Which influences the self-reporting of health: country of birth or country of residence? A British analysis using individual-level data Paul Norman 1, Paul Boyle 2 & Mark Brown 1 1 Centre for Census & Survey Research, University of Manchester 2 School of Geography and Geosciences, University of St Andrews Thanks to: ESRC RES Understanding Population Trends & Processes UK Census data via National Statistics Offices, ESRC, JISC & CCSR

Background 1991 & 2001 UK Censuses have self-reported health: limiting long-term illness (LLTI) Differences in LLTI found between England, Wales & Scotland in 1991, difference changed by 2001 Self-assessed health (e.g. LLTI) strongly correlates with: Mortality: all cause & cause specific Morbidity: general health, serious conditions, physical conditions rather than psychological Sickness benefit claims True for different countries, populations & question formulations

People from different cultural backgrounds: May report their health differently to other population sub- groups & from each other in different places at different times There is potential for self-assessment to be affected by subjective factors Differences in health between areas and population sub- groups perhaps due to varying interpretations of health (Bailis et al. 2003) In terms of LLTI, what constitutes a limiting and/or a long- term illness (Gooberman-Hill et al. 2003; Senior, 1998) Self-reported poor health is influenced by expectation and comparison. These may be culturally determined (Mitchell 2005)

UK Census LLTI research: Aggregate level – Various geographical scales (Boyle et al. 1999; Rees 1993/4; Senior 1998) Individual level microdata – Sample of Anonymised Records (SARs) (Boyle et al. 2001; Boyle et al. 2002; Borooah 1999; Gould & Jones 1996) – ONS Longitudinal Study (Bartley & Plewis 1997; Boyle et al. 2004; Harding 2002; Norman et al. 2005; Sloggett & Joshi 1998; Wiggins et al. 2002) Used as input to local health profiles

Where we live affects our health: (Macintyre et al. 2002; Tunstall et al. 2004) Environment most influential on health may not be the conditions contemporary with disease diagnosis or death (Boyle et al. 2002) Place of birth & childhood conditions affect later health (Curtis et al. 2004; Osmond et al. 1990; Kaplan & Salonen, 1991) Place of residence in middle age influential (Blane et al. 1996; Elford & Ben-Shlomo 1997) Relative importance of influences at different life stages found to vary by cause of death (Davey Smith et al. 1997) Differences because lag periods between contact with potential risk factors & subsequent health deterioration may vary by condition (Polissar 1980; Rogerson & Han 2002)

Migration process important: As we move between residential areas we experience different conditions and meet a range of people against whom we make comparisons when assessing our health Health differences between migrants and between geographical areas attributed to lifecourse disadvantage (Brimblecombe et al. 2000) Healthy people migrate into less deprived locations (Norman et al. 2005) Ill people may drift towards or becoming ‘stuck’ in deprived places (Boyle et al. 2002) International migrants tend to be relatively healthy (Bentham 1988) For non-migrants changing area characteristics affect health (Boyle et al. 2004)

Health differences between England, Scotland & Wales 1991 & 2001 Can we compare self-reported measures of illness between countries and culture over time? (Mitchell 2005) Is there something about being born in or living in England, Scotland or Wales which affects your health? For example: For the population resident in Wales, do those people born in Wales report different health to those born elsewhere? Do those who are Welsh born report their health differently when resident in another country?

Data UK Census Sample of Anonymised Records (SARs) for 1991 & 2001 Study population household residents in England, Scotland & Wales, all resident for at least one year 1991 SAR (2%) 1,116,181 individuals 2001 SAR (3%) 1,712,474 individuals Use of SARs enables variable definitions & modelling not possible with aggregate data Method Binary logistic regression Dependent variable: reporting of LLTI Models consistent for both 1991 & 2001

Method: Explanatory variables Age-group, Sex, Educational qualification, Ethnicity, Social Class, Access to car, Unemployment, Tenure Country of birth (CoB), Country of residence (CoR) (> 1 year in the country) ‘Country of birth by country of residence’ All variable definitions consistently defined 1991 & 2001 English in EnglandWelsh in EnglandRoW in England English in ScotlandWelsh in ScotlandRoW in Scotland English in WalesWelsh in WalesRoW in Wales Scottish in EnglandIrish in England RoW = Rest of the World Scottish in ScotlandIrish in Scotland Irish = Eire + NI Scottish in WalesIrish in Wales CoB = Nationality

1. Country of residence

2. Country of birth

3. Country of residence by country of birth

4. Country of birth & country of residence

Conclusions Odds of LLTI consistent with area models for 1991 (Rees 1993/4; Senior 1998) Change by 2001 also consistent with area research (Mitchell 2005) International migrants are relatively healthy (Bentham 1988) Is there a Welsh-born effect? Yes, those born in Wales tend to have higher LLTI odds wherever they live Is there a Wales effect? Yes, generally, whatever their country of birth, residents in Wales tend to have higher LLTI odds

Conclusions Is there a Scotland effect for the change? Yes. All countries of birth have higher odds in 2001 than in 1991 for residents in Scotland Is this due to a change in age structure? No. Scotland’s population is ageing similarly to England and Wales … Or a loss of healthy Rest of the World-born and gain of less healthy Welsh-born? No. The population structure by country of birth remains constant So are people in Scotland more willing to report LLTI or have environmental & socio-economic conditions become worse? We cannot tell from the SARs

Conclusions How does the influence of Country of Birth compare with the influence of Country of Residence? Country of birth has a significant effect of health, the relative difference between countries is consistent in 1991 & 2001 Country of residence has an additional and potentially variable effect on LLTI odds Findings consistent with early life influences persisting and with people experiencing different effects as their location & personal circumstances change How else can we compare self-reported measures of illness between British countries and culture over time? Transitions using the longitudinal data