Typology of surveys in the UK which include questions on health problems or disability

1. General measures of health for use in Health Interview Surveys and Censuses: the UK experienceHoward Meltzer Social Survey Division, Office for National Statistics, LondonWashington City Group meeting, Ottawa9-10 January 2003

2. Typology of surveys in the UK which include questions on health problems or disability • Surveys which include a global measure of chronic ill health or disability (2/3 questions on limiting longstanding illness) • Surveys which include a module of questions on disability - look at relationship between disability and particular topic of survey (employment, housing, finances) • Surveys which have disability as their primary concern

3. Surveys in the UK which have included general measures of disability • Health Survey for England (HSE) • General Household Survey (GHS) • Health and Lifestyle Survey • Health Education Monitoring Survey (HEMS) • Psychiatric Morbidity Surveys (PMS) • National Child Development Survey • Physical Health of Prisoners • Family Resources Survey (FRS) • Censuses: 1991 and 2001

4. Surveys in the UK which have included a module of questions on disability • Labour Force Survey (LFS) • Focuses on limitation in type and kind of work • Opportunities for disabled people in labour market • Monitors the Disability Discrimination Act, 1995 • National Travel Survey (NTS) • Mobility, transport and travel • Use of cars or buses • English Housing Conditions Survey • Mobility, Activities of Daily Living, • Personal assistance, disability equipment, adaptations to the home

5. Surveys in the UK dedicated to the topic of disability • The 1971 OPCS Survey of “Handicapped and Impaired” in Great Britain • Adults • Private household and institutional population • The 1985 OPCS Surveys of Disability in Great Britain • Adults and children • Private household and institutional population • The 1996/7 follow up to the Family Resources Survey • Repeated the 1985 assessment schedule • Different methodology

6. Why are questions about general health included in surveys? • To control both the burden on respondents and the cost and complexity of surveys. A single question providing an indicator of general health is cheap and hopefully straightforward to interpret. • To derive a simple indicator (or small set of indicators) to subsume the detail which emerges when a person is questioned in depth about something as complex as his or her state of health. • To estimate the ‘burden of ill health’ in the population, where ‘ill health’ is defined as ‘that which requires input from the health services’.

7. Range of questions used in the UK • GHS (since 1971); HSE (since 1991) • Do you have any long-standing illness, disability or infirmity? By long-standing I mean anything that has troubled you over a period of time or that is likely to affect you over a period of time? • The GHS also asks a second question on limitation • Does this illness or disability (Do any of these illnesses or disabilities) limit your activities in any way?

8. Supplementary questions • Activities of Daily Living (OPCS, 1994) • Checklist of symptoms (Health Promotion Trust, 1987) • What is the matter with you? (GHS, 1988, 1989, 1994, 1996)

9. Census questions used in the UK • The 1991 Census used the following question: • Do you have any long-term illness, health problem or handicap which limits your daily activities or the work you can do? (Include problems which are due to old age) • The 2001 Census used a slightly different question: • Do you have any long-term illness, heath problem or disability which limits your daily activities or the work you can do? (Include problems which are due to old age)

10. Effect of question wording, question order and survey design (1) • Surveys which attempt to measure both limiting and non-limiting chronic illness with one question tend to produce lower overall estimates of prevalence than those which ask two separate questions. • Asking whether respondents ‘have’ a long-standing illness produces higher estimates than asking whether they ‘suffer’ from an illness; some people may answer ‘no’ to the latter on the grounds that they are not actually suffering (Goddard, 1990).

11. Effect of question wording, question order and survey design (2) • Asking whether an illness limits activities compared with ‘people of your age’ produces lower estimates than asking whether it limits them ‘in any way’; it is believed that elderly people in particular would say no because most of their contemporaries were as limited in their activities as they were (OPCS, 1975). • Using a checklist of symptoms stimulates reporting (Blaxter, 1987). It might produce overestimates of prevalence as informants who are not sure whether they have a condition might include themselves (Goddard, 1990).

12. Assessment of validity • Comparisons with standardised mortality rates • Higher rates among those with long term illness • Results of clinical examinations or doctors’ reports • Overall good agreement • Discrepancies not necessarily due to inaccurate self report • Problem may not have been brought to doctors’ attention • Medical records could be incomplete or inaccurate • Doctor may not have told patient of diagnosis • Lay descriptions may differ from those given by doctors

13. Caveats from validity studies • Elderly people regard limitations in their daily activities, particularly difficulties with eyesight and hearing, as a normal part of growing old, not as evidence of illness or disability (Martin et al. 1988). • Some people are more troubled by a certain kind of symptom than others, and that the need to limit activities will depend on what people usually do (Bennett et al. 1996) • Informants may also vary in the amount of information they choose to give or in their knowledge of the extent and nature of their ill-health (Blaxter, 1990). • Complaints most often missed are: anxiety and depression, varicose veins, migraine, haemorrhoids and ‘back trouble’

14. Empirical considerations • Identical questions do not produce identical estimates – although any differences tend to be small. • Differences can emerge for a number of reasons • Different approach to taking proxy information • Different non-response bias • Context: general versus specific health survey • Mode of administration (postal, face to face, telephone)

15. Longstanding illness by year (GHS)

16. Limiting longstanding illness by year (GHS)

17. Percentage reporting longstanding illness: GHS (1996) and HSE (1995) - Men

18. Percentage reporting longstanding illness: GHS (1996) and HSE (1995) - Women

19. Percentage reporting limiting longstanding illness: GHS (1996) and Omnibus (1995) - Men

20. Percentage reporting limiting longstanding illness: GHS (1996) and Omnibus (1995) - Women

21. Percentage reporting limiting longstanding illness: GHS (1991) and Census (1991) - Men

22. Percentage reporting limiting longstanding illness: GHS (1991) and Census (1991) - Women

23. Implications of the UK experience on the Minimum European Health Module (1) • Do you have any longstanding illness or health problem? (Yes/No) • No comparable question in the UK surveys • All UK surveys have the word “disability” or “infirmity” • The word “health problem” only occurs in the census.

24. Implications of the UK experience on the Minimum European Health Module (2) • For at least, the past six months, have you been limited in activities people usually do because of a health problem? (Yes/No) • Normally asked in reverse order, health than limitation • In population surveys, usually asked as two questions • The reference concept is always what the respondent usually does and not what “people usually do”.

25. Conclusions • Data from general health questions need to take account of differences in: • question wording, question order and context • mode of administration • population surveys as distinct from censuses • different responses by subgroups (age, gender, and social class) • how different conditions are rated (sight, hearing, mental health, access treatment) • reference group for assessing limitation

26. General measures of health for use in Health Interview Surveys and Censuses: the UK experienceHoward Meltzer Social Survey Division, Office for National Statistics, LondonWashington City Group meeting, Ottawa9-10 January 2003