Background Mortality and morbidity have been shown to follow a ‘social gradient’ in Canada and many other countries around the world. Comparatively little, however, is known about whether ageing amplifies, diminishes or sustains socio-economic inequalities in health.
Methods Growth curve analysis of seven cycles of the Canadian National Population Health Survey (n=13 682) for adults aged 20 and older at baseline (1994/95). The outcome of interest is the Health Utilities Index Mark 3, a measure of health-related quality of life (HRQL). Models include the deceased so as not to present overly optimistic HRQL values. Socio-economic position is measured separately by household-size-adjusted income and highest level of education attained.
Results HRQL is consistently highest for the most affluent and the most highly educated men and women, and is lower, in turn, for middle and lower income and education groups. HRQL declines with age for both men and women. The rate of the decline in HRQL, however, was related neither to income nor to education for men, suggesting stability in the social gradient in HRQL over time for men. There was a sharper decline in HRQL for upper-middle and highest-income groups for women than for the poorest women.
Conclusion HRQL is graded by both income and education in Canadian men and women. The grading of HRQL by social position appears to be ‘set’ in early adulthood and is stable through mid- and later life.
- Health-related quality of life
- socio-economic status
- trajectory analysis
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Funding The study was supported in part by grant AG027129 from the National Institute on Ageing, National Institutes of Health and grant DK080277 from the National Institute of Diabetes and Digestive and Kidney Diseases. NAR gratefully acknowledges the support of a Research Scholar Career Award (#16290) from the Fonds de la Recherche en Santé du Québec.
Competing interests It should be noted that DF has a proprietary interest in Health Utilities Incorporated, Dundas, Ontario, Canada. Health Utilities Incorporated distributes copyrighted Health Utilities Index (HUI) materials and provides methodological advice on the use of HUI. It should also be noted that Health Utilities Incorporated received no payments for the use of the Health Utilities Index Mark 3 in the Statistics Canada National Population Health Survey reported in the paper.
Provenance and peer review Not commissioned; externally peer reviewed.
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