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Census based self reported health measures: an examination of changes between the 1991 and 2001 censuses
Dermot O'Reilly and Michael Rosato, Queen's University Belfast
[Project number 30044]
Census based self reported health (SRH) measures are important indicators of morbidity both in individuals and at area level, and are used routinely in identifying social and health 'need' and in subsequent resource allocation. The 1991 Census for England and Wales contained a single question on limiting long-term illness (LLTI) - the extent of '.. health problems or handicap ..'. By 2001 the scope had extended to two questions: one on general health in the previous twelve months; and a modified LLTI question (on 'disability' rather than 'handicap').
Levels of self-reported ill-health are increasing. The Northern Ireland
census shows an increase in the proportion of reported LLTI from 11.1%
to 20.8% between 1991-2001; and, according to the GHS (GB) LLTI prevalence
has increased from 21% to 35% (1971-2000).
This is set within a secular trend of rising life expectancy and changes
in perception of what 'normal' health or well-being is at any point in
the lifecycle. Age, gender and pre-existing chronic illness all influence
SRH levels (1,2) and previous LS work has shown the importance of ethnicity
(3). There is also evidence of UK-wide regional variation (4), and it
has been suggested that changes to localised economic conditions can influence
employment chances and the flow of marginally ill people out of economic
activity into ill-health ('hidden unemployment') (5,6). Another question
raised by the 2001 questions relates to differences in scope: general
health asks about persisting problems, while LLTI is about limitations
on daily living. Research shows LLTI relates more to physical limitation
and less on mental and social wellbeing (these latter better reflected
in the general health question). Therefore, though they correlate highly
at both area and individual level, they may differ in relation to cause-specific
mortality.
We will examine implications of changes to the SRH questions over two
broad areas:
- Comparing LLTI at 2001 with its 1991 version - implications of the changed context and how this can be examined in relation to changing trends. We examine the degree of continuity in LLTI between censuses; transitions in associated demographic and socio-economic factors in relation to changing SRH status; and compare LLTI and short-term mortality after each census (1991-94, 2001-04).
- The relationship between LLTI and general health at the 2001 census and subsequent mortality (2001 to 2004) - using both all-cause and cause-specific mortality.
References:
1. Carr A, Gibson B, Robinson (2001) Measuring quality of life: Is quality
of life determined by expectations or experience? British Medical Journal
322; 1240-1243.
2. Daltroy L, Larson M, Eaton H, Phillips C, Liang M. Discrepancies between
self reported and observed physical function in the elderly: the influence
of response shift and other factors. Social Science and Medicine (1999);
48:549-1561.
3. Harding, S, Balarajan R. Limiting long-term illness among black Caribbeans,
black Africans, Indians, Pakistanis, Bangladeshis and Chinese born in
the UK Ethnicity & Health 2000; 5: 41-46.
4. O'Reilly D, Rosato M, Patterson C Self-reported health and mortality:
an analysis across the UK
(re)submitted to the British Medical Journal: 16/04/2005
5. Bartley M, Sacker A, Clarke P. Employment status, employment conditions,
and limiting illness: prospective evidence from the British household
panel survey 1991-2001 Journal of Epidemiology and Public Health (2004);
58; 501-506 doi: 10.1136/jech.2003.009878
6. Beatty C, Fothergill S, MacMillan R. A theory of employment, unemployment
and sickness. Regional Studies (2000). 34:617- 630.
The longitudinal study (LS), based on a continuing, representative, 1%
sample of the population of England and Wales, is a high quality multi-cohort
research database with ongoing linkage of routinely collected vital statistics
data with the census returns from 1971, 1981, 1991 and 2001. It therefore
provides a rare opportunity to track transitions in socio-demographic
and socio-economic circumstances between census points, and examine how
these relate to health outcomes. This project links with two others which
use the LS to examine different aspects of self-reported health in 1991
and 2001, and which have already been accepted by the research board (Harding
and Rosato: Social trajectories and long term illness among foreign-born
and UK-born ethnic minority groups). It is anticipated these will form
part of the analysis for a PhD thesis - the details of which are still
to be worked out, but which should begin in September 2005.