Influences of social mobility, geographical mobility and changes in socio-spatial contexts on health outcomes

Paul Norman, University of Manchester and Paul Boyle, University of St Andrews

[Project number 30033]

A health divide between those who are better and worse off in society is well-established (e.g. Whitehead 1992; D'Arcy 1998) with a wealth of research pointing to socio-economic differences in morbidity and mortality (e.g. Davey Smith et al. 1997; Gordon et al. 1999; Graham 2000). The health gap across social classes has widened with evidence demonstrating that UK inequalities in life expectancy have increased since 1971 (Phillimore et al. 1994; Donkin et al. 2002).

Studies also identify geographical differences in health (e.g. Jones & Moon 1992; Britton 1990; Bryce et al. 1994). Such studies often examine the relationship between area-based deprivation measures and health outcomes focusing on mortality (e.g. Eames et al. 1993; Senior et al. 2000), morbidity (e.g. Boyle et al. 1999) and specific health outcomes (e.g. Crombie et al. 1989). The trend is also for increasing geographical inequality with those in the most deprived areas having increasingly poor health outcomes (Boyle et al. 2004; Rees et al. 2003; Shaw et al. 1999).

If we are attempting to identify whether social and geographical inequalities are increasing, alongside investigations of health-deprivation relationships, a fundamental problem is that many studies tend to be cross-sectional and cannot account for change over time. This is important because of:

1.) Social mobility. People's socio-demographic characteristics can change if they change their job circumstances and thus their social class;
2.) Geographical mobility (UK subnational migration). People change their locations through migration and, due to the selective nature of the migration process, this affects the counts of healthy and unhealthy persons in their origin and destination areas; and
3.) Changes in socio-spatial context. Locations themselves can change both through new house building and economic regeneration. As a result the aggregate characteristics of the community who live there will change with, for example, a change in unemployment rate in an area resulting in a different deprivation score.

These changes are inter-dependent and their combined influence on health outcomes must be investigated using linked longitudinal data. This study aims to consider the following research questions:
" Is the health of those moving up between a pair of social classes better than the health of those moving down between a pair of social classes?
" Does poor health lead to downward social mobility and vice versa for good health?
" Migrants are relatively healthy, but do some people's migration patterns differ because of poor health?
" Does social mobility have a greater effect on widening inequalities when combined with geographical mobility?
" Over time do people in good health accumulate in less deprived areas and people in poor health accumulate in more deprived areas?
" Are health inequalities between regions widening more than inequalities between deprivation categories?

No study to date has modelled health outcomes using longitudinal data whilst controlling for the parallel changes which can occur in people's lives through social mobility, geographical mobility and changes in the deprivation characteristics of the areas in which they live.

Just to study social mobility ignores the fact that people of similar characteristics tend to cluster together in space with this clustering likely to be driven by selective migration. Similarly, just to study health selective migration does not account for changes in people's other characteristics which may influence their health status. An area-based deprivation index is the aggregate of the characteristics of the people who live there. Any changes in the counts of persons of, for example, 'low social class' (an input variable to the Carstairs index) will affect the relative deprivation of an area. Many of these changes will be accounted for by both social mobility and selective migration.

Social mobility, geographical mobility and changes in socio-spatial context are highly inter-related and must be studied in tandem. Since transitions in and out of employment are relevant both to the recording of a person's social class and to personal and area deprivation, this too must be considered.

The applicants have previously used an extract from the LS for the 1971 to 1991 period to begin to address some of the issues outlined above (see Boyle et al. 2004; Norman et al. forthcoming; Boyle and Norman submitted) and others have examined the role of social mobility (e.g. Bartley and Plewis 1997) with this particular aspect ongoing (Bartley 2004). As it is linked longitudinal data and a large sample, the LS is the ideal data source through which to investigate these phenomena and their separate and combined influence on health outcomes, especially now that we have self-reported health in both the 1991 and 2001 Censuses.

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