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Socio-economic Inequalities in Cause-specific Mortality: A 16-year Follow-up Study

Canadian Journal of Public Health volume 104, pages e472–e478 (2013)Cite this article

Abstract

Objectives

To examine socio-economic inequalities in cause-specific mortality by examining the independent effects of education, occupation and income in a population-based study of working-age Canadian adults.

Methods

This is a secondary analysis of data from the 1991–2006 Canadian Census mortality and cancer follow-up study (n=2.7 million persons). For this analysis, the cohort was restricted to 2.3 million persons aged 25 to 64 at cohort inception, of whom 164,332 died during the follow-up period. Hazard ratios were calculated by educational attainment (4 levels), occupational skill (6 categories) and income adequacy (5 quintiles) for all-cause mortality and major causes of death. Models were run separately for men and women, controlled for multiple variables simultaneously, and some were stratified by 10-year age cohorts.

Results

The magnitude of socio-economic inequalities in mortality differed by indicator of socio-economic position (education, occupation, or income), age group, sex, and cause of death. Compared to age-adjusted models, hazard ratios were attenuated but remained significant in models that adjusted for both age and all three indicators of socio-economic position simultaneously. Socio-economic inequalities in mortality were evident for most of the major causes of death examined.

Conclusion

This study demonstrates that education, occupation and income were each independently associated with mortality and were not simply proxies for each other. When evaluating socio-economic inequalities in mortality, it is important to use different indicators of socio-economic position to provide a more complete picture.

Résumé

Objectifs

Étudier les inégalités socioéconomiques influant sur la mortalité selon la cause en examinant les effets indépendants du niveau de scolarité, de la profession et du revenu dans le cadre d’une étude basée sur la population d’adultes canadiens en âge de travailler.

Méthode

Il s’agit d’une analyse secondaire des données de l’étude canadienne de suivi de la mortalité et du cancer selon le recensement, 1991–2006 (n=2,7 millions de personnes). Pour cette analyse, on a créé une cohorte limitée à 2,3 millions de personnes âgées de 25 à 64 ans, dont 164 332 sont décédées durant la période de suivi. Les rapports des risques ont été calculés pour toutes les causes confondues et les causes principales de décès, selon le niveau de scolarité (4 niveaux), les compétences professionnelles (6 catégories) et la suffisance du revenu (5 quintiles). On a exécuté des modèles séparément pour les hommes et les femmes, en tenant compte de variables multiples simultanément, et certains ont été stratifiés par cohortes d’âge de 10 ans.

Résultats

L’ampleur des inégalités socioéconomiques influant sur la mortalité variait selon l’indicateur de la situation socioéconomique (niveau de scolarité, profession ou revenu), le groupe d’âge, le sexe et la cause de décès. Comparativement aux modèles ajustés en fonction de l’âge, les rapports des risques étaient atténués, mais demeuraient importants dans les modèles ajustés en fonction de l’âge et des trois indicateurs de la situation socioéconomique simultanément. Des inégalités socioéconomiques influant sur la mortalité ont été observées pour la plupart des causes principales de décès examinées.

Conclusion

Cette étude démontre que le niveau de scolarité, la profession et le revenu étaient tous associés de manière indépendante à la mortalité et n’étaient pas simplement des variables de substitution l’une pour l’autre. Dans le cadre de l’étude des inégalités socioéconomiques influant sur la mortalité, il est important d’utiliser différents indicateurs de la situation socioéconomique afin de brosser un tableau plus complet.

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Author information

Affiliations

  1. Health Analysis Division, Statistics Canada, RHC-24Q, 100 Tunney’s Pasture Driveway, Ottawa, ON, K1A 0T6, Canada

    Michael Tjepkema MPH

  2. Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, ON, Canada

    Russell Wilkins MUrb

  3. Public Health Agency of Canada, Ottawa, ON, Canada

    Andrea Long MA

Authors
  1. Michael Tjepkema MPH
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  2. Russell Wilkins MUrb
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  3. Andrea Long MA
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Corresponding author

Correspondence to Michael Tjepkema MPH.

Additional information

Acknowledgements: Funding for this analysis was provided by the Public Health Agency of Canada. Funding for the creation of the Canadian census mortality followup study was provided by the Canadian Population Health Initiative of the Canadian Institute for Health Information (original study), the Healthy Environment and Consumer Safety Branch of Health Canada (study extensions), and the Health Analysis Division of Statistics Canada. Finally, the authors acknowledge the key importance of Canada’s provincial and territorial registrars of vital statistics, who furnish the death data for the Canadian Mortality Database.

Conflict of Interest: None to declare.

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Tjepkema, M., Wilkins, R. & Long, A. Socio-economic Inequalities in Cause-specific Mortality: A 16-year Follow-up Study. Can J Public Health 104, e472–e478 (2013). https://doi.org/10.17269/cjph.104.4075

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  • DOI: https://doi.org/10.17269/cjph.104.4075

Key words

  • Canada/epidemiology
  • socioeconomic factors
  • mortality

Mots clés

  • Canada/épidémiologie
  • facteurs socioéconomiques
  • mortalité