J7ournal of Epidemiology and Community Health 1996;50:149-155

The effects of illness on quality of life: findingsfrom a survey of households in Great Britain

Ann Bowling

AbstractStudy objective - To obtain national popu-lation norms on pertinent domains ofqual-ity of life, and the relative importance ofthese domains to people with reportedlongstanding illness.Design and setting - The vehicle for thestudy was the Office of Population Cen-suses and Surveys omnibus survey inGreat Britain. The sampling frame wasthe British postcode address file of "smallusers", stratified by region and socio-economic factors. This file includes all pri-vate household addresses. The postalsectors are selected with probability pro-portional to size. Within each sector 30addresses are selected randomly with antarget size of 2000 adults.Participants - The total number of adultsinterviewed was 2033 (one per sampledhousehold), resulting in 2031 usable ques-tionnaires, and representing a responserate of 77%.Main results - Of those who reported alongstanding illness, the most common,freely mentioned, first most importanteffects of the longstanding illness on theirlives were (in order of frequency) abilityto get out and about/stand/walk/go outshopping, being able to work/find a job,and effects on social life/leisure activities.Analysis of the areas of life affected bylongstanding illness, showed considerablevariation in relation to the condition. Forexample, respondents with mental healthdisorders (mainly depression) were mostlikely to report as thefirst most importanteffect the availability of work/ability towork, followed by social life/leisure ac-tivities; respondents with digestive and en-docrine (for example, diabetes) disorderswere most likely to report dietary re-strictions; while respondents with cardio-vascular disease, respiratory, andmusculoskeletal disorders were most likelyto report ability to get out and about/stand/walk/go out shopping.Conclusions - These results support thecurrent trend of developing disease spe-cific health related quality of life ques-tionnaires rather than using genericscales.

(J7 Epidemiol Community Health 1 996;50: 149-155)

There is increasing agreement among manyclinicians and social scientists that quality oflife should be assessed when evaluating theoutcome of medical interventions. It is com-

mon for investigators to use traditional healthstatus measurement scales to measure healthrelated quality of life, on the basis of the usuallyunquestioned assumption that the concepts areinterchangeable. The construct validity ofscales is called into question by this in-terchange. None of the health status scaleshave been rigorously assessed for their contentvalidity as measures of health related quality oflife, and none are based on the public's (healthyor unhealthy) definitions ofthe important areasof measurement in relation to health relatedquality of life. Most scales were developed onthe basis ofreviews of existing scales, or surveysof the public's perceptions of the effects ofillness on behaviour or functioning. `' The pub-lic, and specific groups of patients, are the bestjudges of how medical conditions adverselyaffect their quality of lives. However, the rel-evant dimensions of health quality of life whichshould be included in measurement scales isstill the subject of vigorous debate and dis-agreement, partly because few scales have beendeveloped and rigorously tested using suffi-ciently large samples of people.

Attention is now being paid to disease spe-cific measures of quality of life which attemptto tap domains that are relevant to peoplewith specific conditions. Generic scales canbe criticised for containing items that may beirrelevant to people with the condition understudy, and for omitting others that are per-tinent. Few disease specific or generic in-struments have been based on a model ofquality of life, few scale developers have at-tempted to define this concept, and few havebeen adequately patient based in their de-velopment, with most being based on healthprofessionals' and scale developers' perceptionsof the relevant domains for inclusion.5 How-ever, the only valid perspective for judging theitems of relevance in scale development is thatof the person affected by the condition.

Several meanings have been imputed to theterm "quality of life", ranging from individualfulfilment to the ability to lead a "normal" lifeto the satisfaction of human needs (physical,psychological, and social) (see reference5 forreview). Quality of life is also dependent uponthe individual's subjective perception of hisachievement, which most measurement scalesfail to encompass in their efforts to limit them-selves to domains such as functioning (for ex-ample, domestic, return to work), the degreeand quality of social and community inter-action, psychological wellbeing, somaticsensation (for example, pain), symptoms, ad-justment, coping, and life satisfaction.67 Philo-sophers, social scientists, and social

Centre for HealthInformatics andMultiprofessionalEducation, UniversityCollege LondonMedical School(WhittingtonCampus), WhittingtonHospital, 4th floor,Archway Wing,Highgate Hill, LondonN19 SNFA BowlingCorrespondence to:Dr A Bowling.Accepted for publicationOctober 1995

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gerontologists have a long history of con-centrating on happiness, life satisfaction, in-dependence, and control, and on theidentification of the "good life" (see reference5for review). This has led to the widespreaddefinition of quality of life in social science asthe extent to which pleasure and satisfactionhave been obtained.89 While mental health pro-fessionals have developed their concepts ofquality of life from this body of knowledge,particularly from the research on social in-dicators,' 01' rarely have investigators concernedwith the measurement of quality of life in re-lation to physical conditions done so.

Despite these gaps, subjective indicatorsbased on self ratings of mental, psychological,and physical wellbeing are increasingly popularamong investigators due to the recognition ofthe importance of how individuals feel, ratherthan what statistics imply they ought to feel.Promising research on health related quality oflife has involved the application of the tech-niques of human judgement analysis to assesshealth related quality of life, which is a novelmethod of measuring this concept from theperspective ofthe individual. 12-5 With this tech-nique respondents are asked to list the fiveareas of life ("cues") that they judge to be themost important to their overall quality of life(the technique is known as the schedule for theevaluation of quality of life - SEIQoL). Openended questions are used to elicit the relevantcues, then techniques are used of deriving rel-ative weights of importance of each area. Sim-pler but similarly hermaneutic approaches tomeasuring disease specific quality of life wereadopted by Guyatt et al in their developmentof quality of life scales for people with boweldisorders, respiratory disease, and heart dis-ease. With their scales, respondents are asked tolist activities that are affected by their condition,and then to specify which are the most im-portant in their day to day lives.""'8The research presented here aimed to begin

to build up a theoretically useful body of know-ledge, based on population norms, for use inhealth services research on health related qual-ity of life (that is, in the evaluation of healthoutcomes of treatments).

Aims and methodsThe aims of the research were to provide popu-lation norms on the dimensions of life thatpeople perceive to be important in relation toquality of life and on how different conditionshave different impacts on people's lives.The hypothesis was that people with different

types of conditions will report different areasof life as being affected by these. While thishypothesis seems to be "common sense", itdoes have implications for the debate aboutthe design (that is, content) and use of genericand disease specific quality of life measurementscales.The study design was an interview survey

which was based on a target random sample of2000 people in Great Britain taken by theOffice of Population Censuses and Surveys(OPCS) for their monthly ominibus survey at

the end of 1994. The sampling frame for theOPCS omnibus survey was the postcode ad-dress file of "small users", which includes allprivate household addresses, stratified by re-gion, the proportion ofhouseholds renting fromlocal authorities, and the proportion in whichthe head of household is in socioeconomicgroups 1-5 or 13 (that is, professional, em-ployer, or manager). The postal sectors areselected with probability proportionate to size,and within each sector 30 addresses are selectedrandomly. If an address contains more thanone household, the interviewer uses a standardOPCS procedure to select just one householdrandomly. Within households with more thanone adult member, just one person aged 16 orover is selected for interview with the use ofrandom number tables. Because only onehousehold member is interviewed, people inhouseholds containing few adults have a betterchance of selection than those in householdswith many. A weighting factor is applied tocorrect for this unequal probability.

RESPONSEThe response rate to the survey was 77%.Fourteen per cent refused to take part, 1%were incapable of interview, and 8% were notcontactable. The total number of adults in-terviewed was 2033, and this resulted in 2031usable questionnaires.'9 The effects of theweighting procedure and the method of sam-pling are discussed elsewhere.20 In the analyses,percentages are rounded to the nearest wholenumber, from 0 5 upwards and from thatdownwards. Attention is drawn to differencesthat are statistically significant using x2 tests,at least at the 0-05 level of confidence.

QUESTIONNAIRE DESIGNGiven the lack of agreement about the com-ponents and definition of quality of life, theapproach taken in this research was her-meneutic and the aim was to ask respondentsthemselves simply about what was importantin their lives (positive and negative domains).This approach to measuring quality of lifewas based on the questions developed forSEIQoL'5 and disease specific quality of lifequestionnaires of Guyatt et all6'-8 which askpeople about what is important in their lives.

Respondents were first asked an open endedquestion about what were the most importantthings in their current lives (both good andbad). Respondents could mention as manyitems as they wished but only up to five werecoded. Respondents selected the code from ashowcard to represent the items mentioned,and both their free responses (which were com-pared with their coded responses by the re-searcher, to check consistency) and selectedcodes were recorded. The items on the show-card were chosen after analysis of the itemsmentioned by the respondents to the surveysof O'Boyle et al,"'3 and responses to othersurveys of quality of life. Items which did notfit the pre-codes were listed and coded by theinterviewers under "other"; these were analysedby the researcher and an extension to the coding

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frame was designed to enable the "other" codesto be re-coded later by OPCS coders. Re-spondents were then asked to place the itemsmentioned in rank order of importance. Bothrespondents' selected codes of life areas andtheir free responses (which were later codedback in the office) were analysed and compared.Then subjects were asked to rate their currentstatus for each item mentioned against a cat-egorical scale, labelled at each extremity "asgood as could possibly be" and "as bad ascould possibly be". Respondents were thenasked to rate their overall life on a similarlylabelled categorical scale.The self rated health status and reported

longstanding illness questions were based onthose used in OPCS surveys.2-24 Respondentswere asked the standard OPCS question: "Doyou have any longstanding illness, disability orinfirmity? By longstanding I mean anythingthat has troubled you over a period of time orthat is likely to affect you over a period of time?"Respondents who said "yes" were asked whatthe condition was (and later about the con-dition that had most affected their life as awhole, over the last 12 months, if more thanone was reported), and whether it "limits youractivities in any way?"

Respondents who reported any limiting long-standing illness, disability, or infirmity werenext also asked to define and rate the mostimportant effects of this on their lives using thesame techniques. Those who reported morethan one were asked to select the conditionwhich had most affected their life as a wholeover the last 12 months for the next questionson how their lives had been affected ("thinkingabout your (condition . . .), what would yousay are the most important things in your lifewhich have been affected by this?"). Re-spondents' free responses were recorded by theinterviewer (and these were coded later in theoffice); respondents were then also asked toselect codes themselves from a showcard torepresent the things they had mentioned, andthen list them in priority order of importance.Respondents' own coding oftheir free responsechoices and the office coding of their recordedresponses were analysed and compared. Themethod was an adapted (simple) version of themethod employed by O'Boyle et all5 in relationto SEIQoL. SEIQoL itself produces con-tinuous rather than categorical data and in-volves the drawing of bar charts during theinterview to represent the respondent's pri-orities. This method was too complex to beused in a large national survey (the OPCSomnibus survey uses 100 interviewers who arebriefed by post, necessitating the use of con-ventional, standardised questionnaire design).Data were analysed in relation to age, sex,

marital status, health status, longstanding ill-ness, disability or infirmity (and type, wherenumbers permitted), housing tenure, socio-economic group, economic activity, income,social class, education, age left school, qual-ifications, and region. These were standardOPCS questions.2"-24 Attention has been drawnto differences which were statistically signi-ficant, using x% test, at least at the p

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than in the 1992 general household survey(GHS) (personal communication, Office ofPopulation Censuses and Surveys, GHS Unit).People who assessed their health as "not good"were most likely to mention effects on the ownhealth as the first most important thing in lifegenerally (36%, in comparison with 20-24%of others), and they were least likely to mentionthe health of (close) others (10% in comparisonwith 20-23% of others).A relatively high proportion (40%) reported

a longstanding illness, disability, or infirmity,and 60% of these reported that it limited theiractivities in some way. The proportion whoreported a longstanding illness was similar tothe proportions reported in the 1991 and 1992OPCS health survey2324 and, as with the latter,the proportion was 4% higher than the pro-portion reporting this in the GHS.2122 In re-lation to this difference, OPCS reported thatpeople might have been more likely to reportan illness in the health survey because theywere taking part in a health survey rather thana general survey.24 In the case of the presentstudy, although health was not mentioned untilhealth status and longstanding illness wereasked about later in the questionnaire (that is,after the generic questions about the importantthings in life), it is possible that respondentswere more sensitised to health as they knewthat the set of questions was asked on behalf of"St Bartholomew's Hospital Medical College",where the author was then based.The interviewer coded the number of long-

standing illnesses/disabilities/infirmities (LSI)reported; 27% of all respondents reported justone and 13% reported multiple conditions.The conditions mentioned were coded in theoffice by OPCS, using the coding frame de-veloped for the OPCS health survey. The con-ditions most frequently mentioned by the 40%were hay fever (15%), back problems (11%),hypertension (6%), and musculoskeletal prob-lems (usually arthritis) (6%). These conditionswere also coded into more global categories:the conditions that were most frequently men-tioned (by the 40%) as affecting respondents'lives were diseases of the respiratory system(29%), diseases of the musculoskeletal system(17%), and diseases ofthe heart and circulatorysystem (cardiovascular) (14%). Various otherconditions were mentioned by between

Quality of life 153

Table JA Type of longstanding illness or condition and areas of life most affected (with office coding of "other" category): first most important areaand all areas (priorities 1-5 +) mentionedArea affected Disorders of the respiratory system Disorders of the digestive organs* Disorders of the musculoskeletal system

First most important Mentioned at all First most important Mentioned at all First most important Mentioned at all(%) (1-5) (%) (%) (1-5) (%) (%) (1-5) (%)

Relationships with family/ 1 3 1 - 4 4relativesRelationships with other people - 4 - - - IHealth of someone close/ 1 1 - - -responsible forFinancial security/housing/ 2 2 - - 1 4standards of livingConditions of work/job - 3 - - 3 3satisfactionAvailability of work/able to work 15 13 20 24 17 26Social life/leisure activities 2 33 9 16 24 36Pain 5 11 2 12 5 12Treatment side effects - - 2 5 -Tiredness/lack of energy 4 5 1 2 - 3Nausea/vomiting - - - -Other physical effects/symptoms 10 19 21 25 4 4Depression/worry/anxiety/ 3 8 5 9 - 6unhappinessMental confusion 1 1 - 2Other mental health problems - 1 - 2Effects on sex life - - - - 1 1Ability to get out about/stand/ 35 52 5 9 24 36walk/go out shoppingAbility to do housework/clean 8 17 2 2 5 14home/carry shopping/gardening/other similar activitiesOther restrictions on activities 4 8 2 9 11 17Dietary restrictions 1 1 25 40 - -Effects on appetite - - - - - -Other (eg, education, 3 4 4 6 1 2environment)No of respondents 173 173 41 41 114 114* Caution, small numbersSome cell numbers do not equal the total due to weighting and multiple response procedure for the 1-5 combination.

Table IB Type of longstanding illness or condition and areas of life most affected (with office coding of "other" category): first most important areaand all areas (priorities 1-5 +) mentionedArea affected Endocrine & Mental health Disorders of the Disorders of the heart &

metabolic disorders* disorders* nervous system* Eye complaints* circulatory system*

First most Mentioned First most Mentioned First most Mentioned First most Mentioned First most Mentionedimportant at all important at all important at all important at all important at all (1-5)(%/0) (1-5) (%) (%) (1-5) (%) (%) (1-5) (%/.) (%) (1-5) (%/o) (%) (%)

Relationships with family/relatives 6 6 14 19 - 4 - 4 1Relationships with other people - - 9 20 3 3 1 3 - 1Health of someone close/responsible for - - - - - - - - 1 1Financial security/housing/standards of 2 12 7 19 - - - 2 7livingConditions at work/job satisfaction - - 3 7 1 1 - - - -Availability of work/able to work - - 21 36 27 42 12 15 15 17Social life/leisure activities - 12 19 31 6 24 7 20 2 26Pain - 5 - - - 3 9 12 5 7Treatment side effects 2 17 - - - 3 - 1Tiredness/lack of energy 11 18 - 7 - 7 5 7 2 6Nausea/vomiting - - - 3 3 - -Other physical effects/symptoms 15 18 - 2 13 21 8 26 12 24Depression/worry/anxiety/unhappiness 8 17 17 27 17 14 3 9 6 18Mental confusion 3 3 - 2 - 3 - -Other mental health problems - - - - 3 7 - - 3 5Effects on sex life - - - 5 - - - - -Ability to get out about/stand/walk/go out 9 15 5 15 20 21 30 45 33 42shoppingAbility to do housework/clean home/carry 2 2 2 5 1 13 7 28 7 18shopping/gardening/other similar activitiesOther restrictions on activities - 6 - - 10 13 18 26 9 15Dietary restrictions 38 48 - - - 3 - 4 1 3Effects on appetite - - - 5 - - 3 - 1Other (eg, education, environment) 5 6 3 3 7 7 - 3No of respondents 33 33 30 30 36 36 38 38 75 75* Caution small numbersSome cell numbers do not equal the total due to weighting and multiple response procedure for the 1-5 combination.

ness/condition on respondents' lives, and allareas combined into an overall frequency withwhich the area was mentioned. The conditionswhich were excluded for presentation in Table1 include neoplasms, ear complaints, genito-urinary conditions, skin conditions, infections,and disorders of the blood where base numberswere 15 or less.The most important areas of life mentioned

in relation to the effects of specific conditionswere different to those mentioned generically.Table 1 shows consistency, on the whole, be-

tween the first most important area of life affec-ted by the condition, and the most frequentlymentioned area (1-5 priority ranks combined).For example, it shows that people with mentalhealth problems and disorders of the nervoussystem were all most likely to rate availabilityof work/able to work as thefirst most importantarea affected and the most frequently men-tioned area. People with eye conditions, cardio-vascular disease, respiratory disease, anddisorders of the musculoskeletal system wereall most likely to mention ability to get out and

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about as the first most important area and itwas the most frequently mentioned area (1-5combined). Respondents with digestive andendocrine disorders were most likely to men-tion dietary restrictions as the first most im-portant effect, and as the most frequentlymentioned effect (1-5).

In some cases the different distributions offrequencies with which areas were mentionedas either first most important or mentionedat all (1-5) leads to differences in terms ofmagnitude. For example, in relation to res-piratory disease and ability to get out and about(35% first most important:52% mentioned atall (1-5)), and cardiovascular disease and abil-ity to get out and about (33%:42%), and inrelation to musculoskeletal conditions andeffects on social life (24%:36%, respectively)and respiratory conditions and effects on sociallife (2%:33%). The base numbers of peoplewith genito-urinary conditions (n 15), earcomplaints (n =13), neoplasms (n = 11), skinconditions (n = 5), diseases of the blood andrelated organs (n = 3), and infectious and para-sitic conditions (n = 2) are too small for in-terpretation.

Summary and discussionThe research presented here highlights the needfor more sensitive measurement of health re-lated quality of life. Respondents were mostlikely to select as the first most important thingin their lives relationships with family or rel-atives, followed by their own health, the healthof another (close) person, and finances/stand-ard of living/housing. When priority rankedareas 1-5 were combined, the most frequentlymentioned area of life was finances/standard ofliving/housing, followed by relationships withfamily and relatives, own health, the health ofclose others, and social life/leisure activities.The most common, freely mentionedfirst mostimportant effects of longstanding illness onrespondents lives were different to those men-tioned generically. In relation to longstandingillness they were (in order of frequency), abilityto get out and about/stand/walk/go out shop-ping, being able to work/find a job and effectson social life/leisure activities (office codingfrom verbatim responses recorded on the ques-tionnaire). When priority ranks 1-5 are com-bined, the most frequently mentioned area oflife affected was also ability to get out andabout/stand/walk/go out shopping, but fol-lowed, in a different order, by social life/leisureactivities, and availability of work/ability towork.

This research also supports the current trendof developing disease specific health relatedquality of life questionnaires rather than usinggeneric scales. For example, taking just the firstmost important area of life affected by thecondition, respondents reporting mental healthproblems and diseases of the nervous systemas their longstanding condition were most likelyto prioritise the availability of work/ability towork as the first most important area of lifeaffected; respondents with eye problems, withcardiovascular, respiratory and musculoskeletal

disorders, were most likely to report the abilityto get out and about as the first most importantarea of life affected; and respondents with en-docrine and with digestive disorders were mostlikely to report dietary restrictions as the firstmost important area of life affected.

Previous analysis of the domains included inthe most popularly used health status scales,which are used to measure health related qual-ity of life, showed several items ranked asimportant by the public (generically) to bemissing.25 Health related quality of life ques-tionnaires also need to be sensitive to the typeof respondents (for example, in relation to ageand sex) and to their condition. O'Boyle et al.'5using SEIQoL, reported variation in the weightsdifferent groups of respondents attached to thedomains of importance mentioned, and alsovariations with different treatment and recoveryperiods. This research, together with the resultsreported here, support the need for hermeneuticapproaches to measurement. The developmentof SEIQoL'213 and Guyatt et als respondentbased, disease specific, questionnaires"6-18 showthat this approach can provide useable and valu-able data.Few disease specific or generic instruments

have been based on a model of quality of life,few scale developers have attempted to definethis concept, and few have been adequatelypatient based in their development. However,the public, and specific groups of patients,are the best judges of how medical conditionsadversely affect the quality of their lives. Thispaper provides an empirical contribution to themethodological issue of whether to use diseasespecific or generic quality of life scales, and,given that different domains of life are clearlyaffected by different types of conditions, theresults of this research strongly supports thedevelopment and use ofthe former. It is the firstempirical survey to demonstrate the inherentweakness of generic quality of life instrumentsin contrast to those which are disease specificor idiographic.

I thank Professor C A O'Boyle for helpful advice and willingnessto share information, the staff of OPCS for carrying out thesurvey and producing the results, Jack Eldridge and Jean Martinfor advice on questionnaire design, particularly Jack Eldridgeand Angie Osborne for the information on sampling and con-ducting the analyses, Morag Farquhar for helpful comments,and Lesley Marriott for typing the tables. Those who carriedout the original analysis and collection of the data hold noresponsibility for the further analysis and interpretation of them.Material from the OPCS omnibus survey, made availablethrough the OPCS, has been used with the permission of theController ofHM Stationery Office. The dataset is held on theESRC Data Archive at the University of Essex. The researchwas funded by the Economic and Social Research Council, andthe author is grateful for their support.

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