distribution (based on weighted number of cases)

Number of cases (unweighted)

Diagnosis

All heart disease Coronary artery disease and angina pectoris Hypertensive heart disease All other heart disease 1

81 1

ClaSS

Total

Cl SS

I

" II

C SS

C, SS

'" III

" IV

150

100.0

54.9

29.9

10.0

5.3

41 75 34

100.0 100.0 100.0

21.3 57.1 81.6

51.9 29.4 10.1

8.9 12.2 6.3

18.0 1.3 1.9

Excludes hypertension without heart involvement.

Class C.

Patients with cardiac disease whose ordinary physical activity should be moderately restricted, and whose more strenuous efforts should be discontinued. Class D. Patients with cardiac disease whose ordinary physical activity should be markedly restricted. Class E. Patients with cardiac disease who should be at complete rest, confined to bed or chair. Under this classification most of the heart disease diagnosed was so mild as not to require any restriction of activity or to require only the avoidance of unusually severe physical activity. Only a small group required a marked limitation in activity (Table 26). Problems of Differential Diagnosis The diagnosis of hypertension was based on clinical judgment of the examining physician without reference to formal rules. Consideration was given to a rule setting specific blood pressure levels, above which the diagnosis would be automatic. It was felt, however, that such a rule would lead to erroneous diagnoses particularly on persons with labile blood pressures. The diagnosis reflected evidence taken from previous TABLE 26.

Diagnosis

Distribution of heart disease, 1 by therapeutic classification Number of cases (unweighted)

All heart disease Coronary artery disease and angina pectoris Hypertensive heart disease All other heart disease 1

Percentage distribution (based on weighted number of cases) Class Tolal

Class

Class

A

Β

C

Class

Class

D

E

150

100.0

32.4

38.4

22.9

5.6

0.8

41 75 34

100.0 100.0 100.0

37.1 52.7

48.2 38.0 29.9

33.2 22.7 13.6

17.2 1.5 3.3

1.3 0.7 0.5

Excludes hypertension without heart involvement.

82

VOLUME AND CHARACTER OF CHRONIC DISEASE

medical records when they were available, history, appearance of the eyegrounds, and other physical findings, as well as blood pressure determinations. One of the most difficult clinical distinctions to make was between hypertension (without heart disease) and hypertensive heart disease. The latter is the direct result of the former, and it is frequently difficult to determine whether or not the heart has been affected by prolonged hypertension. In practice, the study classified as hypertensive heart disease only those cases with definite evidence of heart damage or enlargement. The prevalence of hypertensive heart disease (Table 24) was 50 cases per 1,000 persons and of hypertension without heart involvement, 66 per 1,000—a total of 116 per 1,000 having hypertension, with or without cardiac involvement. Patients with other types of heart disease and concomitant hypertension are not included in these figures. Prevalence by Age Heart disease was found to be about 30 times as prevalent among persons aged 65 and over as among persons under 35, and almost 5 times as prevalent as among persons aged 35 to 64 (Table 24). It is a striking observation that 575 per 1,000 persons aged 65 and over had heart disease. The several types of heart disease did not have identical relationships to age. No cases of coronary artery disease were found among persons under age 35, and the prevalence among persons aged 35 to 64 was 21 per 1,000. For persons aged 65 and over, it was about 10 times as great (204 per 1,000). Prevalence rates for hypertensive heart disease showed a similar pattern, but with less difference between the middle and old age groups. The rate was proportionately much higher than for coronary disease at ages 35 to 64 (83 per 1,000) but only a little higher at age 65 and over (265 per 1,000), as shown in Figure 3. The cases of heart disease among persons under age 35 included rheumatic heart disease and congenital malformations. There was no further increase in cases of hypertension without heart involvement beyond age 65. Long-standing hypertension tends to damage the heart and develop into hypertensive heart disease. Probably owing to this fact, the rates for hypertension without heart involvement were about the same for ages 35 to 64 and for ages 65 and older. When cases of hypertension and hypertensive heart disease are combined, the rate for ages 65 and older (406 per 1,000) is approximately twice the rate for ages 35 to 64 (214 per 1,000).

PREVALENCE OF SELECTED DISEASES

83

1

FIGURE 3. Prevalence of heart disease per 1,000 persons, by age

Age 1

Excludes hypertension without heart involvement.

Prevalence by Sex There was little difference between men and women in the prevalence rate of all heart disease combined, the rate for women being slightly higher. For particular types of heart disease, however, differences in prevalence rates were substantial. These are shown in Table 27. The rates for hypertensive heart disease were 39 per 1,000 for men and 61 per 1,000 for women—a difference which is not unexpected. For coronary artery disease the difference was reversed, the rates being 27 and 19 per 1,000, respectively, for men and women. Hypertension without heart involvement was more frequent among women (74 per 1,000) than among men (58 per 1,000). This is consistent with the rates for hypertensive heart disease. The difference in prevalence of hypertension TABLE 27.

Prevalence of heart disease and hypertension, by sex (unadjusted and age-adjusted)

Diagnosis

All heart disease Coronary artery disease and angina pectoris Hypertensive heart disease All other heart disease Hypertension without heart involvement

Number of cases [unweighted)

Rate per 1,000 persons (based on weighted number of cases) Unadjusted

Age-adfusted

Both sexes

Male

Female

Male

Female

150

96.4

93.6

99.0

102.0

92.1

41 75 34

22.5 50.2 23.7

26.8 38.6 28.1

(18.6) 60.6 19.7

30.8 41.3 29.7

(16.7) 57.0 18.6

77

66.4

57.8

74.2

59.0

72.7

84

VOLUME A N D CHARACTER OF CHRONIC DISEASE

among men and women (58 as against 74) was smaller than the difference for hypertensive heart disease (39 as against 61). When differences in the age distribution of men and women are taken into account, the prevalence rates of heart disease for the sexes remain about equal, but the rate for women is a little lower, rather than higher, than the rate for men. For coronary disease the excess of the rate for men (31 per 1,000) over the rate for women (17 per 1,000) is greater than in the unadjusted figures. However, for hypertensive heart disease and for hypertension without heart involvement, the differences between the rates for men and women are reduced a little. Prevalence

by

Color

Heart disease was substantially more prevalent among whites (104 per 1,000) than among nonwhites (78 per 1,000). The difference was great for coronary artery disease (Table 28) and was also observed for other types of heart disease than hypertensive heart disease. However, the latter, which accounted for about half of all heart disease, occurred about half again as often among nonwhites (69 per 1,000) as among whites (43 per 1,000). Hypertension without heart involvement was about one third more prevalent among nonwhites (83 per 1,000) than among whites (60 per 1,000), a relationship similar to that seen for hypertensive heart disease. The higher prevalence among whites than nonwhites is largely attributable to the facts that whites were an older group than nonwhites and that heart disease is a condition of advancing age. The age-adjusted rates of Table 28 show nonwhites to have had considerably more, rather than less, heart disease than whites. Even with age adjustment, however, corTABLE 28.

Prevalence of heart disease and hypertension, by color (unadjusted and age-adjusted) Rate per 1,000 persons (based on weighted number of cases)

Diagnosis

All heart disease Coronary artery disease and angina pectoris Hypertensive heart disease All other heart disease Hypertension without heart involvement

cases (unweighted)

Total

150

Unadjusted

Age-adjusted

n,, • Wh e "

Nonwhite

«... White

Non,.., white

96.4

103.5

77.8

92.1

112.0

41 75 34

22.5 50.2 23.7

30.4 43.2 29.9

(1.8) 68.5 (7.5)

25.8 38.4 28.0

(3.3) 98.0 (9.4)

77

66.4

60.2

82.7

56.6

98.4

P R E V A L E N C E OF S E L E C T E D D I S E A S E S

85

onary artery disease remained much more prevalent among whites than nonwhites. The excess of hypertension and hypertensive heart disease in nonwhites over whites is further accentuated by adjustment of the rates for differences in age distribution of the two groups. Prevalence by Income

Group

Heart disease was more prevalent among persons with annual family income under $2,000 than in the middle income groups, but tended to rise again for income group $6,000 and over. As shown in Table 29 and Figure 4, the differences in rates were reduced somewhat by age adjustments but the general trend remained very much the same. Table 29 also shows the relationship of specific cardiac diagnoses to income. It is worth noting that hypertension was found to be less prevalent in the lowest income group while hypertensive heart disease was more prevalent in this group. Characteristics of Heart Disease Dates of first symptom and diagnosis. For half of the cases, the date of first symptom of heart disease was unascertained or the disease had never caused symptoms, the latter accounting for 28 per cent. The first symptom occurred during the past five years for 17 per cent, between five and ten years ago for 13 per cent, and more than ten years ago for 20 per cent. More than one third (34 per cent) of persons aged 65 and over had had their first symptom ten years ago or earlier.

TABLE 29.

Prevalence of heart disease and hypertension, by annual family income

Diagnosis

All heart disease (unadjusted) Coronary artery disease and angina pectoris Hypertensive heart disease All other heart disease Hypertension without heart involvement All heart disease (age-adjusted) 1

Number of cases ( unweighted)

Rate per 1,000 persons (based on weighted number of cases) AU incomes1

Under $2,000

$2,000- $4,000- $6,000 $3,999 $5,999 and over

150

96.4

166.5

92.8

66.0

97.2

41 75 34

22.5 50.2 23.7

(45.0) 80.0 (41.5)

(20.3) 50.3 (22.2)

(21.7) 26.0 (18.3)

(21.1) (56.1) (20.0)

77

66.4

34.2

58.4

57.9

69.7

150

96.4

119.9

97.4

76.6

100.1

Includes cases for whom income was unknown.

86

VOLUME A N D CHARACTER OF CHRONIC DISEASE

FIGURE 4. Prevalence of heart disease1 per 1,000 persons, by annual family income 200

ut co cfl

α 100 to α) « η ο

Age-ad j ι

"ο s

50

Ε Under

$2,000-

$4,000-

$6,000 and

$2,000

$3,999

$5,999

over

Annual family income 1

Excludes hypertension without heart involvement.

Past progress. Heart disease is typically progressive, including cases with temporary remissions but with over-all progression. This classification was assigned to 55 per cent of the cases and one fourth were considered stationary. One fifth could not be classified. Preventability. The fact that much remains to be learned about the control of cardiovascular disease was borne out by the findings of this study. In 8 out of 10 cases (79 per cent) it was the examining physician's opinion that the disease could not have been prevented from progressing to its present stage, given present-day knowledge and techniques. Seven per cent were judged to have been preventable in this sense, and for 14 per cent no opinions were expressed. The proportion of nonpreventable cases was higher among the aged (86 per cent) than among persons aged 35 to 64. This probably reflects differences with age in the prevalence of various types of heart disease. Patient's attitude toward care. In two thirds of the cases for which any care was indicated, the examining physician recorded the patient's attitude toward care as essentially favorable. It was essentially unfavorable in 9 per cent of the cases, mixed in 12 per cent, and unknown in 11 per cent. Emotional factors affecting prognosis. Assuming that the care needed would be received and the physician's instructions followed, it was judged

PREVALENCE OF SELECTED DISEASES TABLE 30.

87

Prognosis of cases of heart disease, with and without recommended care Percentage distribution (based on weighted number of cases) Prognosis

Total Rapidly progressive Slowly progressive Stationary, no improvement Slight temporary improvement Marked temporary improvement Slight permanent improvement Marked permanent improvement Unknown

Without care

With recommended care

100 10 76 2 12

100 1 56 8 10 2 1 1 22

that in 9 per cent of the cases the patient's emotional make-up might seriously affect prognosis adversely, and that in another 18 per cent it might do so to some extent. It was thought that the course of organic heart disease might be adversely affected by emotional factors in approximately one fourth of the cases. The proportion was higher for persons aged 35 to 64 (42 per cent) than for aged persons (15 per cent), with most of the difference being in cases in which the effect might be moderate rather than serious. Prognosis and care. While it is difficult to predict particular developments in particular cases of most diseases, including heart disease, the probable effect of a given regimen can be estimated. If no care was given, three fourths of the cases were estimated to be slowly progressive and another one tenth rapidly progressive. Improvement was expected in none, and only 2 per cent were expected to be stationary (Table 30). If the recommended care was given, some improvement was estimated for 14 per cent, and 8 per cent were expected to be stationary. The proportion expected to be slowly progressive (56 per cent) or rapidly progressive (1 per cent) was much lower than if no care was given, but part of the reduction was due to the examining physicians' reluctance to estimate the effect of care in slowing or halting progress of the disease. DIABETES MELLITUS

Prevalence A total of 73 cases of diabetes mellitus were diagnosed, producing a prevalence rate of 27 per 1,000 of the noninstitutional population. This rate is probably an understatement of the total prevalence of diagnosable

88

VOLUME A N D CHARACTER OF CHRONIC DISEASE

diabetes since some patients in whom diabetes was suspected declined to undergo the glucose tolerance test which was needed for diagnosis. The diagnosis of diabetes was based on clinical judgment taking into consideration history, physical findings, blood sugar and urine sugar determinations. A two-hour glucose tolerance test was performed on patients in whom the diagnosis was in doubt. Glycosuria was not regarded as essential to the diagnosis but was present in most cases. Table 31 shows the prevalence of diabetes by age, sex, color, and annual family income. Prevalence by age and sex. Diabetes was found to be a little more prevalent at ages 35 to 64 (59 per 1,000 population) than in older persons, for whom the rate was 45 per 1,000. No cases of diabetes were found among children under 15; juvenile diabetes, while usually a severe disease, is relatively rare. There was very little diabetes among persons aged 15 to 34 (4 cases per 1,000 population)—only one fifteenth the amount found among persons in the 35 to 64 age group. There was no significant difference in the prevalence of diabetes between men and women. Prevalence by color. Whites were found to have diabetes less frequently than nonwhites, and adjusting for age increased this difference. The higher prevalence among nonwhites was observed in each age group (see Appendix F, Table F - 2 4 ) . TABLE 31.

Prevalence of diabetes, by age, by sex, by color, and by annual family income (unadjusted and age-adjusted) Age, sex, color, and income

Number of cases ( unweighted)

Total Age Under 15 15-34 35-64 65 and over

1

73 -

Rate per 1,000 persons (based on weighted number of cases) Unadjusted

Age-adjusted

26.7

26.7

-

XX

8 49 16

4.1 58.7 45.1

XX

Sex Male Female

32 41

24.3 28.9

24.5 28.6

Color White Nonwhite

55 18

24.6 32.3

23.1 38.4

Annual family income1 Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over

13 19 17 9

19.6 15.1 22.6 40.4

20.4 17.5 22.4 35.1

Excludes cases for whom income was unknown.

XX XX

P R E V A L E N C E OF S E L E C T E D D I S E A S E S

89

Prevalence by income group. There may be a substantial difference in prevalence of diabetes among income groups; the rate observed among persons with family incomes of $6,000 and over (40 per 1,000) was about twice the rate for the three lower income groups. Differences in age distribution among the income groups apparently have little relationship to the prevalence of diabetes; the main effect of adjusting for age is a slight lowering of the rate for persons in the highest income group. The apparent association of diabetes with high income is interesting and might conceivably be related to differences in diet. The number of cases on which the observation was based is small, however, and no conclusions can be drawn. Duration How long ago was the diagnosis of diabetes made on these patients? Table 32 shows a percentage distribution of the cases by year of diagnosis. Except for 2 cases (unweighted) which had been diagnosed a few months prior to evaluation, all cases shown as diagnosed in 1954 were diagnosed for the first time in the evaluation clinic. The fact that this group is so large—58 of the 59 per cent (of the weighted number of cases) which were first diagnosed in 1954 and 1955—supports the statement frequently made that there is at least one undiagnosed case of diabetes for each known case. Of the previously known cases, the median time since diagnosis was about 10 years. Secondary

Prevention

Medical science cannot today prevent diabetes mellitus, but it can do some things to limit or prevent complications which sometimes occur in the course of the disease. It was the opinion of the examining physicians TABLE 32. Year of diagnosis Total 1954 and 1955 1953 1952 1951 1950 1945-1949 1940-1944 1930-1939 Before 1930 Unknown

Year of diagnosis of diabetes Years since diagnosis XX

0 1 2 3 4 5-9 10-14 15-24 25 and over Unknown

Percentage distribution (based on weighted number of cases) 100 59 1 5 2 2 9 11 7 2 3

90

VOLUME AND CHARACTER OF CHRONIC DISEASE

that for 20 per cent of the diabetic patients progression of the disease to its present stage, often including complications, could have been prevented if present-day knowledge and techniques had been applied at the right time. Severity For lack of a better standard, severity of diabetes was estimated on the basis of insulin requirements for control of the disease. As shown in Table 33, the bulk of the cases were "mild," being controllable by diet alone. Patient's Attitude toward Care Successful management of diabetes frequently depends upon the full cooperation of the patient. The examining physicians classified the attitudes of patients toward the medical care that was estimated to be needed. For diabetic patients, this would involve attitudes toward insulin therapy, diet, foot care, and treatment of complications if present. Table 34 gives the result of this classification. The cases shown as having a mixed attitude toward care were persons who were cooperative in some phases of care but not in others, e.g., persons who took insulin regularly but did not follow prescribed diet or did not test urine as recommended. Seven per cent of the cases had unfavorable attitudes toward care and 24 per cent could not be classified because the information was insufficient. The latter group includes some patients who did not return to the clinic after test results revealing diabetes were available, so that their attitudes toward care of the newly diagnosed disease were not ascertained. NEOPLASMS

Prevalence In discussing the prevalence of neoplasms, it must be recognized that the term indicates a group of loosely related conditions rather than a single disease. The rates presented are based on 64 cases in which neoplasms were present at the time of evaluation. Cases which had been operated on for removal of neoplasms and in which there was no evidence of metastasis or recurrence were excluded from the count. Among the 809 evaluees, malignant neoplasms were diagnosed for 12 persons; 19 had fibroid tumors of the uterus; and 31 had benign neoplasms of other types. Because of the small number of cases, rates derived from these data must be used with caution. Table 35 shows the prevalence of neoplasms by age, sex, color, and annual family income.

PREVALENCE OF SELECTED DISEASES TABLE 33.

91

Classification of severity of diabetes, by insulin requirement

_ ,. Insulin requirement

Percentage distribution (based on . ,, , , , . weighted number of cases)

Mild: Controllable by diet, no insulin required Moderate: Controllable by diet plus less than 40 units of insulin Severe: Controllable by diet plus more than 40 units of insulin TABLE 34.

60.3 25.6 14.1

Patient's attitude toward care of substantial cases of diabetes1 Percentage distribution (based on weighted number of cases)

Number of cases Patient's attitude

Unweighted 69 38 11 12 8

Total Essentially favorable Mixed Essentially unfavorable Unknown

Weighted 289.3 154.2 45.5 21.6 68.0

100 53 16 7 24

1 A few cases of mild diabetes in aged patients with other severely disabling diseases were not regarded as substantial.

TABLE 35.

Prevalence of neoplasms, by age, by sex, by color, and by annual family income Age, sex, color, and income

All neoplasms1

Number of cases (unweighted)

64

Malignant neoplasms

12

Benign neoplasms of uterus2

Benign neoplasms of other sites

19

31

Rate per 1,060 persons (based on weighted number of cases) All neoplasms Age Under 15 15-34 35-64 65 and over Sex Male Female Color White Nonwhite Annual family income8 Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over 1

54.9

2.7

46.7

27.3

(5.4) 49.6 91.1 (70.3)

(5.4) (0.8) (1-5) (6.6)

(60.0) 73.1 (21.7)

15.1 51.5 (50.0)

28.0 79.1

(4.5) (1.2)

46.7

32.2 31.0

53.4 58.7

(3.4) (1.1)

38.2 69.4

29.7 21.1

(9.6) 75.5 37.7 (51.1)

(1.6) (5.7) (1.5) (0.4)

(11.7) (59.7) (21.8) (50.7)

40.0 25.9 (24.2)

Includes 2 cases (unweighted) of neoplasms of unspecified type. Rates are based on female population; the sum of rates for the types of neoplasms does not equal the rate for all neoplasms. • Excludes cases for whom income was unknown. 2

92

VOLUME AND CHARACTER OF CHRONIC DISEASE

Prevalence by age and sex. It will be noted that the prevalence of neoplasms was somewhat higher for the age group 35 to 64 than for either younger or older groups and that this was particularly true for benign neoplasms of the uterus. Benign neoplasms of sites other than the uterus were about equally prevalent among men and women. Prevalence by color. While there was little difference among whites and nonwhites in the prevalence of all neoplasms combined, the rate for benign neoplasms of the uterus (fibroids) was markedly higher for nonwhites (69 per 1,000) than for whites (38 per 1,000). Malignant Neoplasms There were only 12 cases of malignant neoplasms, or a rate of 3 per 1,000. This probably represents an underestimate, since the clinical evaluation was not exhaustive for cancer detection—for example, the Papanicolaou test for cancer of the cervix was not carried out. No previously unknown cases of cancer were discovered. In considering the neoplasm rates found it is especially pertinent to bear in mind that patients in nursing homes and chronic disease hospitals were not included in the sample. All the cases of cancer were among the population living at home. Types, sites, and duration. The variety of types and locations of cancers is of some interest. There were 2 cases of cancer of the stomach (ages 54 and 64), 2 cases of cancer of the rectum (ages 60 and 86), and 1 case of general abdominal carcinomatosis (age 84). There was 1 cancer of the breast (age 75) and 1 of the uterus (age 59). There was 1 cancer of the thyroid (age 25) and 1 osteosarcoma of the tibia (age 46). All these 9 cases had metastases. In addition, there were 1 case (age 19) of Hodgkin's Disease and 1 case (age 3) of lymphocytic leukemia. There was 1 case of rodent ulcer of the mouth (age 83). Of the 12 cases, this last was the only one with a favorable prognosis. This patient received early surgical treatment and had one small recurrence which was fulgurated. None of the cases of cancer had been diagnosed more than 5 years prior to clinical evaluation, and 80 per cent had been diagnosed within 2 years. ARTHRITIS

Prevalence Arthritis is usually considered to be the most widely prevalent of the chronic diseases. However, the clinical evaluation data of this study

PREVALENCE OF SELECTED DISEASES

93

revealed a prevalence rate of 75 per 1,000 persons for arthritis, and higher rates of prevalence for heart disease (96 per 1,000, excluding hypertension without heart involvement) and of mental disorders (109 per 1,000). Arthritis tends to be a painful condition and for that reason a higher proportion of cases would be known to the persons affected and to their physicians than would be true of other chronic conditions which produce fewer symptoms and bother the patient less. Most prevalence data published in the past have been based almost exclusively on the results of interviews with individuals or families, and it seems likely that the more symptomatic or disagreeable conditions would thus be reported more completely than others. At least one household interview survey8 yielded a rate of reported arthritis and rheumatism (both medically attended and not medically attended) equal to that found in clinical examination in this study. For most other chronic conditions, rates resulting from interview surveys were considerably below those resulting from diagnostic studies. Osteoarthritis, which causes nearly nine tenths of all cases of arthritis, is a difficult disease to define and to study. It is usually a gradual disease process that accompanies aging. It has been asserted that some x-ray evidence of osteoarthritis can be found in nearly every person 50 years of age or older. Thus, if the clinical evaluation procedure had included routine x-ray of designated joints, the resulting prevalence rate might have been considerably higher, though perhaps only a little additional disease of current significance would have been discovered. Table 36 shows the prevalence as found in the study of osteoarthritis, rheumatoid arthritis, and other forms of arthritis, by age, sex, color, and annual family income. Cases of myositis and fibrositis were rare and are not included in these data. Prevalence by age. Osteoarthritis, classically a disease of advancing age involving degeneration of the cartilage and bone of the joints, was found in no persons under age 35. The prevalence among persons aged 65 and over (487 per 1,000) was almost 6 times as great as the 84 per 1,000 among persons aged 36 to 64. Prevalence by sex. Osteoarthritis was more than twice as prevalent among women (93 per 1,000) as among men (37 per 1,000). Although the female population was somewhat older than the male population, ad8 Woolsey, Theodore D. "Prevalence of Arthritis and Rheumatism in the United States." Public Health Reports 67:505-512, June 1952.

VOLUME AND CHARACTER OF CHRONIC DISEASE

94 TABLE 3 6 .

Prevalence of arthritis, by age, by sex, by color, and by annual family income

Age, sex, color, and income Number of cases (unweighted)

All arthritis

Osteoarthritis

Rheumatoid arthritis

Other forms of arthritis

127

104

11

12

Rate per 1,000 persons (based on weighted number of cases) All arthritis Age Under 15 15-34 35-64 65 and over Sex Male Female Color White Nonwhite Annual family income 1 Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over 1

75.2

66.3 -

-

(5.2) 98.6 514.9

3.5 -

5.3 -

84.2 487.2

(0.3) (7.9) (6.4)

(4.9) (6.5) (21.3)

44.4 103.0

37.0 92.7

(3.2) (3.8)

(4.1) (6.4)

84.1 51.9

76.2 40.4

(2.5) (6.3)

(5.4) (5.2)

138.5 69.1 68.0 51.3

111.7 67.0 62.6 46.5

(5.3) (1.6) (4.5) (4.1)

(21.5) (0.5) (1-0) (0.8)

-

Excludes cases for whom income was unknown.

justing for age differences changes the rate only a little, to 85 and 41 per 1,000, respectively. Prevalence by color. Osteoarthritis was nearly twice as prevalent among white persons (76 per 1,000) as among nonwhites (40 per 1,000). The disease was most common among aged persons, however, and the age difference between the two color groups more than accounts for the difference in prevalence. The age-adjusted rate for whites is 74 per 1,000—a little less than the 81 per 1,000 for nonwhites. Prevalence by income group. People in the lowest family income group (under $2,000) had arthritis (all forms) at a rate about twice as great (139 per 1,000) as the rate for the three higher income groups. Part of this difference is due to the fact that the lowest income group included a large proportion of older persons, among whom arthritis is, of course, most prevalent. Adjustment for age eliminates much of the difference in prevalence among income groups, but the rate for the lowest group remains above that for any other group. Table 37 shows the prevalence rates of all forms of arthritis, unadjusted and age-adjusted, by annual family income.

95

PREVALENCE OF SELECTED DISEASES TABLE 37.

Prevalence of arthritis, by annual family income (unadjusted and ageadjusted) Number of cases (unweighted)

Income group All incomes1 Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over 1

Rate per 1,000 persons (based on weighted number of cases) Unadjusted

Ageadjusted

75.2 138.5 69.1 68.0 51.3

75.2 94.2 73.2 81.6 52.8

127 35 31 27 13

Includes cases for whom income was unknown. TABLE 38.

Year of first symptom of substantial cases of arthritis

Year of first symptom Total 1954 1953 1952 1951 1950 1945-1949 1940-1944 1930-1939 Before 1930 Unknown

Percentage distribution (based on weighted number Weighted of cases)

Number of cases Unweighted 65 1 4 4 4 1 9 15 8 4 15

393.1 23.4 7.9 16.8 15.4 10.3 34.2 73.8 75.3 18.9 117.1

100.0 6.0 2.0 4.3 3.9 2.6 8.7 18.8 19.2 4.8 29.8

Severity and Duration The examining physicians classified 45 per cent of the arthritis cases as substantial in the sense that they were or might become handicapping or that they required or might require care. Of these substantial cases, 83 per cent were regarded as progressive and 13 per cent as stationary. For 3 per cent the extent of activity of the disease was undetermined. The substantial cases of arthritis tended to be of relatively long standing, as shown in Table 38, with first symptoms known to have appeared at least 10 years ago in more than 4 out of 10 cases. MENTAL DISORDERS

Prevalence Data from this study indicated a rate of 109 mental disorders per 1,000 persons in the noninstitutional population. Half of the cases were psychoneuroses (53 per 1,000), and one third (37 per 1,000) "psychophysiologic autonomic and visceral disorders," which may be described as

96

V O L U M E A N D CHARACTER OF CHRONIC DISEASE

psychoneuroses with somatic (physiologic) manifestations. The remainder of the cases included psychoses, mental deficiency, alcoholism, and other mental disorders. The method of arriving at diagnoses probably is a more significant factor in the data on prevalence of mental disorders than in the data on prevalence of most other diseases discussed in this report. The examining internists diagnosed a mental disorder as they chose, with or without a psychiatric consultation or psychometric testing. In some cases a psychiatric record was available. It was recognized that there would be differences in physicians' interest in and willingness to diagnose mental disorders. The records, therefore, were subsequently reviewed by a psychiatrist and classified by diagnosis and severity of impairment in accordance with the manual of the American Psychiatric Association.® In this review, there became apparent substantial differences among examining physicians in the completeness of recording of information bearing on mental disorders. The review resulted in the deletion of about one third of the cases which had been diagnosed by examining physicians, on the basis that the information recorded did not adequately support the diagnosis. To the extent that the deletion of cases by the reviewing psychiatrist was due to incomplete recording of evidence by the examining physician, the data presented here understate the prevalence. Mental disorders which were no longer present were also excluded from the data. Table 39 shows the prevalence of mental disorders as found in the study, by age, sex, color, and annual family income. Prevalence by age. The prevalence of mental disorders among this noninstitutional population was highest among persons aged 15 to 34 (148 per 1,000), and declined a little with increasing age to 115 per 1,000 for persons aged 65 and over. The rate for psychoneuroses was similar (about 70 per 1,000) for the three groups aged 15 and over, but much lower for children under 15, while the rate of the related psychophysiologic autonomic and visceral disorders declined with increasing age from 79 per 1,000 at ages 15 to 34 to none among aged persons. Psychoses were few in number but showed definite increase with advancing age. Prevalence by sex. Mental disorders as a whole occurred more often among women (131 per 1,000) than among men (84 per 1,000). Psychoneuroses and psychophysiologic autonomic and visceral disorders " Diagnostic and Statistical Manual, Mental Disorders, American Psychiatric Association, 1952.

p. 49. Washington, D.C.,

PREVALENCE OF SELECTED DISEASES TABLE 39.

97

Prevalence of mental disorders, by age, by sex, by color, and by annual family income

Age, sex, color, and income

Number of cases (unweighted)

All mental disorders

Psychoses

Psychoneuroses

Psychophysiologic autonomic and visceral disorders

111

17

51

18

Other mental, psychoneurotic, and personality disorders 25

Rate per 1,000 persons (based on weighted number of cases)

1

52.6

36.5

(0.4) (5.8) 27.8

(8.3) (68.8) 69.2 (70.8)

78.7 38.6

84.3 130.6

(6.0) 2.7

35.6 68.0

(18.9) 52.4

(23.8) (7.5)

Color White Nonwhite

122.8 71.5

5.8 (0.3)

62.2 (27.5)

43.7 (17.7)

(11.1) (26.0)

Annual family income1 Under $2,000 $2,000-$3,999 $4,000-$5,999 $6,000 and over

119.1 88.6 88.8 135.8

(4.1) (8.7) (1.5) (0.8)

(80.1) 55.4 (13.4) (62.5)

(18.2) (47.2) (72.5)

All mental disorders

108.6

4.3

Age Under 15 15-34 35-64 65 and over

34.2 148.3 131.7 114.9

Sex Male Female

-

-

-

-

15.2 (25.9) (0.4) (18.1) (16.3)

(34.9) (6.3) (26.7) -

Excludes cases for whom income was unknown.

were found to occur predominantly in females; but for all other mental disorders the prevalence was lower for females than for males. Because the various types of mental disorders had differing age patterns of prevalence, adjusting for age had little effect on the rates for males and females for all mental disorders. Prevalence by color. Mental disorder was diagnosed two thirds again as often for white persons (123 per 1,000) as for nonwhite persons (72 per 1,000). The substantially higher rates among whites for psychoses and psychoneuroses (including those with somatic manifestations) more than offset the preponderance among nonwhites of other mental disorders —behavioral disorders, mental deficiency, and alcoholism. Prevalence by income group. Persons in the lowest and the highest family income groups had more mental disorders (all types combined)

98

VOLUME AND CHARACTER OF CHRONIC DISEASE

than did persons in the two middle groups. The only disease group showing a continuous trend in relation to income was psychophysiologic autonomic and visceral disorders, which increased in prevalence directly with increased income from none in the under $2,000 income group to 73 per 1,000 in the $6,000 and over group. If these disorders are combined with the closely related psychoneuroses, however, this direct relationship disappears because of the high prevalence of psychoneuroses among persons in the lowest income group. Most of these rates were based on small numbers of cases and an explanation of the distribution by family income group is not readily evident from the data. Severity

When the records of cases diagnosed as having mental disorders were reviewed by the psychiatrist, they were classified by severity of impairment into 5 categories in accordance with the classification and definitions of the American Psychiatric Association.10 The distribution of the cases among the 5 categories and the definitions of these categories are shown in Table 40. Only among the psychoses, which were few in number, was a large proportion (two thirds) of the cases in the severe impairment category. The psychoneuroses and the psychophysiologic autonomic and visceral disorders were concentrated in the no impairment, minimal, and mild impairment categories. One out of 5 cases diagnosed as mental disorder was well adjusted to such a degree that there was no medical reason to change the employment or life situation. Characteristics

of Cases of Mental

Disorder

Examining physicians were asked to make a number of judgments in regard to duration, course, preventability, and prognosis for patients with mental disorders. One of the pertinent findings was the large number of cases in which the physician found it necessary to record the answers to these questions as "unknown." The examining physicians experienced great difficulty in estimating the duration of mental disorders. So great was their reluctance to identify the year of first symptom that for three fourths of the cases "unknown" was recorded. For those cases for which this question was answered, the distribution was rather even, showing no predominance of either recent or old cases. One sixth (16 per cent) exhibited their first symptom 10 or more years ago. An effort was also made to estimate the general course of the mental 10

Ibid.

99

PREVALENCE OF SELECTED DISEASES TABLE 40.

Mental disorders classified by severity of impairment as defined by the American Psychiatric Association 1

Diagnosis

Number of cases (unweighted)2

All mental disorders Psychoses Psychoneuroses Psychophysiologic autonomic and visceral disorders Other mental, psychoneurotic and personality disorders

Total

108 17 50

100.0 100.0 100.0

18

23

Percentage distribution (based on weighted number of cases) None Minimal Mild Moderate Severe 19.6 20.5

35.6 3.6 47.8

31.6 6.5 22.8

6.6 22.7 6.0

6.5 67.2 2.8

100.0

23.2

34.1

35.3

1.8

5.5

100.0

12.9

2.7

63.6

16.7

4.0

-

1

None: cases in which there are no medical reasons for changing employment or life situation. Minimal: cases with incapacity of perceptible degree and in terms of percentage not to exceed 10 per cent. Mild: impairment in social and occupational adjustment, such as 20 to 30 per cent disability. Moderate: a degree of impairment which seriously but not totally interferes with the patient's ability to carry on his pre-illness social and vocational adjustment, such as a 30 to 50 per cent disability. Severe: a degree of impairment which, for practical purposes, prevents the patient's functioning at his pre-illness social and vocational levels. Over 50 per cent disability. 2 Excludes cases of unknown severity.

disorder from first symptom to the time of examination. The answer to this question was "unknown" for 47 per cent of the cases, "progressive" for 19 per cent, "stationary" for 26 per cent, and "retrogressive" for only 8 per cent. Could progression of the condition to the present stage have been prevented by application of present-day knowledge and techniques? Again, the unknowns account for the largest group—58 per cent. Twenty-seven per cent were classed as preventable and 15 per cent as nonpreventable. Only one case was expected to improve without the recommended therapy, and for 43 per cent the prognosis without treatment was unknown. Improvement was predicted for only 13 per cent with therapy, and for 68 per cent prognosis with therapy was unknown. The attitude toward treatment was recorded as favorable for 23 per cent of the patients, mixed (i.e., some favorable and some unfavorable attitudes) for 12 per cent, unfavorable for 10 per cent, and unknown for 55 per cent. The judgments described were made by the internists rather than the psychiatrist and were based on only one or two contacts with the patient. As mentioned earlier, previous psychiatric records were available for

100

V O L U M E A N D C H A R A C T E R O F C H R O N I C DISEASE

some patients. For a small number (14 patients) a psychiatric consultation was ordered by the examining physician and then obtained as a part of the clinical evaluation. The evidence of this study indicates that qualitative judgments about the duration, prognosis, and response to therapy are difficult to make in the field of mental disorders; and that a different kind of work-up, perhaps including skilled observation over a period of time, would be necessary to obtain answers to the types of questions asked by the study. SYPHILIS

Prevalence The prevalence of syphilis was found to be 37 cases per 1,000 population. Over three fourths of these cases were late latent syphilis, with a stated history of disease having occurred 2 or more years ago and with a positive serologic test remaining as evidence of the latent presence of the disease. The other one fourth included 3 congenital, 6 cardiovascular, and 9 cases of central nervous system syphilis. The rates by age, sex, color, and annual family income are shown in Table 41. The data on which Table 41 is based include all cases in which there was both a positive serologic test TABLE 41.

Prevalence of syphilis, by age, by sex, by color, and by annual family income Age, sex, color, and income

Number of cases (unweighted)

Rate per 1,000 persons (based on weighted number of cases)

42

36.5

Total

1

Age Under 15 15-34 35-64 65 and over

7 27 8

23.8 63.9 79.0

Sex Male Female

17 25

34.9 38.0

Color White Nonwhite

9 33

10.1 105.9

Annual family income1 Under $2,000 $2,000-$3,999 $4,000-$ 5,999 $6,000 and over

17 11 5 1

64.8 37.3 (14.7) (14.9)

-

Excludes cases for whom income was unknown.

-

PREVALENCE OF SELECTED DISEASES

101

for syphilis and a reactive treponema pallidium immobilization test, and cases in which there was both a positive serologic test and a stated history of either genital lesion or treatment for syphilis. Prevalence by age. No cases of syphilis were found among children under 15. Modern methods of treating syphilis and the increased availability of prenatal care in Baltimore has substantially reduced the prevalence of congenital syphilis. The prevalence of the disease increased sharply with increasing age from 24 per 1,000 at ages 15 to 34, to 79 per 1,000 at ages 65 and over. Several factors appear to contribute to this increase : ( 1 ) older persons have had a longer opportunity to become infected; (2) many persons now in the older age groups contracted syphilis during the years when therapeutic methods of treating early syphilis were less effective; (3) persons now in the younger age group benefit from practices which were not available when their elders were young—notably improved casefinding techniques which result in earlier and more effective treatment; (4) the reduction of infectious contacts in recent years. Prevalence by sex. The prevalence of syphilis was about the same among men and women; it was higher among young women than young men, and higher among older men than among older women. Adjustment for age differences has little effect on the prevalence rates for men and women. Prevalence by color. Among the nonwhite population of Baltimore (about one fourth of the total population of the city) the prevalence of syphilis was found to be 106 per 1,000, as compared with a rate of 10 per 1,000 for whites. Adjustment for age differences increases the disparity in rates to 124 per 1,000 for nonwhites compared with 10 per 1,000 for whites. Prevalence by income group. People in the lowest family income group (under $2,000) had syphilis at a rate of 65 per 1,000; the rate dropped to 37 per 1,000 for persons with a family income of $2,000 to $3,999, and to 15 per 1,000 for persons in the two higher income groups. This distribution by income group can be explained by the finding that nonwhites had a much higher prevalence of syphilis than whites, and that the proportion of nonwhites in the lower income groups was much higher than the proportion of whites.

102

VOLUME A N D CHARACTER OF CHRONIC DISEASE TABLE 42.

Year of diagnosis of cases of syphilis

Year of diagnosis

Total 1954 and 1955 1953 1952 1951 1950 1945-1949 1940-1944 1930-1939 Before 1930 Unknown

Years since diagnosis XX

0 1 o 3 4 5-9 10-14 15-24 25 and over XX

Percentage distribution (based on weighted number of cases) 100 40 1 -

16 12 25 4 1

Duration The majority of the cases of syphilis had been diagnosed many years ago. Table 42 shows the distribution of cases by the year of diagnosis and by the number of years since diagnosis. The cases diagnosed in 1954 and 1955—40 per cent of the total—were newly discovered at the clinical evaluation. In the main these were asymptomatic, latent cases detected as a result of routine serologic tests, but included one case each of neurosyphilis and cardiovascular syphilis. Forty-one per cent of all cases had been diagnosed 10 years or more ago. No cases of early syphilis or early latent syphilis were found. These findings are consistent with those expected for a condition which formerly had a fairly high incidence but which has been brought under relatively good control by a combination of early detection and effective treatment. Two thirds of the cases were regarded as substantial, in the sense that they were or might become disabling or required or might require care. Prevalence of Historical Syphilis Cases with a history of treated syphilis but with negative serologic tests were excluded from these data. If they had been included, the resulting prevalence rate would have been 64 per 1,000, an increase of more than two thirds. The comparison of the rates including or excluding the strictly historical syphilis is shown in Table 43, which also presents prevalence rates by type of syphilis. These data undoubtedly understate the prevalence

103

PREVALENCE OF SELECTED DISEASES TABLE 43.

Prevalence of syphilis, by type

Number of cases (unweighted) Diagnosis

All syphilis Congenital syphilis Cardiovascular syphilis Syphilis of central nervous system Late latent syphilis

ρ

τ

Excluding historical1

Rate per 1,000 persons (based on weighted number of cases) Total·

Excluding historical1

69 3 6

42 2 6

64.0 (1.6) 2.0

36.5 (1.4) 2.0

9 51

8 26

8.6 51.8

8.1 25.0

1 "Total" includes cases with a history of treated syphilis, but with negative serologic tests at time of examination; these are omitted from "excluding historical."

of historical syphilis, since it is probable that some persons with a history, who expect their serologic test will be negative, would deny the history. The results, however, are of interest as an indicator of the effectiveness of treatment in producing a negative serologic test.

CHAPTER 5 PREVALENCE OF DENTAL CONDITIONS

Findings of the Study Discussion

108 117

Chapter

5 Prevalence of Dental

Conditions

Although there is a wealth of information describing the characteristics of dental disease and dental conditions among children, very little data are available describing adult populations. Most of the studies of dental diseases and conditions in adults have been conducted among special groups or for special purposes. For example, those conducted by the American Dental Association in 1940, and again in 1952, provided information about individuals who came to private dental offices for dental service.1 These data were obtained from highly selected groups of adults who perhaps had more need for dental service than the general population, who were conscious enough of their dental needs to seek such a service, and who undoubtedly represented upper income groups. A considerable amount of information has been published describing the dental conditions of adult personnel in the various military establishments. These data were obtained from selected male population groups who had survived a screening that included certain dental requirements. Other data are available from studies of the prevalence of oral disease in selected groups such as adult Public Health Service beneficiaries and special industrial employee groups.2 Perhaps the most broadly representative adult group for which published data exist comprises the 12,000 Metropolitan Life Insurance employees whose dental status was reported by Hollander and Dunning in 1939. 3 'American Dental Association, Bureau of Economic Research and Statistics. "Survey of Needs for Dental Care." Journal of the American Dental Association 45:706-712, December 1952; 46:200-211, February 1953; 46:562-571, May 1953; 47:206-213, August 1953; 47:340-348, September 1953; 47:572-574, November 1953. 2 One of these is a study of the prevalence of periodontal disease among the employees at the Home Office of the Metropolitan Life Insurance Company in New York City. It is reported by Dr. Walter A. Bossert and Herbert H. Marks in the Journal of the American Dental Association, April 1956, under the title "Prevalence and Characteristics of Periodontal Disease in 12,800 Persons under Periodic Dental Observation." " Hollander, Franklin, and Dunning, James M., D.D.S. "A Study by Age and Sex of the Incidence of Dental Caries in Over 12,000 Persons." Journal of Dental Research 18:43-60, February 1939. 107

108

VOLUME A N D CHARACTER OF CHRONIC DISEASE

Much additional information is needed about the dental health status and the dental needs of the general adult population to permit better identification of the nature and scope of the dental health problem in the United States. With the exception of cleft lip and cleft palate, which are recorded on birth certificates, none of the oral diseases or conditions are recorded officially. The epidemiologic character of these conditions can therefore be clarified by data obtained in surveys of representative population groups. Eventually, enough data may be made available from these sources to provide a basis for determining the level of dental illness and the amount of dental need in this country. The Baltimore Health Survey offered an unusual opportunity to gather data on dental conditions in an adult population group (aged 16 or older) drawn from a major metropolitan area. Consequently, dental investigation was included in the household interview, the clinical evaluation, and the screening procedure. This chapter presents the dental findings obtained as part of the clinical evaluation and the screening procedure. Data were recorded classifying the condition of each tooth as decayed, missing, indicated for extraction, filled, or present with no defect; on the condition of the soft and bony supporting tissues, classified as normal, or as showing evidence of gingivitis, periodontitis, and periodontosis; and on occlusion, classified according to angle. Observations on the condition of dentures and other prosthetic replacements and on the repair of cleft lips and palates were also noted. The anatomic location of certain soft tissue conditions, such as inflammation, ulceration, swelling, induration, and leukoplakia, was recorded.4 A copy of the dental record card used in the survey is contained in Appendix H, s together with related material.

FINDINGS OF THE STUDY

A total of 2,050 adults received dental examinations, 1,622 at the dental station of the screening procedure and 428 during the clinical evaluation. Twenty-two per cent of those examined were nonwhite, and 78 per cent white. There were 947 males examined and 1,103 females. The age, color, and sex distributions of the dental examinees were very similar to the distributions of the household survey sample as shown in Table 44. 1 Definitions of a number of the terms used in this paragraph are contained in Appendix H, Exhibit XIX. 5 Exhibit XX.

P R E V A L E N C E OF D E N T A L CONDITIONS TABLE 44.

109

Comparison of dental examinees aged 25 to 74 and the household survey sample, by age, by sex, and by color 1 Percentage distribution Age, sex, and color

Household survey sample

Dental examinees

Ages 25 to 742 25-34 35—44 45-54 55-64 65-74

100.0 27.0 26.7 21.8 15.4 9.1

100.0 26.6 31.6 21.0 14.3 6.5

Both sexes Male Female

100.0 47.2 52.8

100.0 46.4 53.6

White and nonwhite White Nonwhite

100.0 75.1 24.9

100.0 78.0 22.0

1 Additional tabular material relating to this and other aspects of the dental study appears in Appendix F. 2 Persons under 25 are omitted because the lower age limit of persons differed from the household survey classification by age.

Decayed,

Missing, and Filled

Teeth

Among the sample of the adult population examined, more than half (16.8 teeth per person) of the full normal complement of 32 teeth were either decayed, missing, or filled. Table 45 shows the status of the full complement of 65,600 teeth of the 2,050 examinees. DMF rates as related to age and color. Table 46 and Figure 5 present this same information in a different manner. They show the status of the teeth per person (DMF rate). Most of the affected teeth were missing (11 teeth per person), a large number were filled (5 teeth per person), and a relatively small number decayed ( 1 tooth per person). The prevalence of dental disease as expressed in terms of decayed, missing, and filled teeth among persons under 35 years of age primarily reflects dental caries activity, with periodontal disease contributing inTABLE 45.

Status of full complement of teeth of dental examinees Status

Number of teeth

Percentage oí total

Full complement of teeth Decayed Missing Filled Present, no defect

65,600 2,294 21,475 10,633 31,198

100.0 3.5 32.7 16.2 47.6

110

VOLUME AND CHARACTER OF CHRONIC DISEASE

FIGURE 5.

D M F rates, b y a g e

30

25

c o to

Χ

fc 20 CL

y

0) Q.

DMF/ y

% 15

/

υ

«4-

o

/ /

/

S

/

3 Ζ 5

F D

0

Under 25

25-34

35-44

45-54

55-64

65-74

Age

creasingly to the number of missing teeth as the individual grows older. The data show a consistent increase with age in the average number of decayed, missing, or filled teeth per person. In the white population aged 25 to 34, approximately 15 teeth per person were found to be decayed, missing, or filled, whereas 17 teeth per person were so classified in the 35 to 44 age group. There was a continuing increase of 2 teeth or more each 10 years throughout the age span examined, reaching nearly 25 teeth per person in the 65 to 74 age group. In the white and nonwhite population combined, the average number of decayed (unfilled) teeth decreased steadily with increasing age from 2.4 per person under age 25 to 0.2 per person aged 65 to 74. The number of filled teeth per person was highest in the 25 to 34 age group (7 per person) and decreased steadily thereafter to 3 per person aged 65 to 74. This was accompanied by a sharp increase in the rate of missing teeth from 4 per person under 25 to 21 per person aged 65 to 74. A significant portion of this DMF increment is due to the increased number of teeth lost because of periodontal disease, although the exact portion is impossible to determine. In the absence of complete dental histories, examination at any point in time will not usually disclose the

PREVALENCE OF DENTAL CONDITIONS TABLE

46.

DMF index (over-all DMF rates and rates for DMF components), by age and color DMF1

Age group

Total 1 Under 25 25-34 35—44 45-54 55-64 65-74 Total 1

111

No. of examinees

2,050 199 492 584 389 265 121

No. Rate peri of teeth person 34,402

No. Rate per of teeth person

White and nonwhite 16.8 2,294 1.1

2,221 11.2 6,564 13.3 9,318 16.0 7,666 19.7 5,707 21.5 2,926 24.2

M3

F

£>3

No. Rate per of teeth person 10,633

476 674 680 290 145 29

2.4 1.4 1.2 0.7 0.5 0.2

941 3,281 3,521 1,794 785 311

White 1,330

No. Rate per of teeth person

5.2

21,475

10.5

4.7 6.7 6.0 4.6 3.0 2.6

804 2,609 5,117 5,582 4,777 2,586

4.0 5.3 8.8 14.3 18.0 21.4

1,573

28,271

18.0

0.8

10,004

6.4

16,937

10.8

Under 25 25-34 35—44 45-54 55-64 65-74

129 375 457 308 209 95

1,656 5,584 7,868 6,199 4,637 2,327

12.8 14.9 17.2 20.1 22.2 24.5

240 1.9 416 1.1 407 0.9 175 0.6 81 0.4 11 0.1

869 3,071 3,318 1,713 736 297

6.7 8.2 7.3 5.6 3.5 3.1

547 2,097 4,143 4,311 3,820 2,019

4.2 5.6 9.1 14.0 18.3 21.3

Total 1

477

6,131

12.9

Nonwhite 964 2.0

629

1.3

4,538

9.5

Under 25 25-34 35-44 45-54 55-64 65-74

70 117 127 81 56 26

565 980 1,450 1,467 1,070 599

8.1 8.4 11.4 18.1 19.1 23.0

236 3.4 258 2.2 273 2.2 115 1.4 64 1.1 18 0.7

72 210 203 81 49 14

1.0 1.8 1.6 1.0 0.9 0.5

257 512 974 1,271 957 567

3.7 4.4 7.7 15.7 17.1 21.8

1 The rate of decayed, filled, or missing teeth for all age groups combined is the total number of teeth in these categories divided by the number of persons examined. Reports on some studies of dental defects use the average of the rates for the age groups as the rate for all ages combined. 2 Includes decayed teeth and teeth that were both decayed and filled. 8 Includes missing teeth and teeth indicated for extraction due to caries or periodontal disease.

reason for the loss of teeth not then present. Usually the loss must be ascribed to one or both of two factors—caries activity and periodontal disease. Nevertheless, a considerable portion of the loss must be directly imputed to dental caries. For example, in the age group 25 to 34, an average of 1.4 teeth per person showed evidence of unrepaired decay, as compared with an average of 0.5 classed as carious in the age group 55 to 64. While it is impossible to determine the extent to which these findings represent new decay, as differentiated from residual or accumulated neglect, it is apparent that caries continues to be a problem in older age groups.

112

V O L U M E A N D C H A R A C T E R OF C H R O N I C D I S E A S E

While the missing tooth rates for white and nonwhite groups were about the same, the difference in caries experience was marked. For instance, white persons aged 25 to 34 had an average of 9 decayed and filled teeth (known to have or have had caries) whereas the nonwhite group of the same age had an average of 4 decayed and filled teeth per person. At older ages, the over-all DMF rates were nearly equal for the two groups, largely because of the increased effect of periodontal disease upon the missing tooth rate in both groups, and also because of the consistently low filled tooth rate for nonwhites of all ages. The over-all DMF rate for whites (18) was nearly half again as great as the rate for nonwhites (13). DMF rates as related to sex and income. Dental disease prevalence among the white examinees, as measured by the DMF index, was approximately the same for males and females, with the females exhibiting a slightly higher rate. There was no significant difference between males and females in the component parts of the index. The prevalence of the various dental conditions, measured in terms of the average number of decayed, missing, or filled teeth per person, was approximately the same among high, medium, and low income groups. There was quite a difference, however, in the distribution of the DMF components. This difference reflected economic status and the individual's ability to purchase dental services. Table 47 shows the DMF rates for whites by sex and annual family income. The filled tooth rate among whites was 5 for the low income group in comparison with 9 for the high income group. The reverse is TABLE 47.

D M F rates among white persons and rates for D M F components, by sex and by annual family income

1

DMF rate per person

Number of dentai examinees

Total

D

M

F

Both sexes Male Female

1,573 741 832

18.0 17.5 18.4

0.8 1.0 0.8

10.8 10.7 10.9

6.4 5.9 6.8

All incomes Low 1 Medium 2 High3

1,573 606 537 430

18.0 18.7 17.3 17.9

0.8 1.1 0.8 0.6

10.8 13.0 10.1 8.5

6.4 4.6 6.4 8.9

Sex and income

Under $4,000. $4,000 to $5,999. 8 $6,000 and over. For analytical purposes the white examinees were divided arbitrarily into these three income groups. The only criterion for these divisions of income was that the three groups be of approximately equal size. 2

P R E V A L E N C E OF D E N T A L C O N D I T I O N S

113

seen in an analysis of missing teeth, where the rates were 13 in the low income group, and 9 in the high income group. It is of interest to note (Appendix F ) that the missing tooth rate among persons under 25 years of age was 5 times as high in the low income group as in the high income group. Another marked difference in dental health status was the fact that the filled tooth rate in the nonwhite group was about one fifth as high as in the white group; this difference is shown in Table 46, and is presumably the result, in part at least, of low income or educational levels. Needs for Dental

Treatment

An important and realistic method of evaluating the dental health of a population consists of measuring its total unmet dental needs. At the time of examination, 80 per cent of the white examinees had some dental condition requiring professional service—fillings, extractions, prosthetic replacements, or periodontal treatments exclusive of simple prophylactic needs—while only 20 per cent needed no treatment. More than half (12 per cent of the 20 per cent) of those needing no treatment were in possession of full dentures (see Table 48). An interesting fact which does not show in Table 48 is that only 7 per cent of the persons who did not wear dentures needed no treatment. Seven out of 10 persons needed replacement of one or more teeth, not including those for whom a full denture would be the replacement. About 4 out of 10 needed treatment of a periodontal condition (44 per cent) and needed one or more teeth filled (38 per cent). Smaller proportions needed extractions (17 per cent) and dentures (6 per cent). This tremendous backlog of unmet need for dental service is detailed in Table 49. Differences were small between males and females in the number of persons needing treatment as well as in the kind of treatment needed— although more males than females needed treatment. Larger proportions TABLE 48.

White dental examinees needing no dental treatment, by sex Examinees with full dentures

Sex

Total Male Female

Number of examinees

1,573 741 832

Examinees not needing treatment """"""" Percentage Number of number examined 309 142 167

19.6 19.2 20.1

PercentNumbgr

195 91 104

Percentage , examined

12.4 12.3 12.5

of

those needm S no treatment 63.1 64.1 62.3

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PREVALENCE OF DENTAL CONDITIONS

115

of nonwhites than whites needed each of the five types of dental treatment. For extractions, the proportion was three times as great, and for fillings twice as great. The relationship of income level to dental health noted earlier is clearly apparent in the need for dental care. Among whites the proportion needing each type of treatment, except replacement, decreased substantially with increasing income. One would expect persons with family incomes of $6,000 or more to be able to pay for ordinary dental care. Yet nearly one fourth of the examinees in the high income group (23 per cent) needed fillings, suggesting that attitudes toward dental care, rather than cost, may be partially responsible for failure to secure care. Despite the fact that the proportion needing each of four of the five types of care increased substantially with decline in income level, the proportion of people needing any one or more types of care changed little with income level; this is probably because persons in the low income group needed two or more types of service more often than did people in the higher income groups. The 2,050 examinees had an average of 1 tooth per person needing filling, 0.7 needing extraction, and 4 needing replacement (Table 50). The sum of these averages is about 6 teeth per person needing some kind of treatment. The averages for males and females were nearly identical; there were only slight differences in the types of treatment needed. The average number of teeth per person needing treatment of all three types mentioned above was much higher for nonwhites (8) than for whites ( 5 ) , and there were differences in the types of treatment needed. Nonwhites had about three times as many teeth needing extraction as did white persons, and more than twice as many needing filling, but only a slightly larger number needing replacement. The relationship of income to dental health is again reflected in the figures on unmet needs for treatment per examinee. For example, white examinees of both sexes in the lowest income group had an average of 1.1 teeth per person needing filling, but in the highest group only 0.6. The relationship is most striking for teeth needing extraction, where the low income group had seven times as many teeth per person needing extraction as the high income group. Prevalence of Periodontal

Conditions

The periodontal tissues were classified as normal, or as showing evidence of gingivitis, periodontitis, or periodontosis. The proportion of patients

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Per cent

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Similar results are obtained using the percentages at or above other levels, and by using medians. It appears that although the diastolic pressure increased less with advancing age than did the systolic pressure, the increase began at an earlier age. Heart Disease The electrocardiogram. An electrocardiogram was taken .for each person evaluated who was aged 18 or over, and for younger persons at the re-

SCREENING FOR CHRONIC DISEASE

247

quest of the examining physician. The three standard limb leads and the three chest leads (V 1, V 3, and V 5) were run routinely, with six chest leads run on request. The electrocardiogram was carried out in the evaluation clinic by a laboratory technician who had been trained in the technique by the Heart Station of the hospital. The electrocardiograms were interpreted by the cardiologists of the Heart Station. The revised recommendations of the Framingham Epidemiological Study19 were used as guides in classifying the tracings. Findings on the 571 adults who had electrocardiograms made in the evaluation clinic are given in Table 76. On the basis of the weighted data, 126 per 1,000 persons had positive EKG's and 70 per 1,000 were subsequently diagnosed as having some type of heart disease—of which 41 per 1,000 were previously unknown cases and 30 per 1,000 were old or known cases. The distribution by age indicates that the largest yield of positive tests and of diagnosed new cases was in the age group 65 and over. However, in the age group 45 to 64, the rate of new cases found was 66 per 1,000—a rate which would clearly justify screening in this age group. It is also necessary to consider the performance of the test in terms of missed cases, that is, false negatives. From Table 77 it will be seen that the 6 lead EKG classified 43 cases of heart disease as normal, a false negative rate of 8 per cent. It also wrongly classified 41 cases as positive, a false positive rate of 7 per cent (the percentage of weighted numbers was 6). These false positives were the people who, in a typical screening clinic procedure, would have been referred to their personal physician and who later, and after considerable anxiety and expense, would have been found to have no heart disease. Although the EKG detected a substantial number of new cases of heart disease, its weakness in terms of both false positives and false negatives was demonstrated. Chest x-ray (for detection of heart disease). The results of the use of the 70 mm. chest x-ray for detection of heart disease are shown in Table 78. The films were read by a chest physician for abnormality of the size or shape of the heart as well as for lesions of the lung parenchyma. The chest x-ray detected only about half as much heart disease as did the 6 lead EKG. Since it is generally agreed that the size and shape of the heart is not affected until the condition is fairly well advanced, chest x-ray cannot be expected to detect the early cases. Nevertheless, it is worth noting that the chest x-ray did detect previously undiagnosed heart disease at a rate of 20 cases per 1,000 population. Such a yield would appear to ™ See Appendix D.

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SCREENING FOR CHRONIC DISEASE

253

digitalis administration was not available; some changes may be accounted for by this drug. Τ wave and ST, ST-T segment abnormalities, which constituted three fourths of all abnormalities observed, showed a pattern of prevalence with regard to age similar to that noted above for all abnormalities combined. Τ wave abnormalities, however, were nearly twice as common among females as among males; while abnormal ST, ST-T segments were a little less common among females than among males. The few instances of right bundle branch block, intraventricular delay, right ventricular strain, and first degree heart block in persons under age 30 can be assumed to reflect the presence of rheumatic heart disease and congenital heart disease. As would be expected, left bundle branch block and left ventricular strain were found only in older persons, and probably were indicative of the higher frequency of coronary artery disease and hypertension in this age range. Auricular fibrillation likewise occurred exclusively in the older persons, and probably was predominantly of arteriosclerotic or hypertensive origin. It is somewhat surprising that younger individuals with rheumatic lesions did not show auricular fibrillation. The most interesting finding in the entire EKG study was the sex distribution of myocardial infarction. Both anterior and posterior wall infarctions were noted more commonly in females, though the number of cases was small. This can be better explained when one notes that the highest incidence occurred in the group over 65 years of age. This finding is consistent with previous observations that despite the preponderance of males showing clinical atherosclerotic complications in younger decades, in the population over 65 there is equalization between sexes, and that, pathologically, the females (surviving longer than males) even show a higher incidence of severe atherosclerosis. As shown in Table 81, a diagnosis of heart disease was made for only a little over half of the persons (52 per cent) whose electrocardiograms were interpreted as abnormal. Seven of the 11 types of abnormalities listed were found in one or more persons for whom heart disease was not diagnosed. For the two abnormalities most frequently found—Τ wave and ST, ST-T segment—the percentages of cases in which heart disease was not diagnosed were 57 and 55, respectively. Tables 82 and 83 show these percentages for males and for females. Heart disease was diagnosed much less frequently in females than in males with abnormal Τ waves. For abnormal ST, ST-T segment, the opposite was observed, but the difference was small.

254

SCREENING

TABLE 8 1 .

Electrocardiogram abnormalities in adults evaluated for whom heart disease was not diagnosed All abnormalities Number of persons

EKG abnormality

All abnormalities Abnormal Τ waves Abnormal ST, ST-T segment Posterior myocardial infarction Right bundle branch block Anterior myocardial infarction First degree block Auricular fibrillation Left ventricular strain Left bundle branch block Intraventricular delay Right ventricular strain 1

Abnormality, heart disease not diagnosed Percentage of Number of persons 0„ abnormalities Un(based on weighted Weighted weighted numbers)

Unweighted

Weighted

120 44

1,023.2 398.9

44 21

494.9 226.1

48.4 56.7

37

373.2

17

204.6

54.8

8.3

13.5

22.7

49.2

1.5 30.3

3.4 96.8

1

5

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TABLE 8 2 .

Abnormal Τ waves in adults evaluated for whom heart disease was not diagnosed, by sex All Τ wave abnormalities Number of persons

Sex

Un„, . , , weighted Weighted

Both sexes Male Female TABLE 8 3 .

44 15 29

398.9 122.8 276.1

Τ wave abnormality, heart disease not diagnosed Number of persons

Percentage of aU

abn0TmaMes

Unweighted

Weighted

(based on weighted numbers)

21 6 15

226.1 34.8 191.3

56.7 28.3 69.3

Abnormal ST, S T - T segment in adults evaluated for whom heart disease was not diagnosed, by sex Ail ST, ST-T segment abnormalities

Sex

Both sexes Male Female

ST, ST-T segment abnormality, heart disease not diagnosed

Number of persons

Number of persons

Unweighted Weighted

Unweighted

37 19 18

373.2 195.0 178.2

17 8 9

Weighted 204.6 116.3 88.3

Percentage of all abnormalities (based on weighted numbers) 54.8 59.6 49.6

SCREENING FOR CHRONIC DISEASE

255

Diabetes Mellitus Entirely different approaches to the detection of diabetes were employed in the clinical evaluation step and in the screening step. Because diabetes is such a classic example of a chronic disease susceptible to control, a rather full discussion of the disease and the different methods of screening for it has been included in Appendix D. Also described there is the somewhat novel use of a modified glucose tolerance test in the Baltimore multiple screening clinic. The data presented here are limited to the 601 adults who were examined in the evaluation clinic. The size of this group was small, but the data have the advantage of a complete diagnostic work-up of each case—which is lacking for the screening clinic cases. The tests employed were dictated by conditions under which the clinic operated. Because only a few patients were seen each day, it was not feasible to use the Clinitron, which is suitable only for mass operations. Also, it was not practical to arrange for evaluees to come in fasting. The tests for diabetes consisted of drawing venous blood and obtaining a specimen of urine approximately 30 to 60 minutes after the person's arrival at the clinic. The interval between the last meal and the venipuncture was recorded and was taken into consideration in the interpretation of the results. If the blood specimen was taken 3 hours or more since the last meal and was 110 mg. per cent or above, it was considered positive; if the specimen was taken not more than 1 hour since the last meal and was 140 mg. per cent or above, it was considered positive. Intermediate values were used for time intervals between 1 and 3 hours. The blood sugar determination was made by the hospital laboratory, employing the Folin-Wu method. Results on the 601 persons tested are given in Table 84. Examination of the weighted data shows that 63 per 1,000 of this noninstitutional population group were positive and that diabetes mellitus was diagnosed (usually by 2-hour glucose tolerance test) in 40 per 1,000. Approximately one third of these were previously known cases, and two thirds were previously unknown. It will be noted that the highest rate of previously unknown cases was in the 45 to 64 age group. The urine sugar determination test employed was Benedict's qualitative method, and in comparison with the blood sugar determination test it gave very poor results (Table 85). Only about one third of the previously known cases were positive to the urine sugar test, probably as a result of insulin therapy. Only one new case was detected. The contrast in the relative effectiveness of blood sugar and urine sugar testing is shown in

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PART V

Disability Reported by the General Population

CHAPTER 13 DISABILITY REPORTED IN HOUSEHOLD INTERVIEWS

One-Day Prevalence of Disability from All Conditions Four-Week Prevalence of Disability from All Conditions Twelve-Month Prevalence of Disability from Chronic Conditions Outstanding Relationships

270 271 280 289

Chapter

13 Disability Reported in Household Interviews In the household survey, information about the sample of 11,574 persons in the noninstitutional population 1 of the city was requested. The information sought concerned illness due to disease or injury (or the late effects of injury) existing on the day before the interview ("yesterday") and during the 4 weeks ending with yesterday ("the past 4 weeks"), and "chronic conditions" during the past 12 months. For chronic conditions (as defined on page 280 of this chapter) which were not reported as illness during the past 4 weeks or yesterday, the respondent to the interview was asked whether the condition had "bothered" the person during the past 4 weeks; if so, the condition was included in the data for the past 4 weeks, and for yesterday if the response was that it had also bothered him yesterday. Thus, for yesterday and for the past 4 weeks, the data gathered included conditions, acute and chronic, which had made the person sick or had bothered him without making him sick. Each condition was classified, for yesterday, according to whether it kept the person from his usual activities, kept him indoors, or kept him in bed; and, for the past 4 weeks, according to the number of days to which each degree of disability applied. A person with a static defect or impairment not causing illness was presumably reported as disabled by that defect only if in the respondent's opinion it did in fact keep him in bed, indoors, or from his usual activities. Age, sex, and other personal data were also recorded.2 Part VI of this report is devoted to a discussion of the lessons learned from this study and the improvements that could be made in similar projects in the future. Chapter 14 is specifically concerned with the grave 1 The large number of persons in medical institutions for long-term care are excluded; the smaller number of persons in nonmedical institutions such as orphanages and schools are included. 'The specific questions asked in these structured interviews are discussed in Appendix A.

267

268

DISABILITY REPORTS

weaknesses of the chronic disease prevalence data gathered from the household interviews. This study does, indeed, raise serious questions about the value of the household interview in assembling prevalence data on chronic disease, but it is believed that the reporting of disability was more complete than was the reporting of specific diseases in the household interviews. This belief could not be checked by comparing the interview reporting of disability with information gained in other ways (as was done in the case of the prevalence data, with the results shown in Chapter 14). There may not be any feasible technique for gathering data on disability which could be expected to produce results significantly more complete and accurate than the information obtained from the interviews. It is true that each person would have been reporting for himself in the clinical evaluation, rather than having another family member report for him. However, many of the possible sources of error in reporting disability that are inherent in household interviews would have been present also in the clinical evaluation.3 In addition, the gap between the dates of interview and evaluation—averaging nearly 4 months and in some cases as long as a year—would have hampered a comparison of disability data from the two sources more than it did the comparison of prevalence data. Despite the absence of proof, however, the belief that interview reporting was more complete for disability than for prevalence has a substantial basis in the assumption that people are able to report disability for themselves and members of their families more completely than they are able to report the names of the conditions causing the disability. The primary reason why this should be true is that disability is an extremely tangible, personal factor in the individual's life, and he knows better than any one else the nature and effect of his disability. This cognizance may be quite apart from a knowledge of the technical terminology which describes the disability or the name of the condition which may be causing it. Thus, whether or not he is receiving medical attention for the disabling condition, he can report his disability with assurance—whereas he may be either uninformed or comparatively unconcerned with the precise definition of the health condition which lies behind it. A second reason for believing that disability was more completely reported in household interviews than was prevalence has to do with the questions that were asked and the order in which they were asked. The questions asked about yesterday included: "Were you sick at all?" and 3 See Chapter 14. Some of the sources of error in interview reporting of diagnoses apply also to reporting of disability.

HOUSEHOLD INTERVIEW REPORTS

269

"Were you feeling as well as usual?" As the concept of being sick or not feeling as well as usual includes the concept of disability, these questions inquired about disability directly—and before the person was asked the name of the condition causing the disability. Most chronic conditions (as shown in Chapters 3 and 4) were continuous and had a relatively steady progressive course. Thus, questions about illness yesterday and during the past 4 weeks secured reports of many of the chronic conditions—and disabilities—present during the past 12 months. Questions asked specifically about the past 12 months included a general question about chronic conditions and impairments, so that a person with a disabling condition could answer "yes"—indicating that he had a condition —before being asked to name the condition. Still a third indication that the interview reporting for disability should have been better than that for prevalence is the evidence, both direct and indirect, from other studies which suggests that household interviews generally produce better data on disability than they do on prevalence of disease.4 In the light of these considerations, it is appropriate to present the disability5 data gathered in the household interviews. It is appropriate also to use as a basis the entire 11,574 persons on whom household interview reports were obtained, rather than the 809 of these people who made up the clinical evaluation sample. There is no purpose in confining the disability information to the 809-person sample, for no comparable information on disability was obtained in the clinical evaluation. There is an advantage in using the entire household interview sample: it permits the presentation of information on a representative noninstitutional population group 14 times as large as the clinical evaluation sample—and this, of course, reduces the sampling variability. The response rate in the interview survey was high (98 per cent), so that almost no bias due to nonresponse is encountered. Therefore, the disability data in this chapter are based on the household interview sample rather than on the clinical evaluation sample. The data which follow are concerned almost exclusively with the in1 Allen, George I., Breslow, Lester, M.D., Weissman, Arthur, and Nisselson, Harold. "Interviewing Versus Diary Keeping in Eliciting Information in a Morbidity Survey." American Journal of Public Health, 44:919-927, M y 1954. Also Collins, Selwyn D. "Sickness Surveys." In Emerson, Haven, M.D. Administrative Medicine, pp. 511-535. New York, Nelson, 1951. (Reprinted from Nelson LooseLeaf Medicine.) " The term "disabled" is used in this chapter in lieu of the more nearly accurate but unwieldy "reported to have been disabled" and is used to include all degrees of disability.

270

DISABILITY REPORTS

formation concerning disability gathered in the household interviews. They are in every case based on unweighted numbers of persons. They relate to all disability regardless of diagnosis, and are given in terms of persons disabled rather than in terms of conditions which were disabling.® For persons having a period of disability attributable to multiple conditions existing simultaneously, the duplication of days of disability has been removed. ONE-DAY PREVALENCE OF DISABILITY FROM ALL CONDITIONS

The one-day prevalence rates were derived from two sources: information gained in response to the questions about yesterday and in response to other questions which secured reports of conditions subsequently found to have been bothering the person yesterday. The one-day rates reflect the disability resulting from all conditions, both acute and chronic. One out of 7 persons (144 per 1,000) in the sample interviewed was either bothered or disabled by a health condition on the day preceding the interview; 29 per 1,000 persons were disabled—one fifth of those bothered. Half of the persons disabled (15 per 1,000) were kept in bed on the day preceding the interview (Table 91). More of the children under 15 (28 per 1,000) than of young adults (18 per 1,000) were disabled yesterday—about the same rate as for persons aged 35 to 64 (29 per 1,000). Many more aged persons (78 per 1,000) were disabled on the day before the interview. Disability was more prevalent among females (33 per 1,000 persons) than among males (26 per 1,000), and more females than males were kept in bed (17 per 1,000 compared with 12 per 1,000). A somewhat larger proportion of white persons (31 per 1,000) than of nonwhite persons (25 per 1,000) was disabled on the day before the interview. The proportion kept in bed was similarly higher for whites than nonwhites. Much of this racial difference in the proportions disabled was due to the previously noted fact that the white population was an older group than the nonwhite population, and there is more disability due to chronic disease among older people than among younger people. The proportion of persons disabled yesterday was about twice as high (52 per 1,000) in the lowest as in any higher income group. It was " T h e duration of disability, both total days and days kept in bed, during the past 4 weeks and during the past 12 months was recorded. An exhaustive number of tables can be derived relating duration of disability, by severity, to personal characteristics. F o r the use of those interested, basic data which permit the preparation of such tables appear in Appendix E. A few such tables are presented in this chapter as illustrations of particular points.

HOUSEHOLD INTERVIEW REPORTS TABLE

91.

271

Disability of persons bothered by one or more conditions on day preceding interview, by age, by sex, by color, and by annual family income Rate per 1,000 persons

Age, sex, color, and income

Number of persons interviewed

Disabled Bothered but not disabled

11,574

Total

Kept from usual activities

Kept indoors

Kept in bed

114.9

29.2

6.7

7.9

14.6

3,135 3,219 4,329 870

67.3 105.9 139.1 201.1

27.8 17.7 29.1 78.2

4.8 5.6 7.9 12.6

11.8 3.1 4.9 26.4

11.2 9.0 16.4 39.1

Sex Male Female

5,484 6,090

88.8 138.4

25.5 32.5

7.7 5.9

6.4 9.2

11.5 17.4

Color White Nonwhite

8,388 3,186

126.3 85.1

30.8 25.1

7.3 5.3

8.5 6.3

15.0 13.5

Annual family income Under $2,000 $2,000-$3,999 $4,00ft-$5,999 $6,000 and over Unknown

1,569 3,753 2,716 1,724 1,812

143.4 104.2 110.8 109.0 124.2

52.3 27.4 19.9 24.9 30.9

12.7 7.5 5.5 4.6 3.9

15.9 7.5 4.4 5.2 9.4

23.6 12.5 9.9 15.1 17.7

All persons1 Age Under 15 15-34 35-64 65 and over

1

Includes persons whose age was unknown.

lowest for the $4,000 to $5,999 group—the group next to the highest income. Of those disabled, the proportion kept in bed was greater among persons in the highest income group—three fifths—than among persons with lower annual family incomes. Rather than an absolute difference in medical condition, this may reflect a difference in attitude as to what degree of illness requires a person to stay in bed. The high prevalence of disability among the lowest income group may be due to the larger proportion of aged persons in this than in higher income groups. FOUR-WEEK PREVALENCE OF DISABILITY FROM ALL CONDITIONS

More than one tenth of the people (11 per cent) had been disabled one day or more during the 4 weeks preceding the interview by all conditions combined, acute and chronic. The proportion disabled one day or more was high for children and elderly people and lower for young adults and persons in the middle age ranges (Table 92). It was higher for women (13 per cent) than for men (9 per cent) and this held for all adult ages combined and for each age group. For children under 15 there

272

DISABILITY REPORTS

TABLE 92.

Persons disabled one or more days during 4 weeks preceding interview, expressed as a percentage of all persons interviewed, by age, sex, and color Age

AH ages1 Under 5 5-14 15-24 25-34 35-44 45-54 55-64 65-74 75 and over 1

Sex

Total 11.0 14.9 12.1 8.8 9.4 9.1 10.1 10.8 14.8 19.1

Color

Male

Female

White

9.1 13.7 12.4 5.7 6.0 6.6 8.1 8.2 13.5 16.1

12.8 16.3 11.7 11.0 12.5 11.5 12.1 13.1 15.7 20.6

12.0 17.9 14.9 9.6 9.8 9.4 10.6 10.6 14.6 19.1

Nonwhite 8.5 9.8 6.0 6.8 8.7 8.3 8.6 11.9 15.8 18.8

Includes persons whose age was unknown.

was little difference among boys and girls in the percentage having a disabling illness; for most adult age groups the percentage of disabled males was about half that of females, but for the aged the percentages were more nearly equal. Larger proportions of whites (12 per cent) than nonwhites (9 per cent) had one or more days of disability during the 4 weeks prior to the interview. The difference was greatest for children under 15. The proportion of persons disabled during the 4-week period was highest for the lowest income group. It was also slightly higher for the upper income groups than for the $2,000 to $3,999 group (Table 93). In each income group, persons between the ages of 15 and 64 were less frequently disabled than were either younger or older people. The duration of disability during the 4-week period for each age group is shown in Table 94. Sixteen per 1,000 persons were disabled at least 3 of the 4 weeks. Among the ages, the distribution ranged from 5 or less per 1,000 for persons under 25, to 101 per 1,000 persons aged 75 and TABLE 93.

Persons disabled one or more days during 4 weeks preceding interview, expressed as a percentage of all persons interviewed, by age and annual family income

Age All ages1 Under 15 15-34 35-64 65 and over 1

All incomes

Under $2,000

$2,000$3,999

$4,000$5,999

11.0 13.2 9.2 9.9 16.1

14.5 15.5 11.4 14.3 18.1

9.6 11.3 7.9 9.1 13.1

11.0 13.8 9.5 9.9 12.1

Includes persons whose age was unknown.

$6,000 Income and over unknown 11.9 19.4 10.0 8.4 18.2

10.0 9.0 8.8 9.7 17.0

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274

DISABILITY REPORTS

older. In the intervening age groups, advancing age was accompanied by a steady and nearly continuous increase in the rate of disability. Table 94 reveals the tendency in most interview reporting toward the use of round numbers and familiar time segments. Thus, 4 times as many persons were reported as having been disabled one week (7 days) as were disabled 6 days. This obviously is a quite unlikely situation. There were similar concentrations at 14, 21, and 28 days. In the data on duration of disability due to chronic conditions alone during the past 12 months (presented later), there were concentrations at multiples of 7, and for persons disabled longer periods, at multiples of 30. The proportion of females disabled almost continuously throughout the 4-week period was about half again as large as the proportion of males disabled almost continuously. Females were also more often disabled for each of the shorter durations, reflecting the more frequent disablement of women noted earlier. Similar differences—also noted earlier—existed between whites and nonwhites, with the proportion of whites exceeding that for nonwhites at each duration of disability. These differentials by sex and by color are probably due to differences in age distributions. The most striking characteristic of duration of disability by income group was the large proportion (38 per 1,000) of the lowest income group who were disabled at least 3 of the 4 weeks—nearly 4 times the proportion shown for any other income group.

Total

Days

of Disability

during

the 4-Week

Period

Total days of disability, irrespective of the number of persons whose disability contributed to that total, gives a clearer picture of the total volume of disability in the population than does the distribution of individuals according to the duration of their disability. The total days of disability from all conditions, acute and chronic, during the 4-week period averaged one day per person. The patterns of distribution by age, sex, and color (Table 95) were similar to those shown earlier for number of persons disabled for one or more days and disabled for various durations. The number of days of disability per 100 persons during the 4-week period was higher for females (112) than for males (76), and higher for whites (101) than for nonwhites (78). The rate was lowest (50) for persons aged 15 to 24, was much higher for children, particularly those under 5 years of age (93), and increased with advancing age to 368 days of disability per 100 persons aged 75 and over during the 4

275

HOUSEHOLD INTERVIEW REPORTS TABLE 95.

Total days of disability during 4 weeks preceding interview, expressed as a rate per 100 persons interviewed, by age, sex, and color Sex

Age

Total

All ages1 Under 5 5-14 15-24 25-34 35-44 45-54 55-64 65-74 75 and over 1

94.9 93.1 72.5 50.4 57.9 79.3 111.5 117.3 235.2 368.1

Color

Male

Female

White

Nonwhite

75.9 84.8 75.8 32.8 41.8 50.3 93.0 89.3 210.4 292.0

111.9 102.1 68.9 63.1 72.0 106.9 129.4 141.8 252.5 407.1

101.3 110.2 87.4 47.6 60.9 78.2 116.0 109.0 233.8 351.6

77.8 63.8 39.7 57.1 51.2 82.4 96.4 152.0 242.6 484.4

Includes persons whose age was unknown.

weeks preceding the interview (Figure 9). This rate may be expressed as 4 days of disability out of 28 days, or 13 per cent of all days, for persons aged 75 and over. The number of days of disability per 100 persons was higher for females than for males in every age group except ages 5 to 14, where the number was slightly higher for males. Although the rate for white persons of all ages combined exceeded the rate for nonwhites, the reverse was true for several age groups, mostly in the older ages. Total days of disability per 100 persons during the 4-week period were about twice as great among persons in the lowest income group as FIGURE 9. Average number of days of disability per person during 4 weeks preceding interview, by age 4

in >. ra •o

Bed days

3

1

Other days



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65-

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DISABILITY REPORTS

276 TABLE

96.

Total days of disability during 4 weeks preceding interview, expressed as a rate per 100 persons interviewed, by age and annual family income

Age 1

All ages Under 15 15-34 35-64 65 and over 1

All incomes

Under $2,000

$2,000$3,999

$4,000$5,999

94.9 80.4 54.7 99.5 274.5

170.6 108.4 87.8 211.6 294.2

72.2 66.1 42.2 86.7 202.9

81.3 80.6 50.6 89.8 215.5

$6,000 and over

Unknown

85.8 115.3 64.5 61.0 244.5

105.1 61.7 54.3 97.3 370.5

Includes persons whose age was unknown.

in each of the higher income groups. For children under 15, the number of days of disability was higher in the top income group, however, than in the lowest income group (Table 96). Days of disability per 100 persons varied less among income groups for aged persons than for younger persons, suggesting that age is a more important factor in the amount of disability than is income. Days Kept

in Bed during the Past 4

Weeks

Of the more than 1 out of 10 persons (11 per cent) who were disabled one day or more during the 4 weeks preceding the interview, about half (6 per cent) were kept in bed one day or more during that period (Table 97). Substantially more women (7 per cent) than men (5 per cent) had a day or more of bed-disability. The percentage for women exceeded the percentage for men for each age group beginning with 15 years of age, but it was a little smaller at younger ages. The difference was 2 (or more) to 1 for each age group between 15 and 64.

TABLE

1

97.

Persons kept in bed one or more days during 4 weeks preceding interview, expressed as a percentage of all persons interviewed, by age and sex Age

Both sexes

Male

Female

All ages1 Under 5 5-14 15-24 25-34 35-44 45-54 55-64 65-74 75 and over

6.0 5.7 7.3 5.2 5.5 5.6 5.6 5.7 7.8 9.3

4.5 6.2 7.7 2.2 2.5 3.1 4.0 3.7 6.8 5.7

7.4 5.1 6.9 7.3 8.2 8.0 7.2 7.4 8.6 11.2

Includes persons whose age was unknown.

HOUSEHOLD INTERVIEW REPORTS TABLE

98.

277

Persons kept in bed one or more days during 4 weeks preceding interview, expressed as a percentage of all persons interviewed, by age and annual family income Age

All incomes

Under $2,000

All ages1 6.0 8.5 Under 15 6.7 8.7 15-34 5.4 7.9 35-64 5.6 8.6 65 and over 8.3 8.9 1 Includes persons whose age was unknown.

$2,000$3,999

$4,000$5,999

$6,000 and over

Unknown

5.1 6.0 4.1 4.9 8.0

6.1 7.3 5.1 5.7 7.8

6.7 8.9 6.9 5.3 8.2

5.0 3.4 5.3 5.0 8.0

The percentage of persons kept in bed one or more days during the 4-week period is shown by age and annual family income in Table 98. It was highest for persons in the under $2,000 class; it was lowest in the next class and increased for the two higher classes. Among aged persons, however, there was little difference among the income groups, and the differences for children under 15 were small. Consistently low percentages of persons aged 35 to 64 with family incomes of $2,000 or more had one or more days of bed-disability during the 4-week period. Also, the age group 15 to 34 in the three higher income classes had relatively low percentages of persons with any bed-disability. Disability severe enough to keep a patient in bed for a prolonged period of time probably has a much greater impact on the lives of the patient and his family and on the community than does disability which only keeps the patient from his usual activities. This fact highlights the finding that 13 per 1,000 persons were kept in bed more than one week out of the preceding 4. The rate was 9 for males and 16 for females. It increased steadily with age, from about 6 per 1,000 persons under age 15 to about 39 per 1,000 aged 65 or older. These rates are shown in Table 99, which also gives the proportions of persons in each age, sex, and family income group who were kept in bed various lengths of time during the 4 weeks preceding the interview. Six persons per 1,000 were kept in bed through nearly the entire 4week period; this proportion was much larger for elderly than for younger persons. The increase with age was irregular because very small numbers of persons were involved. About twice as many women (8 per 1,000) as men (4 per 1,000) were kept in bed nearly all of the 4 weeks. As with total days of disability, the outstanding fact about the relationship of bed-disability to income was the very large proportion (13 per 1,000) of the lowest income group who were kept in bed almost all of the 4-week period. The earlier noted tendency to report in terms of weeks rather

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SCREENING CLINIC—METHODOLOGY TABLE D - 9 .

459

Results of symptom screening for heart disease, by color and by sex of persons screened White

results Total number of persons screened

Total1

Both sexes

Male

1,898

1,485

705

Nonwhite

780

Both sexes

Male

396

162

234

Rate per 1,000 persons screened Total Negative One question positive Both questions positive 1

1,000 791

1,000 803

1,000 826

1,000 783

1,000 750

1,000 815

1,000 705

149

141

133

149

177

148

197

60

55

41

68

73

37

98

Includes persons whose color and sex were unknown.

age groups consistently had a higher proportion of positive answers to both questions than did men of the same age group. There was no significant difference by color among the men; but nonwhite women gave positive answers to both questions more often than did white women. As in the case of the chest x-ray and the EKG, the proportion of positive screenees who sought diagnostic examination increased, in general, with age. Just under one third of the confirmed cases were reported as previously unknown to the family physicians. Comparison of the three tests. The screening procedures for heart disease resulted in the discovery of 33 confirmed cases per 1,000 screenees. The electrocardiogram was positive in 21 of these cases, and was the only positive test in at least 8 of the cases. It was more sensitive than the chest x-ray or the questionnaire, which were positive in 16 and 9 of the cases, respectively. Although the electrocardiogram produced the greatest yield of the three tests, this cannot be used as the main criterion for judging its value. The cases discovered by the EKG may or may not be less responsive to treatment than the cases found by the other methods. The 70 mm. chest x-ray also appeared useful as a method of screening for previously unknown heart disease; but here, also, it is not known to what extent these cases benefit by their early discovery. Information is not at present available as to what proportion of cases would have been missed if the questionnaire had not been used, but it is likely that this number is quite small. When an EKG and chest x-ray are being used, it seems doubtful that the questionnaire significantly increases the yield of cases. In the absence of the other two tests, however,

460

APPENDIX D

the questionnaire is sufficiently specific to be of value in detecting a small proportion of cases. Tests for Diabetes Mellitus Screening programs offer considerable promise in the control of diabetes. The fundamental cause or causes of this condition remain obscure and, for the present at least, the prevention of diabetes is beyond reach. On the other hand, there are tests which can be applied rapidly, simply, and inexpensively, and which are quite effective in early detection. Probably the preponderance of medical opinion is that, with early diagnosis, the disease can be controlled and complications largely prevented by systematic treatment employing insulin, dietary control, and other measures. The combination of availability of ( 1 ) effective tests for detection of a particular disease, and (2) effective methods of treatment contribute to the usefulness of screening for that particular disease. Joslin has defined diabetes as "an hereditary disease, characterized by an increase of glucose in the blood and the excretion of this sugar in the urine; it is dependent upon the deficient formation or diminished effectiveness of insulin secreted by the beta cells of the islands of Langerhans of the pancreas and is functionally interrelated with conditions arising in the liver and in endocrine glands other than the pancreas, particularly the pituitary but also the adrenal and the thyroid." 23 Early detection of diabetes takes advantage of the increased sugar content of the blood and urine and the relative ease with which this increase can be measured by laboratory tests. Because of the great importance of diabetes in a screening program, and because the Baltimore study used a different approach to its detection from that customarily employed, this phase of the screening program will be discussed in some detail. Value of early detection and treatment. A pathologic change, termed hydropic degeneration, in the beta cells of the islets of Langerhans is found frequently, but not invariably, at autopsy of cases of diabetes mellitus. Animal experiments have shown that control of the diabetes prevents this progressive change in the cells, and that cells which already show this change can be rescued by controlling diabetes with insulin and diet. Lukens et al.2i believe that the hyperglycemia is responsible for the M Joslin, Elliot P., M.D., Root, Howard F., M.D., White, Priscilla, M.D., and Marble, Alexander, M.D. The Treatment of Diabetes Mellitus (9th edition), p. 251. Philadelphia, Lea & Febiger, 1952. 24 Lukens, F. D. W„ Dohan, F. C., and Wolcott, M. W. "Pituitary Diabetes in the Cat: Recovery Following Phlorhizin Treatment." Endocrinology 32:475—487, 1943.

SCREENING CLINIC—METHODOLOGY

461

25

degenerative changes in the islets. Allen holds that the results of animal studies are comparable with the progressive worsening of the human case of diabetes which frequently occurs when the disease is uncontrolled. He states that diabetes progresses as long as the blood sugar value remains high, even without glycosuria. The treatment of diabetes begins, at present, too late to expect restoration of the pancreatic islet functions, states Wilder.26 He believes that treatment is most effective when instituted at the very onset of the disease. The cardiovascular-renal complications of diabetes show a definite correlation with the duration of the disease, but are less well correlated with its lack of control. Dunlop's studies in Edinburgh 27 suggest—although the evidence is not conclusive—that the aggressive treatment of the disorder over the years is a most important factor in the prevention or postponement of these complications. The occasional finding that the degenerative changes are already present when diabetes is first discovered28 suggests that a long presymptomatic period of hyperglycemia may be the cause of the complications in persons under strict control. Until follow-up studies have been made on diabetics found in the early stage by detection clinics, this possibility cannot be confirmed or denied. The prediabetic state. The potential diabetic has been described by Joslin28 as a person whose glycosuria is closely related to diet, who easily becomes sugar-free with slight dietary restrictions, and whose blood sugar values are slightly below the arbitrary values set for the diagnosis of diabetes. There is no evidence at present that the potential diabetic will inevitably develop, or even that he is likely to develop, diabetes. Indeed, there is no general agreement that such a prediabetic state exists. However, Jackson 30 goes so far as to suggest that in the prediabetic state the disorder which will eventually lead to hyperglycemia is already making itself known. Indeed, he feels that the condition should also be called "diabetes," on the basis that the diabetes is already there, with its vascular changes and other possible complications. 25 Allen, Frederick M., M.D., in foreword to Duncan, Garfield G., M.D. Diabetes Mellitus. Philadelphia, Saunders, 1951. 26 Wilder, Russell M., M.D. "The Unknown Diabetic and How to Recognize

Him." Journal !7

British Medical 28

of the American

Medical

Association

138:351, October 2, 1948.

Dunlop, D. M., M.D. "Are Diabetic Degenerative Complications Preventable?" Journal,

p. 383, August 14, 1954.

Ditzel, Jörn, M.D. "Morphologic and Hemodynamic Changes in the Smaller Blood Vessels in Diabetes Mellitus." New England Journal of Medicine 250:541546, April 1, 1954. "" Joslin et al. Op. cit. ""Jackson, W. P. U., M.D. "A Concept of Diabetes." Lancet 2:625-631, September 24, 1955.

462

APPENDIX D

Glycosuria without hyperglycemia. When glycosuria occurs in the presence of normal blood glucose levels, the condition is termed low renal threshold glycosuria. Joslin has stated that 10 per cent of such cases, in his experience, eventually become true diabetics. This statement is frequently quoted by other clinicians, but no extensive follow-up studies appear to have been carried out to support it. No theoretical reason has ever been given to explain why a person with a low renal threshold should develop diabetes. While glycosuria is common to both conditions, their suggested etiologies are not related. No treatment is advocated for low renal threshold glycosuria. Until there is more definite evidence that persons with this condition should be followed as potential diabetics, there is no valid reason why diabetes detection clinics should refer them to the family physician. Hyperglycemia in the elderly. Joslin81 mentions that a raised blood sugar level without glycosuria, owing to a high renal threshold, is more common in older persons and does not warrant the diagnosis of diabetes. Glucose tolerance tests carried out on elderly subjects show a delayed peak and prolongation of the curve, frequently accompanied by a high renal threshold. It appears advisable to use slightly higher screening levels for persons over 60 in diabetes detection clinics to avoid the referral of too many false positives. Diabetes and obesity. Obesity has a deleterious effect on carbohydrate metabolism and appears to impair glucose tolerance even in nondiabetics. The longer the duration of the obesity, the greater is this impairment.32 There is general agreement on this association, which has been confirmed by a number of studies. Contradictory opinions are held, however, on the success of weight reduction in improving the status of obese diabetics. The familial tendency to diabetes is well established. The possibility that obesity may make manifest a latent diabetic tendency would suggest that weight control is more important than usual in persons closely related to diabetics. Wilkerson et al.33 recommend that any communitywide diabetes detection program should include special appeals to such persons. " Joslin et al. Op. cit. ™ Wolfson, William Q., M.D. "Abnormalities of Body Weight." In Glandular Physiology and Therapy (5th edition), p. 442. Philadelphia, Lippincott, 1954. (Prepared under the auspices of the Council on Pharmacy and Chemistry of the American Medical Association.) " Wilkerson, Hugh L. C., M.D., Cohen, Alan S., M.D., and Kenadjian, A. B. "Screening for Diabetes." Journal of Chronic Diseases 2:464-476, October 1955.

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Advantage of true glucose values. The most commonly used of all blood sugar level estimation tests is the Folin-Wu method and its modifications. This procedure measures the total reducing substances in the blood—glucose plus variable amounts of glutathione, fructose, cysteine, ergothionine, creatinine, and other undetermined materials. Although these materials were believed to give a fairly constant figure of 20-30 mg. per cent, there is evidence that they may vary from 1 mg. per cent to over 70 mg. per cent and that they may not be constant even in the same person from hour to hour. It therefore seems possible that large amounts of these substances will cause nondiabetic persons tested by the Folin-Wu method to have blood sugar values within the diabetic range. The specificity of the blood glucose screening test can be improved by using a procedure which does not measure non-glucose-reducing substances. One of these true glucose tests is the Wilkerson-Heftmann test, which was used in the Baltimore clinic. Problems in diagnosing diabetes. There are several points on which leading clinicians do not agree in the diagnosis of diabetes. Joslin34 believes that glycosuria must be present, but not necessarily persistent, for the diagnosis to be made. This theory was followed in the Baltimore clinic, where all screenees referred as "possible diabetics" were required to have glycosuria in addition to positive blood sugar tests. It was felt that even intermittent glycosuria was likely to show up following the ingestion of 50 gm. of glucose on arrival at the clinic. In retrospect, it appears likely that this decision was not wise, and may have caused several diabetics with high renal thresholds to be missed because of negative urine sugar tests. Duncan 35 and Wilkerson et al.ie believe that glycosuria need not be present for a diagnosis of diabetes to be made. Leading clinicians again differ on the blood glucose values which are diagnostic of diabetes. This increases the problem of determining the most suitable value to use in screening for this condition. Bondy37 has commented that "the diagnosis of diabetes cannot be discarded until a normal glucose tolerance test has been obtained, nor can it be considered established unless either a considerably elevated fasting blood glucose value or an abnormal response to the glucose tolerance test has been found." " Joslin et al. Op. cit. Duncan, Garfield G. Diabetes Mellitus. Philadelphia, Saunders, 1951. " Wilkerson et al. Op. cit. " Bondy, Philip K., M.D. In The Year Book of Medicine ( 1954-1955 Year Book Series). Chicago, Year Book Publishers, 1955. 35

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However, personal physicians to whom positive screenees are referred do not usually carry out such recommendations. McLoughlin et al,38 found that of 443 screenees whose physicians believed them to be free from disease, only 6 had been given glucose tolerance tests and 162 fasting blood sugar tests. The remaining 275 had been ruled out on the basis of normal urinalyses and "clinical judgment." It would appear that many physicians are either not aware of, or do not agree with, Joslin's statement 39 that diabetes can be present in the absence of symptoms and clinical signs. A similarly inadequate diagnostic examination has also been shown to occur frequently when positive screenees were referred in Washington, D.C. 40 Fasting blood glucose values. Blood glucose levels of 130 mg. per cent (by the Folin-Wu method) or 110 mg. per cent (by the true glucose method) are frequently regarded as diagnostic of diabetes in individuals who have not eaten for 12 or more hours. However, many mild diabetics have normal fasting values, and would be missed by this screening procedure. Postprandial blood glucose values. The rise in blood sugar level which occurs after eating is greater in diabetics than in nondiabetics. There is evidence to suggest41· 42 that it is wise to use higher screening levels for those who have eaten within 2 hours than for those who have not eaten for 2 hours or more. Wilkerson et al.*3 suggest that screening more than 2 hours after eating gives less satisfactory results. It seems reasonable to believe that the variation in quantity and quality of food eaten and the unreliability of the time stated to have elapsed since eating will result in a considerable overlap in the postprandial blood glucose values of diabetic and nondiabetic persons. No matter what screening level is chosen, some reduction in sensitivity and specificity of the procedure is likely. 88 McLoughlin, Christopher J., M.D., Petrie, Lester M., M.D., and Hodgins, Thomas E., M.D. "Diagnostic Significance of Blood Sugar Findings." Journal of the American Medical Association 153:182-184, September 19, 1953. 89 Joslin et al. Op. cit. 10 Loube, Samuel D., M.D., and Alpert, Louis K., M.D. "Evaluation of Screening Procedures in a Diabetic Detection Drive." Diabetes 3:274-278, July-August 1954. " Wilkerson et al. Op. cit. *2 Kenny, A. J., M.D., and Chute, A. L., M.D. "Diabetes in Two Ontario Communities." Diabetes 2:187-193, May-June 1953. " Wilkerson el al. Op. cit.

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Blood glucose values after sugar ingestion. The most frequently used of the reliable diagnostic tests is the oral glucose tolerance test. There is considerable evidence 44 · 45 that whether 50 or 100 gm. of glucose is used, the height of the peak and the duration of the tolerance curve are closely similar. The 100 gm. dose is unpleasantly sweet to some persons, sometimes producing nausea or diarrhea. It appears, therefore, that the smaller amount of 50 gm. will be just as satisfactory in screening for diabetes, and will be more acceptable to the screenees. The effect of a dose of glucose taken soon after food has not been well studied. It is likely, however, that the presence of food will slow down the absorption of glucose, with little or no increase in the postprandial blood glucose values. Ingestion of this glucose 2 or 3 hours after eating will produce a higher rise in blood glucose values, since the absorption will be less delayed by food which has already left the stomach. It would therefore seem likely that an additional dose of glucose given soon after eating would not unduly raise the blood sugar values of normal screenees, but would sufficiently elevate the values in diabetic patients who had eaten previously that they would be above the screening level. For this reason, 50 gm. of glucose was routinely given to each screenee on arrival at the Baltimore clinic. The glucose drink. To prevent the need for weighing out the glucose and making up individual drinks, the help of a flavoring company and of a carbonated beverage manufacturer was enlisted to produce a bottled carbonated drink which required no further preparation. An orange flavoring agent, with a certain amount of citric acid, was used to overcome the sweet taste of the glucose. The method of manufacturing the drink was approximately as follows: The orange flavor with citric acid, the powdered glucose, and a 25 per cent solution of sodium benzoate were mixed and heated to produce a syrup. The quantities used were such that 2 ounces of the syrup contained 50 gm. of glucose, and that the sodium benzoate produced a one twentieth of 1 per cent solution in the final drink. Two ounces of the syrup were mechanically dropped into a 7-ounce bottle, to which 5 ounces of mildly carbonated water were added. A small number of- samples of the final drink were taken at random "Gray, Horace, M.D. "Blood Sugar Standards, Part 1, Normal and Diabetic Persons." Archives of Internal Medicine 31:241-258, February 1923. " Mosenthal, Herman O., M.D., and Barry, Eileen. "Criteria for and Interpretation of Normal Glucose Tolerance Tests." Annals of Internal Medicine 33:1175, 1950.

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during the bottling process and tested for glucose content. The tested samples were found to have a median glucose content of 48 gm. with an average error of 2 gm., or 4 per cent, around this value. The total cost of the drink, when delivered by the manufacturer, was 5.9 cents per bottle, provided the empty bottle was returned. The proportion of screenees who refused the drink, either because of its sweetness or its carbonation, was less than 1 per cent. Wilkerson-Heftmann blood glucose test. This is a modification of a true glucose method devised by Hagedorn and his coworkers. The reagents are available in the form of tablets which restrict the choice of screening levels to three values—130,160, and 180 mg. per cent. While the pipetting of the blood specimen has to be done by a technician, the addition of the reagent tablets and the heating of the constituents can be carried out automatically by the Hewson Clinitron. The screening test result is available 5 minutes after the tube containing the pipetted blood specimen is placed in the machine. The Clinitron has a maximum capacity of 120 estimations per hour. With this rate, however, additional help is needed to assist the technician in pipetting the blood, cleaning test tubes and pipettes, and reading and recording the results. It was found in the Baltimore clinic that, after one day's experience, a previously untrained person could comfortably carry out 25 estimations per hour. False positive results can apparently be caused by inadequate heating of the test tube with incomplete removal of the blood protein, failure of one or more of the reagent tablets to drop in, or inadequate cooling of the test tube at the end of the test. Every positive blood specimen was routinely retested in the Baltimore clinic to detect these accidental false positives. The rapidity of the test and its great saving in labor appear to be the main advantages of the Wilkerson-Heftmann procedure in screening. Urine sugar versus blood sugar tests in screening. Urine sugar tests have the advantage that mass application is possible—using the Dreypak technique, for instance—without the need for numbers of trained technicians. However, since high and low renal thresholds will result in false negative and false positive results, respectively, it is to be expected that this method will be less sensitive and less specific than blood sugar screening tests. A considerable number of studies confirm the superiority of the blood

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sugar tests. In at least two programs, however, the urine and blood sugar tests appeared to give equally satisfactory results. 46 · 47 Self-testing programs. Several programs have been held in which the screenee carried out his own urine sugar test at home. A number of barriers occur, however, to prevent the successful completion of the chain of events between the screenee's collecting the testing kit and his seeking medical advice because the test was positive.48 An example of these pitfalls is given by the Gloucester, Massachusetts program. 49 Forty per cent of those who collected the free self-testing kit failed to carry out the test. Of those whose initial test was positive, 50 per cent did not carry out the recommended repeat test. Seventy-six per cent of those with two positive tests failed to seek medical advice. It therefore seems possible that although a self-testing procedure may be applied to large numbers of persons, it may yield a smaller number of newly discovered diabetics than a blood-testing program screening much smaller numbers of persons. Moreover, the large number of false positives, due to the poor specificity of the urine test, may cause diabetes detection programs to fall into disrepute. Procedure in the Baltimore clinic. After ingestion of glucose, diabetic persons have blood sugar values higher than normal after 1 and 2 hours. A small proportion of nondiabetic individuals have elevated 1-hour values but normal 2-hour values. This is the basis of the procedure used in the Baltimore clinic. On arrival at the clinic the screenee was given the carbonated orange drink containing 50 gm. of glucose. The urine sugar test was carried out 30 to 50 minutes later, with 1-plus or more by the Clinitest method being regarded as positive. The blood glucose level was estimated 45 to 75 minutes after the screenee had taken the drink. Venous blood was used, screened at 160 mg. per cent by the Wilkerson-Heftmann method using the Clinitron. When the sugar content of this blood specimen was above 160 mg. per cent, the screenee was asked to remain to have a 2-hour specimen taken and screened at 130 mg. per cent. " A Summary of Some Diabetes Screening Projects. U.S. Public Health Service, Division of Chronic Disease and Tuberculosis, 1953, pp. 4-5. " Weinerman et al. Op. cit. a Getting, Vlado Α., M.D., Root, Howard F., M.D., Wilkerson, Hugh L. C., M.D., Lombard, Herbert L., M.D., and Cass, Victoria M., M.D. "Evaluation of a Method of Self-Testing for Diabetes." Diabetes 1:194-200, May-June, 1952. "Ibid.

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A small number returned at a later date to have the 2-hour test carried out; a few were unable to have the 2-hour value taken at any time. Those individuals with glycosuria, but with blood glucose levels below 160 mg. per cent at abôut 1 hour, were not retested but were considered to have a low renal threshold. Screenees with glycosuria and elevated 1- and 2-hour blood sugar values were told that they were probable diabetics and were referred to their family physicians. Those without glycosuria but with elevated 1- and 2-hour blood glucose values were advised to visit their physicians in order that diabetes could be more definitely confirmed or excluded. Screenees with glycosuria but with blood sugar values below the screening level at either 1 or 2 hours, were told that they did not appear to have diabetes, and the results of the tests were explained to them. A few, especially those who were obese, went on to their family physicians for advice on whether any precautionary measures were indicated. Results of the Baltimore clinic. Table D-10 shows the results of the blood sugar screening procedure only. Seventeen screenees had both positive 1- and 2-hour blood sugar tests. An additional 16 screenees on whom 2-hour values were not obtained, had positive 1-hour blood sugar tests. Of these 33 screenees, only those who also had glycosuria were referred as probable diabetics. Of those screenees with positive 1-hour values who were retested, 39 per cent had positive 2-hour values. The number of positives was therefore reduced by two thirds by this retesting procedure. It is likely that most, if not all, of the true positives are among those positive at 2 hours. (No diagnostic examination was carried out, however, on screenees with positive 1-hour and negative 2-hour results to determine if some diabetics were being lost by the retesting procedure.) Of the 54 screenees with glycosuria, 15 (28 per cent) had positive blood sugar values. This is shown in Table D - l 1, which appears to confirm the belief that the urine sugar test alone produces a considerable proportion of false positives in screening for diabetes. Fourteen of the 33 screenees classified as positive by the blood sugar tests were referred as probable diabetics because they had glycosuria and were previously unaware of the condition. The remaining 19 were advised, but not urged, to visit their personal physicians. Follow-up reports were not obtained on this latter group. Of the 9 screenees on whom the follow-up was completed, 5 were confirmed as having diabetes and 4 cases were previously unknown to the family physician.

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