Labour market income inequality and mortality in North American metropolitan areas
- 1Health Analysis and Measurement Group, Statistics Canada, Ottawa, Canada
- 2Department of Geography, McGill University, Associate, Health Analysis and Measurement Group, Statistics Canada, Montreal, Canada
- 3Statistics Canada
- 4Department of Community Health Sciences, University of Calgary, Canada
- 5School of Public Health, University of Michigan, Ann Arbor, USA
- Correspondence to: Claudia Sanmartin Health Analysis and Measurement Group, Statistics Canada, RH Coats Bldg, 24th Floor Section R, Ottawa, Canada K1A 0T6; claudia.sanmartinstatcan.ca
- Accepted 5 March 2003
Abstract
Objective: To investigate relations between labour market income inequality and mortality in North American metropolitan areas.
Methods: An ecological cross sectional study of relations between income inequality and working age (25–64 years) mortality in 53 Canadian (1991) and 282 US (1990) metropolitan areas using four measures of income inequality. Two labour market income concepts were used: labour market income for households with non-trivial attachment to the labour market and labour market income for all households, including those with zero and negative incomes. Relations were assessed with weighted and unweighted bivariate and multiple regression analyses.
Results: US metropolitan areas were more unequal than their Canadian counterparts, across inequality measures and income concepts. The association between labour market income inequality and working age mortality was robust in the US to both the inequality measure and income concept, but the association was inconsistent in Canada. Three of four inequality measures were significantly related to mortality in Canada when households with zero and negative incomes were included. In North American models, increases in earnings inequality were associated with hypothetical increases in working age mortality rates of between 23 and 33 deaths per 100 000, even after adjustment for median metropolitan incomes.
Conclusions: This analysis of labour market inequality provides more evidence regarding the robust nature of the relation between income inequality and mortality in the US. It also provides a more refined understanding of the nature of the relation in Canada, pointing to the role of unemployment in generating Canadian metropolitan level health inequalities.
Footnotes
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Funding: the research is funded by a grant from the Canadian Population Health Initiative (CPHI). CS is supported by a Statistics Canada postdoctoral award. NAR has a New Investigator salary award from the Canadian Institutes of Health Research (CIHR). JRD also has a New Investigator award from CIHR and salary support from the Alberta Heritage Foundation for Medical Research (AHFMR). JL is supported by a Robert Wood Johnson Health Investigator Award.
