Short ReportHealth inequalities in urban and rural Canada: Comparing inequalities in survival according to an individual and area-based deprivation index☆
Introduction
Social inequalities in health are well known in urban Canada. Many studies reveal huge discrepancies related to income or deprivation in life expectancy, mortality, hospitalization and self-reported health (CIHI, 2008; James et al., 2007; CPHI, 2006b; Ross, 2004; Choinière, 2002). Such inequalities are also present in rural Canada (Pampalon et al., 2006; CPHI, 2006a; Mitura and Bollman, 2003). Here, marked differences are found between areas bordering urban centres and the remote hinterland, the latter exhibiting poor scores on health issues and socio-economic conditions. Despite these studies, it is not clear whether social inequalities in health are greater in urban than rural Canada. In studies comparing urban and rural areas, urban areas are often considered as a whole (all urban areas combined) and when variations within urban and rural areas are presented, social inequalities are measured differently. In urban areas, social inequalities are generally measured through neighbourhood income whereas in rural areas distance or remoteness from urban centres is mainly considered.
Recently, in Québec and in Canada, as a whole, inequalities in mortality (0−74 years) in various geographic settings were compared on the basis of a similar area-based deprivation index (Pampalon et al., 2009b, Pampalon et al., 2008). Results show significantly greater rate ratios and rate differences in metropolitan areas and mid-size cities than in small towns and rural areas. Congruous observations were also made in England and Wales (Haynes and Gale, 2000; Senior et al., 2000). Here, inequalities in mortality (0−74 years) according to area-based deprivation indices (Townsend, Carstairs, Jarman) and single socio-economic measures are greatest in cities and smallest in rural areas, especially remote rural areas. However, when artifacts related to the use of small-area measures of deprivation are controlled for (i.e., different range of variation in deprivation, different small-area size), similar inequalities are found in urban and rural areas. For Haynes and Gale (2000), “the real variation is at the individual household level, within rural areas.”
In this study, we compare an individual and an area-based deprivation index in urban and rural Canada and draw on a broad Canadian census mortality follow-up survey (Wilkins et al., 2008). Preliminary results from that survey revealed that differences in life and disability-free life expectancies were underestimated when an area-based deprivation index was used, namely in small towns and rural areas (Pampalon et al., 2009a). In this study, we deepen our analysis by focusing specifically on four large geographic settings and subdividing rural areas in three separate zones. We also look at adult mortality, which is known to be closely related to social inequalities (WHO Commission on Social Determinants of Health, 2008), and develop the full potential of the survey by considering survival as the outcome measure. Finally, possible explanatory factors are explored.
Our hypothesis is that inequalities in survival are smaller in rural than urban areas when an area-based deprivation index is used but of equal magnitude when an individual version is retained. Our hypothesis holds not only for rural areas as a whole, but also for various zones within rural areas.
Section snippets
Urban and rural
The urban–rural continuum is first illustrated through four large geographic settings drawn from a new area classification (Statistics Canada, 2003): large census metropolitan areas (CMAs of Toronto, Montréal and Vancouver); other CMAs (population≥100,000); census agglomerations (CA: population≥10,000), hereafter “mid-size cities”; and small towns and rural areas (population<10,000). The last geographic setting is further subdivided into three metropolitan influenced zones (MIZs): strong MIZ,
Results
This study is based on a sample of approximately 2.6 million individuals aged 25–74 and 168,000 deaths (Table 1). Roughly 75% of these numbers concern urban Canada (CMAs and mid-size cities) and the remaining 25%, small towns and rural areas.
Survival, as estimated through hazard ratios of mortality, is closely related to deprivation in Canada (Table 2). In every geographic setting, the relative risk of mortality increases with deprivation whatever the version (individual or area-based) of the
Discussion
Both individual and area-based deprivation indices are associated with inequalities in survival in Canada. However, among the moderately and highly deprived population, the magnitude of these inequalities is clearly higher for the individual version of the index. Studies comparing both types of socioeconomic measures in relation to mortality show mixed results in the United States and Scotland (Rehkopf et al., 2006; Davey Smith and Hart, 1999; Greenwald et al., 1994) but higher discrepancies in
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Analyses in this paper are based on data from Statistics Canada. However, the opinions expressed do not represent the views of Statistics Canada.