DATA EVALUATION AND METHODS RESEARCH

Series 2

Number 17

Conceptual Problems

in Developing an

Index of Health

Consideration of essential characteristics of an index

using measures indicative of changing health status

in the United States population, with review of previous studies of general health indexes. Problems in

deciding what to measure are discussed and a method

of measurement is proposed.

DHEW Publication No. (HRA) 76-1017

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE

Public Health Service

Health Resources Administration

National Center tor Health Statistics

Rockville,- Maryland
,.

.

Vital. and -Health Statistics-Series 2-No. 17

First issued in the Public Health Service Publication Series No. 1000, May 1966

.
NATIONAL CENTER FOR HEALTH STATISTICS

DOROTHY P. RICE, Director

ROBERT A. ISRAEL, Deputy Director

JACOB J. FELDMAN, Ph.D., Associate Director for Analysis

GAIL F. FISHER, Associate Director for the Cooperative Health Statistics System

ELIJAH L. WHITE, Associate Director for Data Systems

GEORGE P. FAILLA, Associate Director for Management

PETER L. HURLEY, Associate Director for Operations

JAMES M. ROBEY, Ph.D., Associate Director for Program Development

ALICE HAYWOOD, Information Officer
CONTENTS

Page

htitiuction ----------------------------------------------------------

Previous Studies ofGeneral Health kdexes ------------------------------

Developments Influencing Health Measurement -------------------------

Attempts to Define and Measure aNation’s He~th ---------------------

Two Proposals for aGeneral Health Index ----------------------------

The Situation tobe Measured ------------------------------------------

Purpose and Conditions of Measurement ------------------------------

Conceptions of Health Levels ------- ------- ------- -------------------

Measurementof MorbidiW -------------------------------------------

AGenewal Concept of Morbidity in Terms ofDisability---- --------------

PotentialSources of DaM--------------------------------------------

ReliabUi~md Vali&w ----------------------------------------------

Conclusion -----------------------------------------------------------

References --------------- ------- ------- ------- -------------- ------- --

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12

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IN THIS REPORT the pvoblem of measuri~ levels of health is discussed

with a view to identifying measures indicative of chunging health status

in the United States population. Traditionally, mortality Yates have been

used for this pwpose but changing health pvoblems and progyams have

impai~ed theiy utility as a measure of the needfor and adequacy of health

pyograms. If new indexes aye to be devised the question of what to meas -

uye must be Yesolved.

Two essential chayacteyistics of an index of health status aye identified.

It must: (1) be sensitive to the need foy and adequacy of health activities;

and (2) be composed of measurable components. SeveYal concepts of a

population’s level of health aye examined in view of these YequiYements.

A measuye of health in teyms of moytality and moybidity seems appYopyiate. This YequiYes an operational definition of morbidity. Examination

of vayious methods of defining and measuving moybidity suggests that

formulation of a concept of the total impact of illness m@ht seyve this

puypose. The impact of illness is defined in teyms offoyms of disability

which might be mea.swed by cyoss-sectional swweys. Sowces of data,

pyoblems of Reliability and validity, and the use of such a measuve in construction of an index aye discussed.

This YepoYt is pyesented in the hope that discussion will delineate the

pyoblems involved and assist in theiy solution.

SYMBOLS

Data notavailable ----------------------- ---

Category non applicable ------------------ . . .

Quantity zero -------------------------- -

Quantity more than O but less than 0.05---- 0.0

Figure does not meet standards of

reliability orprecision -----------------

*
CONCEPTUAL PROBLEMS IN DEVELOPING AN

INDEX OF HEALTH

Daniel l?. Sullivan, Oj’ice of Health Statistics Analysis

INTRODUCTION

A population is generally considered to have a

level of health which rises or falls over time and

can be compared to that of other populations.

Health is positively valued in our society and improved health status is an accepted goal of communities and the nation. Public health programs

invoke this notion to compete with each other and

with other government activities for budget allocations. Both administrators and legislators attempt to allccate resources ‘and evaluate health

programs by considering their contribution to the

overall health of the population. An index of health

status is a specific measure of selected health

characteristics which purports to be useful in such

assessments. Since the notion of health levels is

a difficult one to define precisely, and a realistic

index must select and summarize measures which

can be obtained, a single index cannot reflect the

full range of meanings associated with the idea of

health levels. It can only approximate the idea and

attempt to reduce the assessment of health activities to a rational and empirical formula.

Indexes based on mortality, such as crude and

age-adjusted death rates, infant mortality rates,

and the expectation of life, have traditionally been

used as measures of levels of health. Control of

mortality has always been a paramount goal of

health activities and variations in death rates are

a direct measure of progress toward that goal.

The assumption is often made that changing mortality reflects changes in other aspects of health

as well. Recently, however, crude and age-adjusted death rates for the U.S. population have

shown little change after a long period of decline

over the years 1900-1954.1 Moriyama has analyzed the mortality patterns involved in this

change of trend. He concludes that mortality

from chronic diseases and accidents is likely

to sustain the death rate near its present level

until major advances are made in the control

of deaths from these causes. The same analysis

shows that patterns of age-cause specific mortality are shifting but producing little net change.

Stability of the death rate would not imply no

change in health status. It would merel y emphasize

a difficulty inherent in the use of mortality statistics as measures of health status. They tell

little about the living, while the health of the living

has become a very important aspect of health

status. As mortality has declined the scope of

public and private health services has increased

and new objectives have been established. The

economic and social consequences of illness now

receive more attention than formerly in evaluating

levels of health and the importance of health problems. The chronic diseases have become relatively more important. Their consequences include not only death but reduced productivity, prolonged disability, and the need for care.

These considerations suggested that a more

sensitive and informative measure of levels of

health might be obtained with an index based on

health characteristics of the living as well as

mortality. To proceed further it was necessary

to specify the comparisons to be made with such

an index. The availability and relative compa1
rability of mortality statistics make them a feasible basis for comparisons between nations, between areas within nations, and between successive years for the same population. As yet, the

classification systems and procedures used to

measure other health characteristics are much

less uniform, and no one index based upon them

is likely to be as versatile. Constructing a health

index for the specific purpose ofmeasuringtrends

in the health level of the U.S. population was chosen

as the limited objective for examination here.

An index for this purpose should fulfill two

requirements:

(1) It shcwld show changes over time in

significant aspects of the health of the

living as well as in mortality.

(2) It should be subject to analysis into

components which provide a useful description of hpalth problems underlying

index values.

Construction of such an index requires selection

of the concepts to be measured, specification of

operational definitions for these concepts, and determination of the measures to be used and a

method of combining them into a single index.

Death is a well-defined event and the major problems associated with mortality indexes are those

encountered at the final stage—problems involving

the accuracy and adequacy of data and methods

of summarization. To measure other aspects of

health the most difficult problem is to determine

what can and should be measured. The meaning

of health is not a matter of universal agreement.

A discrepancy exists between many frequently

quoted goals of health programs and the operational criteria and procedures now feasible in

measuring health characteristics of large populations. This report does not propose a method

of constructing an index, but attempts to delineate problems and formulate a measurable concept of health which might be taken as the basis

of the index desired.

PREVIOUS STUDIES OF GENERAL

HEALTH IND,EXES

Reexamination of existing indexes of health

has been influenced by other developments coinciding with the decline of mortalit y from infectious

diseases. Among these are increased emphasis on

prevention within medicine, technical improvement in survey techniques for the measurement

of population characteristics, and growing awareness of certain difficulties in the definition and

measurement of chronic diseases. These have

been recurrent issues in recent studies of health

measurement.

Developments Influencing Health

Measurement

Renewed awareness that social factors influence the occurrence of disease and illness and

emerging interest in the use of medical knowledge

to prevent disease and improve normal functioning

have produced an orientation within English and

American medicine often designated as social

medicine. Associated with social medicine is the

goal of promoting positive health—a goal reflected in the World ‘Health Organization definition of health: 2

Health is a state of complete physical, mental

and social well being and not merely the

absence of disease and illness.

Positive health has been defined in various ways

but the concept generally implies existence of

identifiable levels of health among those free of

apparent morbidity. 3-10 From this point of view

morbidity and mortality statistics are inadequate

in that they measure the negative complement of

health rather than the degree to which optimum

health is achieved in a population. 3’779’11The

possibility of measuring health status in this

sense has received attention in most recent

studies of general health indexes. lz15

Interest in health measurement has also been

stimulated by the rapid development of sample

survey techniques and their application in health

surveys. 16Sample surveys have been used to

collect national statistics on the health of the

living in several countries and the continuing

National Health Survey now includes coordinated

surveys involving different sources of health

information on the United States population. 17-24

While such surveys can provide much information

not otherwise obtainable they usually must be

designed to provide data for many needs and purposes. The concepts and definitions used in

measurement must often be modified to suit survey methods. If this source of information is to
be used for a health index, the qualities desired

in the index must be reconciled with the limitations of multipurpose surveys.

A third factor of importance in recent studies

of health measurement is the interest focused

on chronic diseases and the difficulties encountered in measuring these conditions and quantifying the problem they present. They are often

slow in onset, progress gradually, and may exist

for months or years before death occurs. During

this interval a chronic disease may be classified

according to various manifestations and measured

along many dimensions. One troublesome consequence of the time dimension is that neither incidence, prevalence, nor mortality adequately

represent the problems associated with chronic

conditions. Another is that many of those diseased

may be functioning adequately, and reveal no

signs of “sickness” or disability. The chronic

diseases also raise a question of the relation of

disease to health status. Some diseases, such as

diabetes, can be medicalIy controlled if not cured.

Others, such as arthritis, are generally not fatal,

and lowered. general mortality serves to lengthen

the lives of diseased individuals. This poses the

dilemma of prevalence of disease increasing as a

result of successful medical intervention.

For many chronic diseases diagnostic criteria are not uniform, but vary from study to

study. Measuring these conditions in a population

raises the problem of which criteria to use for

identification of cases. Any criteria chosen may

fail to suit the needs of some persons interested

in the resulting data. Where interest centers on

trends in incidence or prevalence, criteria upon

which experts can agree when the time series is

begun may become obsolete as knowledge of the

disease and techniques of detection improve. A

related measurement problem is that of identifying comparable cases of the various chronic

conditions. If a measure of the chronic disease

problem in terms of incidence or prevalence were

desired, it would be reasonable to count cases of

each disease at comparable levels of severity.

But clinical measures of severity vary with the

disease in question and no one is common to the

many chronic conditions. With the emergence of

chronic diseases as more prominent health problems these difficulties have aroused increasing

concern among investigators.

Attempts to Define and Measure

a Nation’s Health

In the United Kingdom the Survey of Sickness

was initiated during World War II as a means of

maintaining surveillance over the health status

of a population subjected to wartime conditions

of scarcity and stress. The entire Survey was referred to as a “Health Index.” 92’23’25 Its continuing operation from 1943 to 1952 represents the

first attempt to supplement mortality data by collection of annual morbidity data representative of a

national population. The Survey demonstrated the

feasibility of extending regular collection of health

information beyond mortality. Its periodic reports

were a series of statistical tables representing

various aspects of morbidity. No method of

summarizing the various types of information into

one or a few figures which provided a comprehensive measure of health status emerged from

this effort.

The relation of available health indicators to

the concept of health received more systematic

study as a result of efforts by a United Nations

Committee of Experts to recommend statistical

indicators of a nation’s level of living. The Committee identified health—including demographic

conditions-as one of 12 areas it was essential to

measure in comparisons of level of living.lg

The World Health Organization subsequently appointed a study group to recommend suitdble

indicators of a nation’s health. The scope of

their study was limited by the need to recommend

indicators based on information sources likely

to be available for a number of nations. Only

three generally accessible indicators-all measures of mortal it y—were considered sufficiently

comprehensive to receive a cautious and limited

endorsement for this purpose. These were: (1)

expectation of life at birth and at one year of age;

(2) the crude death rate; and (3) the proportional

mortality ratio. The last measure, defined as

deaths at age 50 and above as percent of all

deaths at all ages, was proposed by Swaroop and

Uemara, primarily for use where lack of adequate

information precluded use of death rates or other

measures in comparisons of health status. 26’27The

study group recognized, however, that these were

at best very limited measures and recommended

studies directed toward the development of more

3
adequate indexes in countries where more abundant data could be obtained. Health surveys were

considered a very promising means of obtaining

data suitable for comprehensive healthindicators

where they are feasible.15’28

Means of reducing the broad notionof health

to asetof measurable criteria, suchas mightbe

incorporated into a sample survey, receivedconsiderable attention from two subcommittees appointed by the U.S. National Committee on Vital

13,14 Both of these groups and Health Statistics.

took as their starting point the general ideas of

positive health or wellness and attempted to

analyze them into component areas within which

measurable indicators could be found or devised.

Neither group was able to recommend specific

operational criteria for the measurement of these

concepts, and their deliberations and recommendations are primarily valuable for revealing

the great diversity of meanings which can be

concealed by these terms.

Two Proposals for a General Health Index

Recently several authors have taken a more

pragmatic approach and proposed methods of combining mortality data with some specific indicator of the health of the living derived from

survey measurements.

A method suggested by Sanders proceeds from

recognition of the fact that improved health care

may actually increase the prevalence of disease

in a community .25Rather than measures of disease

he recommends measures of “functional adequacy”

as an indicator of the health status of the living.

These would be obtained by determining whether

the individual is capable of fulfilling the requirements of a social role appropriate to his age

and sex. The number of days each year a living

individual could fulfill his role’ might then be taken

as the measure of his health status. Rates based

on this information would be used together with

mortality rates in the creation of a modified life

table. In this table a cohort of births would be

exposed to the probability of time lost through

functional inadequacy as well as the probability

of death at each age. The outcome of such a

table is referred to by Sanders as a measure

of “effective” life years and would constitute a

measure of the current health of the population

which reflects both mortality and the effects of

morbidity. This procedure successfully avoids

the problem of interpreting measures of disease

prevalence by measuring the effects of disease

rather than the existence of disease. Since the

proposed method has not as yet been presented in

detail, it is not clear what the criteria of capacit y to fulfill a social role would be at each age,

nor how the required probabilities might be

estimated. The author suggests the criteria might

be physiological measurements of capacity, although this does not seem a necessary part of such

an approach. The idea of combining mortality and

morbidity information through some extension or

modification of life taMe procedures, however,

may be a promising direction in further efforts

at development of a single index.

Another general index of health has been proposed by Chiang. 30 This index is a weighted average of age-specific components derived from the

death rate and a measure of average duration of

illness within each age group during a year. The

index results from consideration of probabilistic

modeIs of the frequent y of illness, the duration

of illness, and the monthly distribution of mortality during a given year. The author presents

a detailed description of the models derived, but

how well they fit empirical data on illness is still

uncertain. In the models illness is assumed to be

a recognizable state of measurable duration but

how it is to be measured is not specified. It is

also assumed that the frequency and the duration

of illness are independent random variables.

Whether these assumptions can be made may

depend upon the definition of illness used for

measurement. The fit of the model needs to

be tested against data from sources using different definitions of illness before this question can

be settled.

These studies, taken together, clarify the

problem somewhat. International comparisons of

health must be limited to a few indexes, primarily mortality indexes, at present. A more

comprehensive national index of health may be

possible for the United States, but what it should

measure is still not clear. Sanders’ and Chiang’s

approaches suggest methods of using data similar

to that collected by existing sources, but neither

defines specifically the variables to be measured.
The following section will attempt to identify concepts which serve the purpose of a national heakh

index and which can be measured with existing

techniques.

THE SITUATION TO BE MEASURED

Purpose and Conditions of Measurement

Measurement of health implies some set of

procedures for classification of individuals. The

“health” of individuals is classified by very different procedures in different situations, however.

Possibly the simplest procedure is to accept the

individual’s judgment of his own state of health

as is frequently done in everyday life. A physician’s judgment based on observations, clinical

examining procedures, and evidence from laboratory tests is another procedure by which health

might be classified. Although this might seem to

be a very objective and unambiguous method

very different classifications can be built upon

physicians’ evaluations. A physician in private

practice may classify individuals as healthy if no

signs or symptoms of disease are revealed by

examination. The scope of his examination, however, may depend upon the patient’s initial complaints, the conditions he expects to find in individuals of that age and sex, and the facilities

available. An industrial physician may classify

an applicant’s health primarily with reference to

his presumed ability to meet the demands of a

particular job, and his classification might not

be influenced by conditions irrelevant to job performance. In contrast, physicians examining military recruits may have very rigorous criteria of

health and attempt to predict adjustment to

many conditions not found in civilian life.

In other situations other criteria will be

emphasized. Actuaries may use criteria selected

solely for their value in predicting specific future

occurrences such as death, an accident, or incapacity for work. In the evaluation of mental

health or mental illness, both observations and

classification criteria used may differ greatly

from those used in clinical medicine. Judgments

of mental health and illness are usually inferences

based upon behavior in interviews, test situations,

and everyday life. Another very different concept

of health is implied when measures of poverty,

crime, and vice are taken as indications of the

social health of a community. Reference to such

classifications as health classifications generally

rests upon an assumed analogy between communities and biological organisms and should not be

confused with such measures as death and morbidity rates which are community averages derived from classifications of the health of

individuals. Health classifications can be based

on many other procedures, such as those used

in health interview surveys, or observations of

growth and development in children, or classification of sanitary practices in the individual’s

environment.

It is apparent that an individual classified

as healthy by one set of criteria may be labeled

unhealthy by another. This occurs frequently when

classifications of mental health and physical

health are compared. It proves more disconcerting

when two systems of classifying physical health

produce inconsistent results. It may even be newsworthy if a star athlete is rejected for military

service because of a “minor” physical defect.

Such inconsistencies appear because an individual’s classification is meaningful only within an

implicit or explicit frame of reference. The frame

of reference of a health classification includes the

purpose, some rules for selecting and classifying

observations, and the assumption that certain

observations can be made. Systems of health

classification differ in these respects and the

meaning of health varies with these differences.

Health is often spoken of as if it were a directly

observable characteristic existing within the

individual, but measurement of health, in fact,

requires selection from many potentially measurable characteristics of a person or a population.

How the measure is to be used is one consideration

in the selection of these indicators. Another,

equally important, is the complex of circumstances surrounding the measurement prccess.

These set limits on what it is possible to observe

and measure.

Variables selected as the basis of an index

must be ones that can be measured satisfactorily

in a large population. The goals of the index imply

that the component measures of an index be representative of conditions in the entire population.

Some rich sources of health information such as

hospital and insurance company records relate
only toselected segments of thepopulation. Sample

survey methods can provide representative data

but their use requires acceptance of their technical and practical limitations. Many procedures

useful in evaluating the health of individuals’or

small groups are not well suited to survey conditions. Medical diagnostic techniques, for example, have been developed primarily for use in

clinical situations on patients strongly motivated

to cooperate. Sick individuals are willing to endure

painful, embarrassing, or burdensome examinations for the sake of recovery. Many would not

be acceptable to volunteer members of a survey

sample where they would be applied to sick and

well alike. Similarly, evaluation of health in

individuals or small groups is often carried out

in relatively favorable circumstances. If school

children, military personnel, industrial employees, or similar groups are being studied, members

may be relatively accessible for repeated observations over time. In a population geographic

mobility, the need for a sample of adequate size,

and the need for sustained cooperation combine

to make measurements based on repeated observations a much more complex and expensive

operation. If sample surveys are to be “used it

would be desirable, if possible, to base an index

on variables which can be measured from a crosssectional survey.

In evaluating variables which might be used to

construct an index of health, these two criteria

of relevance and accessibility of the necessary

data were primary considerations.

Conceptions of Health Levels

One conception of the level of health of a

population equates the notion to a measure of

environmental circumstances conducive to health.

Thus, a high ratio of physicians and nurses to

population, a large proportion immunized against

infectious disease, and provision of facilities for

detecting and referring cases ofchronic disease

to physicians would denote a high level of health.

Conversely high levels of air pollution and water

pollution, inadequate sewage facilities, or unsanitary conditions for marketing of food might

be taken as indications of a low level of health.

An index of health levels might be constructed

by setting standards in a number of these areas,

measuring the degree to which such standards

are met, and combining the measures into a single

figure. But the resulting measure would be

largely a measure of the amount of activity and

money expended to improve health rather than a

measure of the outcome of these activities. Since

it would be based upon application of existing

knowledge and techniques it would fail to show

where new knowledge is needed or new techniques

are called for. It would provide no measure of the

importance of the various components “relative”

to general goals and to each other. In fact; judgments of the prospective health effects and importance of a larger number of environmental

factors would be necessary in deciding whether

they should be used as components in the index.

Population health levels defined’ and measured in

this sense are useful in evaluating the effort and

efficiency of health agencies relative to accepted

standards. In order to evaluate the effectiveness

of such effort, however, more knowledge of what

is happening to individuals in the population is

needed.

An alternative view of health levels that has

received much attention is the idea of measurable

levels of positive health. The model of health as

a continuum extending from death to some optimum

state of well-being was apparently first used “by

Reed. 8 He carefully identified it as a heuristic

device which greatly oversimplified a situation

characterized by many possible axes of measure.

ment. This qualification has not always received

enough emphasis. Some definitions imply that

health is an underlying characteristic of individuals with some “true” measure independent of

the purpose of measurement. In fact a hea:lthy -

unhealthy dimension can be recognized in many

characteristics studied by the biological, psychological, and social sciences. It conveniently designates regions of measurement considered favorable and unfavorable, but the terminology can be

applied to concepts and variables which are

theoretically and operationally distinct. The interrelationships of these variables are likely to

be complex ones, where they exist, and must be

empirically demonstrated. There ‘is little empirical justification for the assumption that a

unidimensional continuum underlies and relates

the measures referred to as healthy and unhealthy in different contexts. Health, defined

6
without reference to a specific situation or purpose of measurement, may be merely a verbal

artifact.

Failure to designate the concrete frames of

reference within which health is to be measured

may account for the variety of meanings assigned

to positive health and the difficulties encountered

in efforts to arrive at an operational definition.

In the World Health Organization definition of

health quoted above, for example, levels of positive health embrace the broad areas of physical,

mental, and social well-being.2 Gordon, on the

other hand, suggests that positive health levels

correspond to the much more restricted notion

of levels of resistance to disease. 31 Attempts to

reduce these general notions to some practical

combination of operationally defined measures of

a population have generally led to one of two results. Some conclude that only indirect measures

of “the absence of health, ” such as measures of

morbidity and mortality, are available andpositive health is immeasurable at present. 5~11Y32Y33

Others have suggested research directed toward

development of a measurable definition.7-9’ 31’34

Neither group of studies has provided a definition

that seems useful for the present purpose.

Possibly the situation can be clarified somewhat by considering specific measurement contexts. The notion of positive health levels seems

a potentially fruitful means of study ingvariations

within groups characterized by low mortality and

infrequent serious morbidity. Freedom from

disease and illness are minimal conditions of

positive health common to many definitions and

these conditions can sometimes be approximated

in selected groups such as normal children, young

workers, and military recruits. Medical facilities

and personnel designated to serve such groups

may have the capacity to do more than treat the

cases of serious illness that arise. They can realistically set themselves more ambitious goals

such as reducing susceptibility to disease or

increasing the functional efficiency of the individual. If such goals are set, measure of progress will be needed, but these need not be

restricted by the requirement that they be capable of application to the population at large. For

large populations as they exist today, however,

disease, illness, and death are still ever-present

problems. The occurrence of these events is a

more compelling guide for allocation of resources

than variations in positive health. Moreover,

knowledge of these negative aspects of health is

more useful information in the delineation of

current health problems. Negative measures

still seem to be the most appropriate measures

where the health problems of a population are

under study.

A schema of levels of health that seems well

suited to our purpose has been proposed by a

Work Party of the American Public Health

AssKiation.s5 Although their purpose was to describe successive stages of development in public

health programs, their analysis suggests a useful

hierarchy of goals implicit in private health activities as well. They identified four stages of concern and activity which emerge in turn as public

health programs develop in an area.

(1) Mortality .—The conservation of life is

of paramount importance at this stage.

(2) Serious mo?’biditY. –The goals at this

stage are prevention, control, and treatment of

conditions that disable, cripple, or produce

chronic illness.

(3) Mino7 morbidity .—Concern is focused

here on minor illnesses and conditions that

cause inconvenience, economic loss, personal

tension, annoyance, or impaired social relations.

(4) Positive heaZth. —This stage involves

programs intended to heIp all persons attain

physical vigor, mental well-being, and constructive and wholesome relations with others in a safe

and pleasant environment that promotes longevity

and happiness.

In this schema the stages are overlapping

ones and activities at a later stage are added as

available resources increase, but do not replace

the concerns of earlier stages. The rather vague

definition of positive health implied here can safely

be overlooked, because the committee realistically judged the United States in 1960 is ready to

begin health activities at the third stage—that of

minor morbidity. While the report emphasizes

initial steps that can be taken to extend effective health work into the area of minor morbidity,

it makes it clear that mortality and serious morbidity continue to be major areas of concern.

The order of these stages reflects a hierarchy of goals that is widely used in forming

official policies, conducting medical practice, and

7
making everyday decisions in health matters.

Death and morbidity are overriding considerations

in that they seldom take second place to other

aspects of health. This clearly involves a value

judgment, but it is one widely held by persons

interested in the evaluation of health programs.

Variations in measures of death andillness might

be a widely acceptable indication of progress in

health activities amlofhealth problems demanding

attention.

An index reflecting both morbidity andmortality seemed worth pursuing but these components

needed measurable definitions. Mortality measures are generally clearly related to death, a welldefined event with adequate operational referents

for our purposes. Morbidity, however, is a diffuse and general term which requires clarification.

Measurement of Morbidity

Just as health is a general term embracing

a number of methods of classifying and measuring

individuals, morbidity can also refer to different

procedure for identifying and classifying persons

considered “sick” or “ill.” Several attempts have

been made to classify the various concepts of

morbidity which result from different definitions

and sources of information. Elinson lists six

distinct types of morbidity measures and recognizes that others may exist.~b In his evaluation of

morbidity data based on interview surveys, Feldman distinguishes five different sources of information upon which a “diagnosis” may be based.37

Most morbidity concepts seem to involve some

combination of three types of evidence, which can

be labeled for discussion as: (1) clinical evidence;

(2) subjective evidence; and (3) behavioral evidence. For the present purpose it will be sufficient to consider some of the measurement

problems posed by each class of evidence and

the suitability of such evidence for an index of

health status.

Clinical evidence consists of signs, symptoms, laboratory test results, and observations of

tissue pathology which have been evaluated by a “

physician and organized according to diagnostic

categories or syndromes. The extensive system

of diagnostic categories developed in clinical

medicine has proven a valuable tool inprognosis,

treatment, and the investigation of causes of illness. Its value has produceda tendency to think

of illness as equivalent to existence of disease

and has obscured the process of selective observation and abstraction which physicians carry

out in arriving at a diagnosis. Clinical classifications select those characteristics of thepatient

useful in treatment of his illness and may

necessarily omit other characteristics of importance to the individual himself or to society,

Conditions classified together on the basis

of clinical evidence are not uniform in their

effects upon individuals. Examination can and does

reveal diseases and abnormalities unsuspected by

the individual. Individuals can vary considerably

in their subjective and behavioral responses to the

same disease. On the other hand illness experienced by the individual or reflected in his behavior may not be subject to clinical classification

for many reasons. In some cases medical care

is not available and in others the individual may

choose self-treatment. Where a physician is consulted the signs and symptoms may be too

irregular or too transitory to permit a diagnosis

with available facilities, or they may respond to a

nonspecific treatment prior to diagnosis. How

thoroughly episodes of illness experienced by

individuals can be allocated to established categories is unknown.

Valid measures of illness based on clinical

evidence require that at some stage in the

measurement process there be an expert judgment based upon clinical observation, examination, and/or testing of the individual. This

requirement is difficult to reconcile with the

need for measures representative of the population. Most potential sources of valid cl,inical

information— such as private practitioners, clinics, hospitals, and insurance systems—relate not

to the population at large but to selected individuals and selected groups of clinical conditions.

The decision to seek medical care may be influenced by income, attitudes toward health care,

accessibility of facilities, perceived seriousness

of the complaint, or other factors. The nature and

extent of bias introduced into clinical data from a

given source is generally uncertain. Moreover the

bias associated with similar sources may depend

upon location, auspices, or policies. No feasible
method exists for correcting biases in data from

the wide variety of sources serving the U.S. population. Data from these sources are useful for the

study of conditions as they are encountered in

clinical practice, but cannot be safely taken as

measures of conditions as they occur in the population.

Conditions reported by individuals will be

clinically valid only if: (1) a valid diagnosis

occurred; (2) it was reported to the individual;

and (3) he repeated the information accurately

at the stage of data collection. Obviously such

data contains the same sources of bias inherent

in medical care sources, and, in addition, the

possibility of other biases in transmission of the

information. Reliability y and validity of clinical

classifications based on interview reports may

vary considerably with the nature and refinement

of the diagnostic categories used. 38 Whether such

data are adequate will depend upon the need for

diagnostic accuracy. Here it is sufficient to note

that reports of diagnoses are not operationally

equivalent to clinically recorded diagnoses. As

criteria of morbidity in the population they also

select in favor of medically attended conditions.

Representative measures of some clinical

observations and some clinically defined diagnostic categories have been obtained by combining

clinical examination procedures and sample survey methods .39 While this can be done successfully for some single conditions, it cannot readily

be extended to obtain meaningful clinical measures of the existence of morbidity in general. A

,survey can accommodate only a limited number of

examination procedures, and there is no apparent

means of selecting a “representative sample of

diseases” to be sought from the many diseases

recognized in clinical medicine. Diseases vary

greatly in the amount of time, observation, and

technical equipment required for accurate diagnosis. Some would require painful or embarrassing examinations conducive to a high refusal rate

among volunteer examinees. Others would strain

both the time requirements of a survey and the

patience of volunteers by requiring protracted

observation. To obtain valid clinical data on the

presence of morbidity, examination surveys must

concentrate on one nr a few conditions which have

well-defined criteria susceptible to measurement

under survey conditions. 40 Clinical medicine has

numerous diagnostic categories but no widely

accepted general criteria of morbidity which

could be readily measured by an examination

survey.

Were there fewer problems in the measurement of disease, there would still exist the problem of ambiguity in the meaning of existing

cases of disease mentioned earlier. Improved

detection of disease and improved means of controlling mortality can both serve to increase the

number of cases of disease found in a population.

An index based on the existence of disease could

penalize rather than favor these desirable activities.

These considerations suggest that a concept

of morbidity based on other sources of evidence

might be more readily measured and might

provide a better indication of the adequacy of

health programs. Health surveys have frequently

measured illness in terms of the personal and

social consequences of disease, rather than the

existence of disease. Such concepts of illness are

less familiar ones than the diagnostic categories

of clinical medicine, and, of course, would not

serve as well for the treatment of patients or for

man y epidemiologic investigations into causation.

Nevertheless they measure dimensions of illness

which are important to the individual and society

and often are not indicated by a clinical diagnosis.

Subjective evidence Of morbidity here refers

to indicants such as an individual’s report of

symptoms or feelings of illness or his opinion of

his health status. These subjective states also influence a person’s behavior and may constitute

part of the evidence a physician considers in

making a diagnosis. In some health surveys, however, the report itself has been used as a

sufficient indication of morbidity. 17,19W~341

Where this is done the resulting measure of

morbidity is very difficult to interpret.

How individuals verbalize their health status

may be an important determinant of when they

seek health care, and, therefore, a variable

deserving study in its own right. It is not clear,

however, what factors influence the expression

of verbal complaints. Two studies of older persons indicate that self-evaluations often differ

from physicians’ evaluations, but the studies disagree on the extent of the difference.%ys These

studies and others indicate that verbal state9
ments about health reflect a complex of attitudes,

situational determinants, and background factors

such as education and social status !4!~%I%emajor

determinants of verbal descriptions of health

status have yet to be identified and—more impor.

tant—may be completely irrelevant to any objective criteria of health status or the need for health

care.

Use of subjective evidence of morbidity would

require a complex and uncertain process of inference wherever measures of morbidity varied between groups or over time. The implications for

utilization of health resources would be doubtful,

at best, until the relations of verbal responses

to more objective indicators are more firmly

established.

Behavioral evidence of movbidity includes

such indications as absenteeism, restriction of

specified activities, medical expenditures, seeking medical care, or institutional confinement.

It is often not possible to observe these behavioral indications as they occur. The data

obtained, therefore, are generally based on interviews or on records maintained by the individual

or by an outside source. Definitions of morbidity

based on behavioral evidence have generally been

used, and some have been devised for the specific

purpose of avoiding the difficulties of clinical and

subjective definitions. They are better suited to

survey measurement techniques than clinical concepts, yet try to reduce the ambiguity of purely

subjective reports of health status by using public

observable events as referents, even where the

individual is the only source of information

available.

The information contained in many record

systems implies a behavioral concept of morbidity. Numerous organizations maintain records

of sickness absenteeism, utilization of medical

care, expenditures covered by insurance, disability compensation claims, or other items indicative of morbidity. These records contain

observations of behavior serving some organizational purpose and may or may not include

clinical information. They can be exploited in

many ways for health studies. They fail, however, as a source of representative data on morbidity in the population. The records frequently

relate to episodes rather than persons and may

show only that portion of an illness important

in administration. Coverage is determined by

administrative or financial policy decisions. No

one record system covers more than a segment

of the population and overlapping coverage is

common. Variation in terms and definitions and

incomplete and overlapping coverage makes combination of data from various sources an impractical means of obtaining representative national

estimates.

Behavioral measures of morbidity can also

be based upon interview reports obtained, from

representative samples of the population by health

surveys. Here morbidity is inferred from behavioral evidence but the source of information

is the individual’s report rather than a recorded

observation. Information on many behavioral indicators can be collected by interviews but some

indicators are better suited to a general concept

of morbidity than others.

Reports of medical care or medical expenses

are one basis for inferring the existence of morbidity. As with clinical data based upon medical

care sources, however, there are many selective factors at work. A concept based on care

or costs would exclude all untreated episodes

and would include some minor episodes where

the decision to seek care was primarily a result

of convenience, legal protection, or personnel

policy.

Loss of time from school or work is also

an indicator, of morbidity which can be reported

in interview surveys. These criteria apply only

to a part of the population, however, and cannot

be used for preschool children, housewives, or

retired persons, nor can they be applied to holidays and vacations. To overcome this difficulty,

general concepts of disability have been devised

which identify morbidity in terms of conditions

reported as interfering with the usual activity of

the individual or with activities commonly expected of persons within broad population groups.

These provide criteria of morbidity applicable

to varied individual situations.

Use of disability reported in interviews as

an indicator of morbidity results in a measure

of the consequences of disease and injury. Disability criteria can be stated so that medical

care is not a necessary condition and the bias

of selection associated with measurements based

on medically attended cases is avoided. They seek

10
to avoid the ambiguity of purel y subjective reports

of illness by providing the respondent with an

objective frame of reference for describing his

experiences. While a period of restricted activity

is a more objective event than a report of “feeling

ill” it also has a subjective aspect which must be

recognized. The decision to reduce his usual

activities reflects the individual’s attitude toward

illness and self-care, the expectations or demands

of his family, his employer and his associates,

his knowledge or beliefs about the symptoms

present, and other social and cultural factors.

Where interview reports accurately describe behavior they measure a complex phenomenon involving the individual’s subjective assessment of

his situation as well as physical incapacity. This

complexity is a characteristic of the phenomena

being measured, however, and not an artifact of

the method of measurement. Disability occurs in

a social setting and, like other social phenomena,

cannot be measured in isolation from the setting.

It has sccial consequences regardless of the nonmedical factors which may influence its occurrence. A condition which disables a salaried

worker may not disable a person paid on a daily

basis—this makes the disability no less real for

the salaried worker and his employer. Disability

measures reflect the impact of morbid conditions

as they influence the social participation of

members of the population, In this respect they

measure an aspect of morbidity important ig any

evaluation of the health status of a population.

Several concepts of morbidity based upon

different forms of disability reported in interviews are now being measured in samples representative of the U.S. civilian, noninstitutional

population by the Health Interview Surve y.38 Since

that Survey provides a stable source of annual

estimates applicable to a large segment of the

U.S. population, the operational definitions used

are pertinent to the problem of defining morbidity

for use in a national index of health status. This

was considered a promising source of data for a

national index if an adequate concept of morbidity

could be defined in operational terms suited to

interview survey measurement.

In our culture very general roles can be

assigned to broad population subgroups defined

in terms of age, sex, and other characteristics.

One concept of disability used in the Health Interview Survey defines such roles for four categories

of individuals: preschool children, school-age

children, housewives, and workers (including all

others). 38 Each role is defined in terms of a designated “major activity” for the group involved.

These are play, school attendance, housework, and

work or business, respectively. This schema is

now used to determine long-term disability status

only for persons reporting specified chronic

diseases or impairments. Individuals are classified by the survey respondent into one of four

categories ranging from “unable to carry on major

activity for their group” to “not limited in activities. ” It should be noted that the response is in

terms of the individual’s ability to OCcupy the

designated role, and not whether it is, in fact,

occupied at the moment. Broad social roles are

used here as a frame of reference for classifying

an individual’s usual health status relative to

social expectations.

The Health Interview Survey uses two other

methods of measuring disability which ma y be useful in forming a unitary concept of disabling morbidity)3SChronic mobility limitation is also classified for those reporting chronic conditions. This

is measured by having the respondent classify the

individual into one of four categories descriptive

of his usual degree of mobility. The categories

range from “Confined to the house” to’ ‘Notlimited

in mobility. ” T&s classification dces not depend

upon the major activity of the individual’s group.

The mobility limitation item is not used in each

year of the Survey.

The third general concept of morbidity used

is that of a day of restricted activity, which is

applied to all individuals covered by the Survey

regardless of activity or mobility limitation.

Respondents are asked to report any day during

a 2-week-recall period when the individual cut

down on his usual activities for the whole day.

This item is used in each year of the Survey and

is a basic survey criterion of short-term morbidity. Usually these three classifications are not

interrelated in survey reports since the first two

are meant to apply to persons with chronic conditions while the third is intended for measuring

current variation in health status.

Each of these survey items classifies individuals from a different viewpoint and measures

a part of the total impact of illness upon the popu11
lation. For an index of health status it would be

desirable, if possible, to obtain a unified concept

of morbidity in terms of disability. A schema of

the total impact of illness will be outlined. It is

an attempt to integrate these methods ofmeasuring disability and relate them coherently to each

other. The concept is a measurable one, although measurement will require some additional

sources of data and some modification of current

Health Interview Survey procedure.

A General Concept of Morbidity in

Terms of Disability

Consider a single day. Those disabled for

that day might be classified into the following

mutually exclusive categories:

(1)

(2)

(3)

Persons commect to reslclent mstltutlons

because of ill health. This category should

include only those unable to leave the

institution for health reasons, and exclude

residents free to come and go, prisoners

confined for punishment, well children

living in institutions, and similar individuals not disabled. Persons excluded

should be classified according to the

following categories.

Persons—not classified in (l) —with serious continuing limitation of mobility.

This might be defined to include all

persons whose mobility limitations are

classified by the respondent as “Confined to the house,” and “Cannot get

around alone. ” Its measurement would

require that the limitation of mobility

classification be used for all persons not

classified in (1) above. (See reference 38,

page 47. )

Persons–not classified in (1) or (2)–

with serious continuing activity limitation. This category might be defined in

terms of the two activity limitation

categories, “Persons unable to carry on

the m.:jor activity for their group” and

“Persons limited in the amount or kind

of major activity performed. ” Measurement would r equire c Iassification of degree of limitation of activity for all

persons not classified in (1) or (2) alxme.

(See reference 38. na~es 46. 47.)

(4) Persons–not classified in (l), (2), or

(3) above–who are reported as resmicting their usual activities for the clay in

question. This would correspond to the

“day of restricted activity” concept used

in the Health Interview Survey, but should

be applied only to persons whose usual

activities or mobility are not already seriously restricted by continuing conditions. It would include those hospitalized,

bed-disabled, or absent from work or

school because of transient conditions,

as well as those who cut down on recreational or other activities on the given

day. When desired this category could

be further subdivided according to these

varieties of disability. (See reference 38,

pages 45, 46.)

The particular definitions above could be made

broader or narrower by changing the degree of

disability used as a criterion in categories (2),

(3), and (4), so long as the categories remain

mutually exclusive. Since they are mutually exclusive and the reference period is a single day,

the number of persons in each category is additive and a measure of all persons disabled on

that day is theoretically possible. This would be

a single measure of the impact of morbidity among

the living for that day, and the concept described

might be taken as the unified concept of morbidity

desired.

In practice, a measure for a longer period

such as a year would be desirable and the concept would be measured in a different manner.

Units of time rather than persons would seem to

be the most satisfactory units of count. Armual

numbers or rates for persons or episodes would

be of doubtful meaning or utility unless the variable duration of episodes is taken into account.

All episodes of disability during a year, however,

can be measured in terms of days and, since the

categories are mutually exclusive, the estimated

number of days in each disability category can

be summed to obtain an estimate of total number

of days of disability during the year. For categories (l), (2), and (3), this might be obtained

simply by estimating the annual average prevalence of persons so disabled and multiplying

that estimate by 365. For category (4), which

includes transient disability, current survey

12
methods of estimating annual days of restricted

activity could be used, but persons in categories

(2) and (3) should first be excluded from the data

to avoid duplication in counting. Summing disability days in these four categories automatically weights each episode according to its

duration and provides a measure of the burden

of disability during the year. This might be expressed as an average number of days per person

per year or by some other index.

Use of time units to measure morbidity may

also facilitate the combination of morbidity and

mortality measures into a single index. Although

death and disability are not completely commensurable events, some life table values are

also expressed in units of time.

Potential Sources of Data

The concept of morbidity outlined above is

closely related to measures obtained by the Health

Interview Survey. Its measurement, however,

would require some additional sources of data

and some modifications in current Survey techniques and concepts.

The Health Interview Survey covers the civilian, noninstitutional population rather than “the

entire population. 38 If this source of information

is used to obtain data on disability for an index,

coverage of institutional residents and the military

population needs attention. The institutional population, in particular, is a group for which supplementary sources of periodic information are

essential. Since many institutions exist for the

care of the disabled, estimates omitting this

population would underestimate the total amount

of disability in any given year. Furthermore,

patterns of utilization of institutional care may

change and the bias introduced by omission would

be a variable one distorting comparisons over

time. As the definition of category (1) implies,

estimates of the size of the population residing

in various types of resident institutions would not

be adequate. Residence in many institutions does

not necessarily imply disability. Homes for the

aged, for example, may provide nursing care for

some residents but only room and board for others.

Adequate coverage of morbidity among institutional residents is a problem that must be resolved for any index of health status based on

direct measurement of individual characteristics.

In the Health Interview Survey chronic activity

limitation is an annual item but data on chronic

mobility limitation are collected only at intervals

of several years. The respondent is asked to

classify activity status only for persons reported

as having a chronic disease or impairment. An

index using the morbidity categories described

above would require frequent, possibly annual,

collection of data on these items. It would be

desirable to classify individuals whether or not

chronic conditions are reported. The latter change

in procedure would produce greater conceptual

consistency, since disability as it is defined here

is not a clinical variable. Disability may be

apparent where the underlying clinical conditions

cannot be validly determined without clinical

examination. This might be the case with many

aged persons where feebleness is accepted as an

inevitable concomitant of aging and neither a

diagnosis nor medical care is sought. Classifying

the long-term disability status of all persons

covered by the Survey would not interfere with

the classification of those reporting chronic conditions for other purposes.

The criteria of chronic activity limitation

applied to the aged might also be reexamined.

For other groups the major activity used as a

reference point is a realistic one and describes

behavior commonly expected of members of the

group. There is no role or major activity designated for the aged as such. They are, presumably, classified according to the criteria used

for “workers” or “housewives’’-ability to perform work or housework, respectively. Retirement and some reduction of activity are generally

accepted in our scciety as age increases. Parsons has pointed out the many problems involved

in defining a role applicable to the varied life

situations of older persons in the country. 46

Unlimited work or housework, however, are not

generally expected. Retirement is often mandatory at some age for working men and women and

performance of strenuous household chores is frequently discouraged among older homemakers. A

working solution to the problem of defining longterm disability for this age group might be to

consider institutional confinement and mobility

limitation as the only criteria of disability at

ages 65 and over. Thus those disabled might be

those confined to institutions or to the house and

those unable to move around outside without

13
assistance. This would assume that the aged who

can move about freely in the community are

generally able to care for themselves and carry

on other activities expected in their particular

life situations.

It will, no doubt, trouble many that morbidity measured in terms of interview reports

of disability cannot always be allocated to refined clinical categories in the manner customary

with deaths. Such allocation, however, is possible

with deaths only by adopting the arbitrary convention of assigning each death to a single cause.

While this is often necessary and useful for vital

statistics tabulations it has been criticized as a

misleading oversimplification of the situation in

many cases 3Z~8The idea of a single cause maybe

even less suitable for morbidity than mortality.

It would be convenient to be able to analyze a

measure of morbidity according to the contributions of specific diseases, but for the purpose

of an index, this seems less essential than obtaining a single unitary measure of morbidity.

A measure of disability, as it is defined here,

could be analyzed to show the relative contribution of each category of disability and its

distribution according to age, race, sex, geographic, and other characteristics. In this manner,

changes in index values could be traced to changes

in specific forms of disability in well-defined

population subgroups. The clinical information

obtained from interview survey reports would

not always be adequate to identify the specific

diseases involved, but the effects of broad diagnostic categories such as injuries and respiratory infections might be recognizable. Moreover,

knowledge of the distribution of disability among

demographically defined subgroups is itself useful in delineating the nature and extent of health

problems. It would indicate segments of the

population where health programs could produce the greatest effect. It would also point out

areas where more needs to be known, and the

kind of information needed for a more precise

description and analysis of the problem presented.

Reliability and Validity

A measure of morbidity based upon disability criteria is primarily a social rather than

a medical or biological measurement. The value

of such an index depends upon the reliability and

validity of the component disability measures

under discussion. Both characteristics are matters for empirical investigation, but some general

considerations in evaluation will be mentioned

here.

Reliable measurement requires elimination

or control of extraneous factors influencing the

measurement. Since a primary purpose of a

health index is comparison over time, evaluation

of reliability should take into consideration both

factors influencing measurement under current

circumstances and the possibility of measurements over time being distorted by irrelevant

social changes. Methodological studies have shown

that many aspects of survey procedure influence

the measures obtained. Among these are length

of recall period; relation of respondent to the

individual for whom he is reporting; emphasis

upon specific survey items; duration and inconvenience attendant upon episodes of ill healt~

and differences between interviewers. II-J the

Health Interview Survey control for some of

these factors is built into the design of the

Survey and control for others is achieved through

various field procedures. 49750Whether interviews

or other sources of data are used for an index;

the measures obtained will be dependent upon

many procedural details. A stable system of

data collection is necessary to provide both

continuity of procedure and opportunity for evaluative studies.

Both long-term and short-term disability,

as defined above, reflect individual decisions

which take into account such factors as need

for income, availability of sick leave, pensions

and other support during illness, and the amount

of physical effort involved in the individual’s

occupation and other activities. Over long periods of time, changes in prevailing personnel

policies, in legal regulations, or in the distribution of occupations and income could produce

artifactual changes in the measures obtained.

The only means of dealing with such eventualities are continuous examination of the data

for evidence of such effects and modification or

replacement of the index if it no longer serves

its purpose.

The validity of disability measures based on

interview reports is difficult to evaluate because

there is often no criterion for comparison. If a

14
housewife reports the omission of several chores

she planned to carry out, there is no way to test

the accuracy of her statement. If a worker reports that an upset stomach caused a day of work

loss 2 weeks ago, there may be no way of

knowing whether he was malingering. If interviews are used as a source of clinical data, the

problem of accuracy arises and can be resolved

by comparison of interview data and data derived

from clinical examination—a preferred source.

Clinical data are not an appropriate criterion

here, however, since the individual is asked not

to diagnose his ailment but to state how it

affected his behavior. In many of the instances reported he will be the only person in a position to

know the answer and no better source of information is available for a test of validity by comparison of sources.

Since the validity of disability measures cannot be tested by direct comparison with a criterion

“preferred” source of information, it must be

established by showing that the variable measured

has a necessary position in a theoretical scheme

from which empirically verifiable predictions

can be made. Such a relation has been labeled

“construct validity. !!51Thi6 can seldom be established from a single study or source of data but

must rely on the weight of evidence from diverse

methods and sources.

The validity of disability data based on interview reports will be open to question until

extensive use of such measures in a variety of

studies has established their relation to clinical

measures on the one hand and social variables

on the other. Feldman in evaluating disability

measures points out the need for more methodological studies and voices a suspicion that

data of this type are “ . . . labile reflections

of unstable situational force s.” (See reference

37, page 553. ) Mechanic, however, sees the

interaction of social and biological factors in

the causation of disability as a process which

can be fruitfully investigated and ultimatel y understood by means of appropriate social research

techniques. 52 To resolve such conflicting evaluations more information is needed on how reported

disability varies as clinically determined disease

arises and progresses in individuals. If patterns

of disability reported in interviews are coherently

related to the onset, the progress, and the state

of control of disease in individuals, they can be

used as measures of the impact of morbidity in

a population with greater assurance. Information

is also needed on the personal and social factors

which influence an individual’s decision to restrict his activity temporarily or permanently.

Study of the interaction of these factors in

relation to interview reports of disability carried

out in small groups could provide information

useful in validating and interpreting disability

measures on large populations.

CONCLUSION

The problem of finding a more satisfactory

index of changing levels of health for the United

States population arises from recent changes in

mortality trends and a gradual shift in the

emphasis of health programs toward concern

with nonfatal illness. These developments have

impaired the value of mortality measures as

indicators of the need for and adequacy of health

activities and stimulated interest in finding a

measure which reflects not only the level of

mortality but also conditions among the living.

The notion of health levels is a very general

one and difficult to define preciseIy. Nevertheless, it is widely used in deciding practical

questions concerning the scope and direction of

both private and governmental programs. Its use

implies some methcd of measurement. To accomplish this, however, the level of health of a population must be defined and the definition must be

a measurable one. The considerations discussed

in this report suggested that a definition of health

levels in terms of mortality and morbidity would

be realistic and useful in view of tcday’s health

problems. Morbidity, however, is also a general

term which has been given a variety of meanings.

A concept of morbidity defined in terms of the

disabling consequences of disease and injury

seemed both measurable and pertinent to the

proposed use of a health index. Such a concept

has been outlined.

Disability, as it has been defined here, measures the effects of disease and illness as they

manifest themselves in disruption of social activities. There is general agreement in our society

that disability is per se undesirable. Reduction of

disability ranks with prolongation of life as an

ultimate goal of medical research and practice

and a justification for organizations engaged in

15
these activities. Since disability has this position

in our value system measures of disability can be

interpreted as indications of the need for and the

adequacy of such organized efforts. While this

aspect of disability makes it theoretically suitable,

it also seems to meet the need for a measurable

concept of morbidity. Periods of disability can be

identified and reported by the individual concerned

when suitable interview items have been devised.

Moreover, socially meaningful subclassifications

of disability— such as institutional confinement

and home confinement—can be measured in relation to other characteristics of the individuals

affected. Such possibilities of analysis are important’ if a measure of morbidity is to provide a

guide to the nature and extent of health problems.

These advantages, of course, depend upon the

presumed validity of disability data derived from

interview reports and more empirical evidence

supporting this presumption is needed.

If the level of health of the United States

population is to be measured by an index more

sensitive and more comprehensive than mortality indexes, a measurable concept of morbidity seems essential. The approach outlined here

defines “morbidity” in terms of the total impact

of illness ppon the population and leads to messures of the volume of disability during a year.

These measures can, if desired, be combinecl with

measures of mortality to obtain a single index

reflecting both mortality and morbidity. An index

of this type might use the formula proposed by

Chiang or other methods reflecting different

assumptions and models. 30 Before any index can

be constructed and evaluated, however, there

must be a clear definition of what is to be

measured. This report has reviewed conceptual

problems encountered in deciding what to measure and proposed one method of measurement

that seems both suitable and feasible.

16
*

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Public Health Service. Washington. U.S. Government Printing

Office, hiar. 1964.

2WorId, Health Organization: Constitution of the World

Health Organization, Annex I, in The First Ten Years o~ the

World Health Organization. Geneva. World Health Organization, 1958.

3Dunn, H. L.: Points of attack for raising the level of wellness. J.Nat.M..4, 49(4):225-235, July 1957.

4Galdston, l.: The epidemiology of health, in I. Galdston>

cd., The Epidemiology of Health. New York. Health Education Council, 1953.

5Grundy, F.: Preventive Medicine mtd Public Health, ed.

4. London. H,K. Lewis and Co., Ltd., 1960.

6Leff, S.: Social Medicine. London. Routledge and Kegan

Paul, Ltd., 1953.

7MerreII, M., and Reed, L. J.: The epidemiolo~ of health,

in L Galdston, cd., Sociat Medicine, Its Derivations and Objectives. New York. The Commonwealth Fund, 1949. pp.

105-110.

8Reed, L. J.: Principles applying to the collection of information on health as related to socio-envimnmental factors,

in Backgrounds of Som.al Medicine. New York. Milbank Memorial Fund, 1949. pp. 24-32.

‘Ryle, J. A.: Chan@ag Disciplines. London. Oxford

University Press, 1948.

10Stieglitz, E. G.: The integration of clinical and social

medicine, in I. Galdston, cd., Social iUedicine, Its Derivations and Objectives. New York. The Commonwealth Fund,

1949. pp. 76-89.

1lRogers, E. S.: Human Ecology and Health, An Introduction for Administrators. New York. Macmillan Co., 1960. pp.

153-172.

12United Nations: Report on International Definition and

Measurement of Standards and Levels of Living. U.N. Publication E/CN.3/179,E/CN.5/299. New York. The United

Nations, 1954.

13U.S. NationaI Committee on Vi@l and Heslth Statistics:

Final Report of Subcommittee on the Quantification of W’ellness. Document NC 343, Quant. of Wellness 9. Washington,

D.C. Public Health Service, U.S. Department of Health, Education, and Welfare, Dec. 1960. (mimeo.)

14u.s.National Committee on Vital and Health Statistics:

Report of Ad Hoc Committee on the Possibility of .Measuting

Positive HeaJth. Document NC 261, Positive Health L

Washington, D.C. ‘Public Health Service, U.S. Department of

Health, Education, and Welfare, h{ay 1958. (mimeo. )

15World Health Organization: hfeasurement of leveIs Of

health, report of a study group. W’ld.H?th.Org.Tech .Rep.Ser.,

No. 137. Geneva. World Health Organization, 1957.

16Collins, S. D.: The sickness surveys, types, history and

some results, ch. XXIX in H. Emerson, Administrative ,lieditine. New York. Thomas Nelson and Sons, 1951. pp. 511-535.

17Committeeon the Danish National Morbidity Survey (Lindhart, M.): The Sickness Surwey of Denmark. Copenhagen.

hfunskgaard, 1960.

18CuHumbhe, H.: A surveyof disabling illness in Ceylon.

BulZ.Wld.Hlth.Org. 7:405-429, 1952.

19Department of National Health end Welfare and Dominion

Bureauof Statistics, Canada: Illness and Health Care in Canada, Canadian Sickness Survey, 1950-51. Ottawa. The Queen’s

Printer and Controller of Stationery, 1960.

20Division of Health and Welfare, Japan: The A’ational

Health Surrey in Japan. Document WHOj’HS, National Committee,’92. Geneva. World Health Organization, Jan. 28,

1957. (mimeo.)

21 Dominion Bureau of Statistics, Canad% The Statistical

ileasurernent of Morbidity Frequency. Ottawa. HeaIth and

helfare Division, The Dominion Bureau of Statistics, n.d.

22Slater p . Sun,ey of Sickness, October 1943 tO De~em-

. .

bcr 1945. London. U.K. Ministry of Health, Aug. 1946.

(mimeo.)

23Gt. Brit. General Register Office: The survey of sickness

1943-1952. Studies of Medical and Population Subjects, No.

12. London. H.M. Stationery Office, 1957.

24National Center for Health Statistics: Origin, program,

and operation of the U.S. National Health Survey. Vital and

}Iealth Statistics. PHS Pub. No. 1000-Series l-No. 1. Public

Health Service. Washington. U.S. Government Printing Office,

.hg. 1963.

25Gt. 13rit. General Register Office: The Registrar General’s Statistical Re uierr of England and Wales for the Year

194.9, Supplement on General Uorbidity, Cancer and Mental

Hea.hi. London. H.M. Stationery Office, 1953.

26Swaroop, S.: introduction tn Health Statistics. Edinburgh and London. E. and S. Livingstone, Ltd., 1960.

17
27Swaroop, S., and Uemura, K.: Proportional mortality Of

50 yehrs and above. Brdl.Wld.Hlth.Org. 17:439-481, 1957.

28World Health Organization: Working documents submitted

tn the Study Group on Measurementof Levels of Health. Documents WHO/PHA/Lev. Hlth. /l-l7. Geneva. World Health

Organization, 1955. (mimeo.)

29 Sanders, B. S.: Measuring community health levels. Am.

J. Pub. HeaUh 54(7):1063-1070, July 1964.

30National Center for Health Statisti CS: An index of health,

mathematical models, by C.L. Chiang. Vitat and Health JSta-

&wics. PHS Pub. No. 1000-Series 2-No. 5. Public Health

Service. Washington. U.S. Government Printing Office, May

1965.

31 Gordon, J. E.: The worId, the flesh and the devil as environment, host and agentof disease, in I. Galdston, cd., The

Epidemiology of Health. New York. Health Edu~ation Council, 1953.

32Backett, E. M.: The Measurement of HeoZth and Disease

in a Population. European Conference on Morbidity Statistics

Document EURO-250/5. Vienna. World Health organization,

Feb. 1963. (mimeo.)

33Crew,’ F. A.E~: MecZ8uTt?meVW% of the Public HeaUh.

Edinburgh and London. Oliver and Boyd, 1948.

34Seegal, D.: Disease, disorder and illness, th4l0rrgsiIent period before the onset of symptoms. J.chron.Die. 16(3):

195-197, Mar. 1963.

35 American Public Health Association:A broadened spectrum of health and morbidity. ReIxwtof a workpartyin Report

of the Chairman of the Technical Development Board to tbe

Governing Council, 1959-1960. Am. J. Pub. Health 51(2):287-

294, Feb. 1961.

36 Elinson, J.: Methods ofsociomedical research, cb.18in

H.E. Freeman et al., eds., Handbook of Medical Sociology.

Englewood Cliffs, N.J. Prentice-Hall, Inc., 1963. pp. 449-

471.

37 Feldman, J. J.: The household interview Survey as a

technique for the collection of morbidity data. J.chron.Dis.

11(5):535-557, May 1960.

38National Center for Health Statistics: Health eurvey

procedure. VitaZ and Health Statistics. PHS Pub. No. 1000-

Series l-No. 2. Public Health Service. Washington. U.S.

Government Printing Office, May 1964.

39National Center for Health Statisticw Plan and initial

program of tbe Health Examination Survey. Vitat and Health

Statistics. PHSPub. No. 1000-Series l-No. 4. Public Health

Service. Washington. U.S. Government Printing Office, July

1965.

aSagen, O. K.: Wbatthe Health Examination Survey can do.

J.lndianmed.Prof. 6(6):2804-2805, Sept. 1959.

41Cioc~, A., Graham, S., and Thompson, D. J.: Illness and

receipt of medical services in Pittsburgh (Arsenal) and Butler

County. Penns’.Hlth. 17:2-9, 0ct.-Deg. 1956.

42Maddox, G. L.: Self-assessmentof health etatus, a longitudinal study of selected elderly subjects. J.chron.Dis. 17

(5):449-460, May 1964.

43Suchman, E. A., Phillips, B. S., and Streib, G. F.: Ananalysis of the validity of bealth questionnaires. Social Forces

3~3):223-232, Mar. 1958.

44Apple, D.: Howla~en define illness. Journal of HeaZth

czndHwaanBehaviorI (3):219-225, Fall 1960.

45Bauman, B.: Diversities in conceptions of health end

,physical fitness. Journat of HeaZth and Human Behavior

II(l): 39-46, Spring 1961.

46Parsons, T.: Toward ahea1thmaturity. Journal o/Health

and Human Behavior I(3):163-173, Fall 1960.

47Moriyama, I. M.: Development of the present concept of

cause ofdeatb. Am.J.Pub.Hea?th 46(4):436-441, Apr. 1956.

48 Treloar, A. E.: Theenigma ofcause of death. J. A.M.~.

16~15):1376-1379, Dec. 8,1956.

49Linder, F. E.: Obtaining comparab~lity in field studies

ofgeneral health, in J. Zubin, ed., Field Studies in the Mental

Disorders. New York. Grune and Stratton, 1961. PP.215-232.

50U.S. National Health Survey: The statistical deeignof

the Health Household-Interview Survey. HeaUh Statistics.

PHS Pub. No. 584-A2. Public Health Service. Washington.

U.S. Government Printing Office, July 1958.

51,4mefican psYcbological Association: Technicrdrecommendations forpeychological tests and diagnostic techniques.

Psychol.BuU. 51(2) :13-16 (Supplement, Part 2), Mar, 1954.

52Mechanic, D.: Illness and social disability, mmeproblems in analysis. The Pacific Sociological Revisw 2(1):37-

41, Spring 1959.

ooo —

frU.S. GOVERNMENT PRINTING OFFICE: 1976-- 210-98144

18
.. . .

VITM M@ HMZWI ST@$TICS FU8LlCATtC3t4 SERIES

(%i$#?kliiy f%blk Health S6rvke hblkdion No. 1000

,

Series 1. Pmgmms and edlection procedures. -Rqw.t’ts@tfcb describe the general programs of the National

center fox+Healtp -S!atiE@cSand i~s O*C+ a~ ~ViSiOW data Coll=tfon tne~hods used. definitions,

and i%her matqrkl necessary for understanding the data.

Series 2. ‘Da+ W@tiatwn and methods restmrck -Sttdtes of new statistical methodology includi~g: experimental teste of new survey methods, studies of vftai statistics collection methods, new analytical

techniques, chjeetive evaluations of reliability of collected data, contrihutfons to statistical theory.

Series 3. AnaltWui dudies.-Report8 presenting analytkal or interpretive studies baaed on vital and health

att@stics, carrying the analysis further than the expository types of reports in the odter series.

Series 4.

Series 10.

Seties 11.

Sw”es 12.

Series 13.

Series 14.

Se7ies 20.

series 21,

Series 22.

Documants and committee re#orts.-Final reports of major committees concerned with vital and

health statistics, and documents such as recommended model vital registration laws and revised

Mr.@andde@t .fiewtificates.

Rah $%@? the Walth Interviti Survev.-Siat@ti@ on flhtess, accidental injuries, disaMlity, use

of ,hospftal, medieal, dental, and other servicgts, and @her Wsldt-relatecl topbts, based on data

collected in a continuing national household ittterv:ew survey. ‘ “

Data & the Health Examinatkm Survey, -Data from direct examination, testing, and “measurement of natfooal samples of the civilfan, notdnstitutional populadon provide the basis for two types

of rsporm: (1) estimates c!f the m&dlcal@ defined prevalence of specific diseases in the United

States aod the distributions of the “jmpulation with respect m physical, Physiological, and psychological c~raccerimics; and (2) analysis of relationships among the various measurements without

reference to an explicit finite universe of persons.

D@ porn the Institutional Popuktion Surtieys.- Sta&t@ relating to the health characteristics of

persons in institutions, and their medkxli.nursing, and per~~ G=e x=c~ived, ~S@d on national

saiqdes of establishments providing rhese services and 6ampks of the resfdente or patienta.

Data j%o??t the Hospital Discharge Survey. — Statistics relating to discharged patients in short-stay

hospit.alq based on a sample of patient records in a national sample’ of Imepitals.

Dab’ on health resowrces: manboti and facilities. —Statistics on the numbers, geographic distri -

butfofi, and characteristics of health resources including physicians, dentists, nurses, other health

occupations, hospitals, nursing ”homes, and outpatient facilities.

DatQ on mon221ity.— Various statistics on mortality other than as inc~udeci in regular annual or

monthly reports— special analyses by cause of death, age, and other demographic variables, XISO

geographic and time series analyses.

Data on natality, marriage, and diwwe. —Various statisti::~ (>n nataiity, marriage, and divorce

other than as included in regular annual or monthly rqmrts-speciai analyses by demographic

variables, also geographic and tfme series analyses, stdet. of fertiliry,

DOta from the National Natality and Mortality SUTLV?YS.— Statistics on characteristics of births

and deaths not available from the vital records, based on sample surveys stemming from these

records, including such topics as mortality by scxioeconornic ciass, hospital experience in the

last year of life, medical care during pregnancy, health insurance coverage, etc.

n For a list of titles of reports published in these series, write to: Office of lriformation

National Center for Hea!th Statistics

Public Health Service, l{R.A

Rockvifle, Md. 20852
U.S. DEPARTMENT OF

HEALTH, EDUCATION, AND WELFARE

POSTAGE AND F’EEe PAID

Public Health Service LI.9DEPARTMENT OF HEW

Health Resources Adlni]~is[ration 390

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Penaity for Private User $300

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For pub!ic;ifims iti the

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