a validated for use in population surveys of …jech.bmj.com/content/jech/25/2/97.full.pdf · a...

Brit. J. prev. soc. Med. (1971), 25, 97-104

A VALIDATED INTERVIEW SCHEDULE FOR USE INPOPULATION SURVEYS OF CHRONIC DISEASE

AND DISABILITY

JESSIE GARRAD* AND A. E. BENNETTtDepartment of Clinical Epidentiology and Social Medicine, St. Thomas' Hospital Medical School, Loncdon S.E.1

The popular concept of a disabled person is ofsomeone who has lost a limb or who is physicallydeformed in some obvious way. This concept islargely based on the appreciation of structuraldamage; severity is considered to be dependent onthe extent of the damage and criteria based on thisapproach govern the assessment and award of thedisability pensions at present available. However,disability may be thought of in terms of behaviourand performance and may be considered as limita-tion of the performance of an individual whencompared with a 'fit' person. This concept considersdisability as a disorder of function rather than astructural abnormality or loss. In America, reportsof the Committee on the Medical Rating of PhysicalImpairment (1958) distinguish between these twoapproaches. The concept of the total functionalloss is considered to be disability whereas theanatomical or structural abnormality is describedas impairment.We have adopted this distinction but define these

two terms more strictly. We define disability aslimitation of performance in one or more activitieswhich are generally accepted as essential basiccomponents of daily living, such that inability toperform them necessitates dependence on anotherperson. The severity of disability is thus propor-tional to the degree of dependence. The areas ofactivity essential are (I) mobility: walking, negotiat-ing stairs, transfer in and out of bed or chair, andtravel; (2) self-care: feeding, dressing, and toiletcare; (3) domestic duties: shopping, preparationand cooking of food, household cleaning, and wash-ing of clothes; and/or (4) occupation: the ability tohold unmodified employment in open industryconsistent with the individual's age, sex, and skill.We define impairment as an anatomical, patho-

logical or psychological disorder which may bedescribed in diagnostic or symptomatic terms. It may*Present address: Department of Social Work and Administration,University of Bristol, 6 Berkeley Square, Bristol.tPresent address: Department of the Regius Professor of Medicine,University of Oxford, 9 Keble Road, Oxford.

cause or be associated with disability so that whileevery disabled person has an impairment, not allpeople with impairments are necessarily disabled.Impairments may be classified into four categories:those affecting locomotion or any motor activity;those of sensory origin; those referable to internalmedicine, e.g., cardiac and respiratory disorders;and those of primarily psychological origin togetherwith unclassifiable organic disorder.

MEASUREMENT OF DISABILITYThere are three main methods by which disability

defined in functional terms can be identified andmeasured. The first of these is by clinical assessmentof the individual's performance. Unfortunately,however, it has been shown that observers of differ-ent professional disciplines use different criteria forassessing performance (Kelman and Willner, 1962).Moreover, perception of change in an individual'sperformance is related to the observer's role in thetreatment and assessment situation (Tamerin, 1964).If an attempt is made to overcome these difficultiesby forming a team of several clinical disciplines tomake the assessment, unanimity is unlikely. Theoptions then are either to accept democraticallythe majority opinion, to 'weight' the opinions of thevarious observers or to accept that the leader of theteam has the prerogative to resolve any difference(Kelman and Willner, 1962). These difficulties aremore easily resolved in the clinical situation, and themethod presents considerable organizational prob-lems for large-scale surveys.The second principal method involves the use of

standard tests of performance by the individualconducted by an observer trained in the adminis-tration of the test. Examples are the MarylandDisability Index, also known as the Barthel Index(Wylie and White, 1964) and the Index of Independ-ence in Activities of Daily Living (Index of A.D.L.:Katz et al., 1963). In these scales, a number ofactivities is defined which an individual must beable to complete unaided in order to live an inde-

97

on 4 July 2018 by guest. Protected by copyright.

http://jech.bmj.com

/B

r J Prev S

oc Med: first published as 10.1136/jech.25.2.97 on 1 M

ay 1971. Dow

nloaded from

http://jech.bmj.com/

JESSIE GARRAD AND A. E. BENNETT

pendent life. The individual's performance isobserved and his level of independence in eachactivity is rated according to carefully definedcriteria. In a variation of this method, the individualis tested for his ability to make the basic movementsneeded to perform these activities rather than hisability to perform the activities (Jefferys, Millard,Hyman, and Warren, 1969).However, with any tests of performance the

problem of the effect of interaction between theindividual, the observer, and the test situation isimportant (Wolf, 1950; Osgood and Suci, 1952;Shontz and Fink, 1957; Cole and Griffith, 1958).Kelman and Willner (1962) obtained three differentscores when patients resident in a nursing home wererated under three different sets of conditions: innon-test, day-to-day conditions in the nursing homerated by staff familiar to them; in a test situation intheir nursing home rated by staff familiar to them;and in a test situation outside their nursing homerated by unknown staff. In general, the test situationoutside the nursing home with unfamiliar observersproduced the lowest ratings. However, some patientsappeared to be so stimulated by the novelty of thestrange situation as to perform better: this pheno-menon was also reported by Muller (1961).

Closely associated with the variation in perform-ance due to rapport between individual and observerand the effect of the test situation is the factor ofthe individual's self-concept. Litman (1962, 1964)has shown that patients' progress in rehabilitationis largely dependent on their self-concept. If theyconsider themselves to be capable of playing adefinite, although altered, role in society, theyrespond better to treatment than if they considerthemselves as disabled and limited people. It isarguable that a person's performance in a testsituation would be affected in a similar way. Anothercomponent of the individual's motivation which mayaffect performance is the secondary gain which hethinks may result from performing well or badly.The third method is by questioning the individual

as to his current level of daily performance. Com-munication difficulties and confusional states mayrender this method impossible or unreliable. Forthis reason Sett (1963), in his questionnaire, includeda section to assess communication and mentaJ statewhich is administered first and, if necessary, theremainder of the questionnaire is then administeredto a relative or member of the nursing staff. Whenthe respondent answers for himself, problems ofself-concept and secondary gain are also relevantin this method. While the importance of the latterproblem is considerable in the clinical situation it isminimal in research, and the effect of the former

problem can be identified by built-in cross-checksin the interview.When using an interview technique in research

surveys the problems of interviewer variation andinterviewer drift arise. The former can be reducedby strict training and supervision and the latter byperiodic check interviews. Of great importance is theeffect of the interaction between the interviewer andthe respondent. Cannell and Marquis (1967), andCannell, Marquis, and Laurent (1969) have shownthat the quantity and quality of data obtained inhealth surveys is dependent on the attitude andmanner of the interviewer and the style of inter-viewing. Again, standardization can be obtained bytraining and supervision but the possible effect ofthe interviewer's sex on the validity of the datacollected should not be overlooked (Colombotos,Elinson, and Loewenstein, 1968).

DEVELOPMENT OF INTERVIEW SCHEDULEThe prevalence of disability has not been exten-

sively studied and an almost complete lack of anyknowledge about the size and nature of the problempresents difficulties in planning health and welfareservices. For this reason and because of the increas-ing importance of chronic non-communicabledisease as a cause of morbidity in middle and oldage we wished to measure the prevalence of disa-bility in the population of the catchment area of St.Thomas' Hospital. Comparison of the three methodssuggested that the interview was the method ofchoice for a large-scale survey conducted in therespondents' homes. We now describe how astructured interview schedule was developed andtested for this study. Section I of the interviewschedule identifies and assesses the severity ofdisability and section II classifies the impairment andidentifies the principal diagnostic group. Subsequentsections of the schedule, which are not describedhere, deal with occupational history, family, accom-modation, and the use of health and welfare services(schedule available on request).

SECTION I: ASSESSMENT OF DISABILITYThis section was developed in three stages. The

content was determined by the definition of theessential activities of daily living. Then a series ofquestions was formulated to identify the respon-dent's maximum level of unaided performance ineach activity or, if some help was essential, hismaximum performance in each activity with theminimum of help. Criteria to identify disability ineach area of activity and the different levels ofseverity were at first arbitrarily set from clinicalexperience. The questionnaire was then tested on a

98


http://jech.bmj.com

/B

r J Prev S


ay 1971. Dow

nloaded from


POPULATION SURVEYS OF CHRONIC DISEASE AND DISABILITY

SECTION I

MOBLIT"Y

Wwwaff, Do you wal outdoors in th srea (with cruc or sic if used)?

If 'Yes: one mile or more

i mile ElIoo yds. El

io yds. E1

If No':Between rooms

Within room

Unable to walk

ElElEl

and:Unaccompanied

Accompaniod Ei

AGC. + support El

Stairs Do you walk up stairs?

To ist floor or above [115-8 steps or stairs []

2-4 steps or stairs E

I step Elmount sta otherthan by walking Elunable to mount stairs El

Unacc.

Acc.

Acc. & Supp.

OlElE*l

No need to nmount stairs L i

Do you walk down stairs?

From I floor to another I]

5-8 steps or stairs E[2-4 steps or stairs El]

I step [

goes down stairs otherthan by walking IDunable to descend stairs El

Unacc.

Acc.

Acc. & Supp.

ElF]El

No need to 1-descend stais

TranserYes NO Yes No

Do you need help to get into bed? E. El Do you need help to sit down in a chair? II]i :IDoyouneedhelp togetoutof bed? . I l2 | Do you need help to stand up from a El []chapic?... ... ...

Bedfast ... ... .. ... F]i Not applicable ... .. ... E]r -~~~~~~~~~~~~~~~~~~

Travel

Do you drive yourselfin a car?

Normal (unadapt.) LI

Adapted [

Invacar ElSelf-propeled vehicle

(outdoors) El

Does not drive [

Do you travel by bus or train ?

If 'Yes':Whenever necessary I]

Only out of rush hour Eland:

Unaccompanied []

Accompanied [E

If 'No':

Unable to use bus and train

Unable to use bus, train and car

Does not travel by choice

Uses private transport by choice

F]

ElEl[2

I

99


http://jech.bmj.com

/B

r J Prev S


ay 1971. Dow

nloaded from



SELF CAE

Are you able to Are you able to dressfeed yourself: yoursdf completely:

Are you able toundress yourselfcompletely:

Are you able to use Are you able tothe lavatory: wash yourself:

Without any help

O'With speciallped food or

cd~IWith assistance

I]Not at al, must befed

Without any help

ElWith help with

fastenings

ElWith help other thanfasteings

Does not dress

El

Without any help

L]With hdep with

fastenigs

With help other thanfastenings

ElNot applicable

Without any help

LI1Roceptacles without

asssace

ElLavatory with

ElReceptacleswith

El

Without any help

OWith assstance for

-vng combing

hakr, et.El

With hep for bodily

ElNot at all

DOMESTIC DUTIES Do you do your own:

Shopping

Cooking

a ing

Clothes washing

Men with no household duties

an d ar none

El

O O [I

preference unable

ElElEl

ElLI

Do you have a paid job at present?

and:Normal working LI

Modified woring El

Sheltered employment El

* CROSS IN ANY BOX MARKED WITH AN ASTERISK INDICATES PRESENCE OF DISABILITY

OCCUPATION

If 'Yes':

Full time F]Part-time a1

If 'No':

Males 65Females 6o

andovaer

Males 64[Female 59 .

and

underI

Age retired

Prem. retired

Non-employed

Unemployed

Unfit

Non-employed

0ElLLEL

I I I

100


http://jech.bmj.com

/B

r J Prev S


ay 1971. Dow

nloaded from



wide range of inpatients and outpatients for mean-ingfulness, intelligibility, and acceptability. It wasrepeatedly modified and retested until satisfactorywording and grading were obtained. FinaUy thelayout was designed in a condensed format so thatthe various subsections were conveniently and clearlyset out for the interviewer to complete with theminimum of clerical error (section I of schedule).Each subsection is introduced by a lead question

asking in most instances 'Do you. ..?' rather than'Can you...?' or 'Could you if...?' Interviewerswere trained to probe to identify the appropriatelevel of performance. When a respondent's answerfell between two defined levels of performance thehigher level was recorded so that disability wasunderestimated rather than overestimated.

It can be seen that the separate criteria for disa-bility are: walking less than j mile unaccompanied;walking up or down less than nine stairs unac-companied; needing help to get in or out of bed orchair; using an invacar or self-propelled vehicleoutdoors; inability to travel by public transport un-accompanied whenever necessary; needing specialfacilities for feeding; needing assistance withpersonal washing; inability to perform all thedefined domestic duties; inability to undertake un-modified employment if of working age, or havingretired prematurely on medical grounds if currentlyover retirement age. Initially, if an individual metany one of these criteria he or she was classified asdisabled. However, it became apparent that all thesame criteria could not meaningfully be applied topeople aged 65 or over, especially in the area oftravel and domestic duties. Therefore, for this agegroup only, these criteria were modified to accept alower level of performance as adequate and notindicative of disability. For the majority of men over65 occupation does not demand the ability to travelon public transport unaccompanied at any time, sothis criterion, applicable to the younger age groups,was relaxed. For women over 65 domestic dutiesbecome more onerous and many women are notable to maintain their levels of activity. Since there isin the performance of domestic duties a largequalitative component, the criteria for those over 65were relaxed so that accomplishment of only part ofthe household duties did not imply disability as it didin the younger age groups.

Scoring presented problems. Many rating scalespresent a score calculated as an algebraic sum ofthe component scores. This, however, masks differ-ent levels of performance in different areas, resultsin loss of information, and can be misleading. Also,for the purpose of assessing medical care needs, it isnecessary to know in which areas of activity the

respondent's performance is deficient so that theappropriate health or welfare service may be selectedto assist him.Ekwall (1966) reviews several methods of assess-

ing disability in which 'socio-medical' and 'psycho-social' factors are considered to be relevant variables.A particular value of his paper lies in a descriptionof the method whereby a large amount of data isquantified and summarized without loss of relevantinformation. We adopted a similar method ofscoring to quantify the level of performance in eachessential activity of daily living and designed amethod of coding the information for data process-ing. Each individual is described by four scores, onefor each area of essential activity, and these scoresmay be presented as a profile.

SECTION II: IDENTIFICATION OF IMPAIMENTA locomotor impairment was identified by four

questions enquiring for permanent paralysis orweakness of specified parts of the body-by painand by limitation ofmovement in specifiedjoints. Theinterviewer noted tremor of hands and/or speechinterference and recorded any comments volunteeredby the respondent. A sensory impairment wasidentified by questions devised to assess loss of hear-ing, defective vision, loss of tactile sense or appre-ciation of temperature and disturbance of balance.The subsection for internal impairments consistedpartly of the questionnaire on respiratory symptoms(Medical Research Council, 1966) and part of thequestionnaire for the diagnosis of ischaemic heartpain (Rose, 1962) with additional questions designedto identify, for example, the presence of diabetes.A structured subsection enquiring for past

medical history and medical care usage in the previousnine months often provided confirmation of theimpairment identified by the preceding sections.Respondents suffering an impairment which couldnot be confidently allocated to one of the first threecategories were allocated to the fourth category of'other' together with those whose impairment wasclearly of psychological origin. A psychologicalscreening questionnaire (Foulds, 1965) was in-cluded in section II to give a measure of 'personaldisturbance'.These two different sections were reworded and

retested until they were intelligible to a sample ofpatients, and the data obtained broadly correspondedwith information available in the medical notes. Thedesign was amended until the lay-out was con-venient to the interviewer.

VALIDATIONThe validity of these two sections was measured

101


http://jech.bmj.com

/B

r J Prev S


ay 1971. Dow

nloaded from



by comparison with clinical assessments. TheDepartments of Geriatrics and of Physical Medicinemaintain detailed records of the patients' perform-ance and much additional data and social informa-tion are available in the records of the medical socialworkers. Fifty-two outpatients attending thesedepartments were selected for us by the staffs of thedepartments. These patients were seen at home bytrained interviewers who had no prior knowledge ofthe patients. Before the interview was started it wascarefully explained that it was part of a researchprogramme and not part of treatment. The datarecorded in the completed interview schedules werethen compared with the medical and social workrecords.The patients, 17 men and 35 women, were aged

between 35 and 74 years. The clinical records showthat five were impaired only, five disabled in one areaof essential activity, 18 in two areas, 19 in threeareas, and five in all four areas. The primary diag-noses of the 52 patients were: rheumatoid arthritis,arthritis, etc., 22; cerebrovascular disease, 9;neurological disease including sensory disorders, 10;cardiovascular, respiratory, and other internaldisorders, 10. In one patient the primary diagnosiswas psychological disorder but the patient alsosuffered from cervical spondylosis.

Table I shows the agreement of the completedinterview schedule with the clinical record. In allcases the disability status was correctly described.Two errors occurred in allocation to the impairmentcategory and three errors in identification of theprimary diagnosis. These five errors concerned threepatients. The impairment category of the patientwith psychological disorder was incorrectly assignedas a result of the diagnosis of spondylosis; no diag-nosis of psychological disorder was made. Adiagnosis of congestive cardiac failure and allocationto the category of internal impairment were in-correct in a patient suffering-from arthritis, obesity,and diabetes. In the third patient the correct diagnosisof osteoporosis was not made and cerebrovasculardisease was diagnosed. The clinical records of the52 patients revealed disability in a total of 18 areas

TABLE IVALIDATION OF INTERVIEW SCHEDULE

(Agreement of the interview schedule with the clinical record inassigning the respondent to the correct disability status, impairment

category, and diagnosis)

% Correctly Assigned(n = 52)

Disability status 100Impairment category 96Primary diagnosis 94

TABLE IIRELIABILITY OF INTERVIEW SCHEDULE

(Comparison of assessments made one year apart by differentinterviewers on 153 respondents)

1968 Second Assessment

1967 Fit Impaired Dl D2 D3 Total

Fit 49 1 1 - 1 52a Impaired - 43 4 2 3 52E DisabledE Severity0 groupi - I 1 5 1 3 20<: group 2 - 1 2 4 - 7

group 3 - - 1 21 22Total 49 56 12 8 28 153

and of these 108 (91-5%) were recorded at interview.In addition to these 10 false negatives, the interviewschedules contained one false positive identificationof disability in the area of occupation.

RELIABILITYThe reliability of this interview schedule was

assessed when 153 respondents (90 women and 63men) in a population survey were re-interviewedafter 12 months by a different team of interviewers.Table II shows that two respondents previouslyclassified as fit and nine previously classified asimpaired only were reclassified as disabled. Thediagnoses in these nine impaired cases were chronicbronchitis (3), cerebrovascular disease (2), rheuma-toid arthritis, rheumatic heart disease, musculardystrophy, and ulcerative colitis. In all these casesthere was indirect evidence in terms of hospitalattendances and general practitioner consultationsto indicate that their condition had worsened duringthe intervening year. The diagnoses in the two res-pondents previously classified as fit and becomingdisabled during the year were epilepsy anddepression.Twelve respondents originally classified as disabled

were reclassified as impaired. In nine of these caseswho suffered from prolapsed intervertebral disc(3), arthritis (2), Parkinson's disease, epilepsy,chronic bronchitis, and internal derangement of aknee joint, there was evidence to support the change.For instance, the woman suffering from Parkin-son"s disease had undergone surgery with remark-ably good effect. In three cases, however, whosuffered from rheumatic heart disease, angina, andbronchiectasis, there was nothing recorded in theinterview schedule to explain the change in classifi-cation. Seven respondents showed a change inassessment of severity of disability, three improvingand four worsening. In all seven these findings werein respondents suffering from conditions in which thedisability would be expected to fluctuate.

102


http://jech.bmj.com

/B

r J Prev S


ay 1971. Dow

nloaded from



Complete agreement between assessments oc-

curred in 122 (80%) people. Agreement in theidentification of the presence or absence of disa-bility occurred in 130 (85%) people. In only threeout of 153 reassessments after an interval of oneyear did change occur which could not be explainedand these levels of repeatability were consideredsatisfactory.

DiscussioN

In a previous report we described the use of theinterview schedule for the second stage of a large-scale population survey with a sample of 1,142adults aged 35 to 74 (Bennett, Garrad, and Halil1970). The results showed central estimates of7*2% men and 9 7% women disabled according tothe definition and criteria stated.As preparation for the field work of this study a

training programme was organized lasting approxi-mately three weeks for each new interviewer andthey were trained in small groups. The trainingconsisted of three stages. First, the principles onwhich the schedule had been developed were care-fully explained and the method of administrationwas demonstrated in simulation role-playing inter-views by the two of us. Then the interviewers tookit in turns to interview each other in our presenceand their performance was commented on. Secondly,they practised the interview on inpatients and out-patients, again under observation by one of us.Finally, they completed a series of interviews onselected outpatients in their homes. Each interviewschedule was scrutinized by one of us for complete-ness and internal consistency and the data werediscussed in detail with the interviewer. When neces-sary, these were checked with hospital records or

with the patient. During the survey, a similar pro-cedure to the last stage of training was followed.Each schedule was scrutinized on the day followingthe interview and, when necessary, omissions werecompleted by a repeat visit. Schedules were dis-cussed with the interviewers to cross-check onaccuracy and to minimize variation between inter-viewers and interviewer drift. Seventeen inter-viewers took part in the field work which lasted forjust over three months.The second stage of the study was restricted to

persons aged 35 to 74 years. Below this age thenumber of disabled in the first stage sample wastoo small for estimates of prevalence to be made.By contrast, over the age of 74 the proportion ofthose functionally disabled rose very sharply,reflecting how the processes of increasing severityof disease with age restrict function and result independence.

This illustrates the dynamic nature of this con-

ceptual model of disability. An infant born 'fit'and continuing to survive will progress to becomeimpaired and subsequently disabled. The usualsequence of events is for the period of 'fitness' toend in middle age or later with the manifestationof one or more of the chronic degenerative diseases,most commonly of locomotor or internal origin.As the disease progresses the individual loses hisindependence of living and thereafter becomesincreasingly disabled. However, for each individualthe time periods of the different stages will vary.Following the onset of diseases such as rheumatoidarthritis or multiple sclerosis, the period of disa-bility may extend to many years, whereas after asevere stroke or the onset of some malignant condi-tion the period may be short. An infant born with acongenital abnormality is impaired and possiblydisabled throughout life. A child involved in anaccident may lose a limb and be impaired for lifebut only becomes disabled when the effects of ageingsupervene. Death is an event which at some pointintervenes to prevent further progression. Acuteillness with cure or recovery from a chronic condi-tion both show how the model need not be con-sidered unremittingly progressive, even in the shortterm.The critical point in the progression is when

independence of living is lost and disability ensues.Obviously this is not as sharp a point of demarcationin all cases as would be desired for the purposes ofmeasurement. If acute illness is excluded by settinga minimum time qualification, such as three months,factors causing oscillation at this point are changesin severity of the disease or changes in the psycho-logical state of the patient. If these are liable tofluctuate then the individual's ability to performtasks unaided may vary. Table II shows that by farthe largest number of individuals who were reclassi-fied one year later were changed from the minimallydisabled to the group of impaired only or vice versa.However, in the same way as fluctuation or

remission in the severity of a disease process allowsindependence to be regained, so may treatment orthe provision of aids or gadgets restore the neces-sary function. Thus a simple dressing aid or walkingstick may restore enough function to allow inde-pendence. These may, however, be required in addi-tion to a major operation such as hip arthroplasty.The objectives of the surgical procedure or use ofthe gadgets are all similar in attempting to restoreand maintain the ability of the individual to functionindependently, or to function to the best of limitedabilities. It is not difficult to refer these same objec-tives to the practice of internal medicine or psy-chiatry or even to offer them as the objectives for

103


http://jech.bmj.com

/B

r J Prev S


ay 1971. Dow

nloaded from



the practice of medicine. For in many of the chronicconditions presently treated, progression of thedisease is largely unaffected. Functional evaluationof the effectiveness of many widely used treatmentsor procedures is required.The present schedule was not designed for use in

the clinical' situation. Furthermore, the problem ofsecondary gain, which is minimal in the researchsetting, may prove of some importance when using

such a schedule for clinical assessments. However,no method will overcome this or all other possibledisadvantages. Further work is now examiningwhether the coarse scaling of this instrument' de-signed for epidemiological surveys can be refinedto extend its usefulness into the area of evaluatingthe outcome and effectiveness of various treatments.

SUMMARYA concept of disability is put forward based on

appreciation of inability to perform essential acti-vities of daily living. Inability to perform theseactivities unaided necessitates dependence on ano-

ther person and the severity of disability is propor-tional to the degree of dependence. A review ofpublished evidence suggests that the interview isthe method of choice for population surveys tostudy the epidemiology of disability as defined.The development of sections of an interview scheduledesigned to assess disability and identify the asso-

ciated impairment category and diagnostic groupis described. Comparison of data obtained bytrained interviewers using the schedule with datarecorded in the clinical record showed levels ofagreement between 90 and 100%. For a series ofassessments repeated after an interval of one year,agreement was found in 80% but in only 2% were

the changes inexplicable.These studies were supported by the Endowment

Funds of St. Thomas' Hospital, the Department ofHealth and Social Security, the South-West MetropolitanRegional Hospital Board, and the City ParochialCharities. We wish to thank Professor W. W. Hollandfor advice and encouragement; Drs. T. C. Picton Williamsand D. A. H. Yates for generous help and permissionto study their patients; Miss S. Smeeton for secretarialsupport; and all members of the department who assistedus.

REFERENCESBENNETr, A. E., GARRAD, J., and HALIL, T. (1970).

Chronic disease and disability in the community: a

prevalence study. Brit. med. J., 3, 762.

CANNELL, C. F., and MARQuIs, K. H. (1967). Effect ofsome experimental interviewing techniques on re-

porting in the Health Interview Survey. SurveyResearch Center, University of Michigan.

,q ~~, and LAURENT, A. (1969). An experimentalstudy of the effects of reinforcement, question lengthand re-interviews on reporting selected chronicconditions in household interviews. Survey ResearchCenter, University of Michigan.

COLE, S. L., and GRiFFiTH, G. C. (1958). Assay ofantianginal agents-the rapport period. J. Amer. med.Ass., 168, 275.

COLOMBOTOS, J., ELINSON, J., and LOEWENSTEIN, R.(1968). Effect of interviewers' sex on interview res-ponses. Publ. Hlth Rep. (Wash.), 83, No. 8, 685.

COMMuITEE ON THE MEDICAL RATING OF PHYSICALIMPAIRMENT (1958). A guide to the evaluation of per-manent impairment of the extremities and back.J. Amer. med. Ass., 166, Feb. 15th, Special edition.

EKWALL, B. (1966). Method for evaluating indications forrehabilitation in chronic hemiplegia. Acta med. scand.,Suppl. 450.

FOULDS, G. A. (1965). Personality and Personal Illness.Tavistock Publications, London.

JEFFERYS, M., MILLARD, J. B., HYMAN, M., and WARREN,M. D. (1969). A set of tests for measuring motorimpairment in prevalence studies. J. chron. Dis., 22,303.

KATZ, S., FORD, A. B., MosKowlTz, R. W., JACKSON,B. A., and JAFFE, M. W. (1963). Studies of illness inthe aged. J. Amer. med. Ass., 185, 914.

KELMAN, H. R., and WILLNER, A. (1962). Problems inmeasurement and evaluation of rehabilitation. Arch.phys. Med., 43, 172.

LITMAN, T. J. (1962). The influence of self conception andlife orientation factors in the rehabilitation of theorthopedically disabled. J. Hlth hum. Behav., 3, 249.

(1964). An analysis of the sociologic factorsaffecting the rehabilitation of physically handicappedpatients. Arch. phys. Med., 45, 9.

MEDICAL RESEARCH CouNciL (1966). A questionnaireon respiratory symptoms approved by the M.R.C.Committee on Research into Chronic Bronchitis.

MULLER, J. N. (1961). Rehabilitation evaluation-somesocial and clinical problems. Amer. J.pub. Hlth, 51,403.

OSGOOD, C. E., and SucI, G. J. (1952). A measure ofrelation determined by both mean difference andprofile information. Psychol. Bull., 49, 251.

ROSE, G. A. (1962). The diagnosis of ischaemic heartpain and intermittent claudication in field surveys.Bull. Wld Hlth Org., 27, 645.

SErr, R. F. (1963). Simplified tests for evaluation ofpatients with chronic illness (cerebro-vascular acci-dents). J. Amer. Geriat. Soc., 11, 1095.

SHONTZ, F, C., and FINK, S. L. (1957). The significanceof patient-staff rapport in the rehabilitation of indi-viduals with chronic physical illness. J. consult.Psychol., 21, 327.

TAMERIN, J. S. (1964). The perception of progress inrehabilitation. Arch. phys. Med., 45, 17.

WOLF, S. (1950). Effects of suggestion and conditioningon the action of chemical agents in human subjects:the pharmacology of placebos. J. clin. Invest., 29, 100.

WYLIE, C. M., and WHmrE, B. K. (1964). A measure ofdisability. Arch. environm. Hlth, 8, 834.

104


http://jech.bmj.com

/B

r J Prev S


ay 1971. Dow

nloaded from


a validated for use in population surveys of …jech.bmj.com/content/jech/25/2/97.full.pdf · a...

Documents