Abstract
Objectives
To evaluate whether education, occupation and overqualification (defined as having a level of educational attainment higher than the skill level required for an occupation) are associated with risk of all-cause and cardiovascular disease (CVD) mortality.
Method
A prospective study of the association between overqualification and all-cause and CVD mortality was undertaken in the Canadian Census Mortality Follow-up study (1991–2001), a 15% sample of Canadian adults who completed the 1991 census long-form questionnaire (n=1,091,800, 39% women, baseline age 35–64 years). Education, occupation and all confounders (age, income adequacy, marital status, years since immigration, ethnicity, Aboriginal origins, province of residence, and community size) were measured at study baseline, with subsequent follow-up for mortality.
Results
Sex-specific age-adjusted Cox proportional hazards models showed an inverse association between education and all-cause mortality (women: hazard ratio (HR)=1.55, 95% confidence interval (CI): 1.45-1.66; men: HR=1.94, 95% CI: 1.87-2.01, for <high school vs. university degree). In addition, age-adjusted occupation was inversely associated with all-cause mortality (women: HR=1.42, 95% CI: 1.32-1.53; men: HR=1.86, 95% CI: 1.78-1.95, for unskilled vs. professional occupation). Similar social gradients were observed for CVD mortality. Overqualification was not associated with risk of all-cause or CVD mortality, demonstrated by non-statistically significant interaction terms between education and occupation.
Conclusions
Increasingly, Canadians are pursuing high levels of education; however, the occupational distribution in the labour market has not changed to the same extent. Results from this study suggest that the resulting increase in workers who are overqualified for their occupation will not lead to increased all-cause or CVD mortality.
Key words: Canada/epidemiology, socioeconomic factors, mortality, cardiovascular diseases
Résumé
Objectifs
Déterminer si l’instruction, la profession et la surqualification (définie comme le fait d’avoir un niveau d’instruction supérieur au niveau de compétence exigé pour une profession) sont associées au risque de mortalité toutes causes confondues et de mortalité due aux maladies cardiovasculaires (MCV).
Méthode
Une étude prospective de l’association entre la surqualification et la mortalité toutes causes confondues et due aux MCV a été menée dans l’Étude canadienne de suivi de la mortalité selon le recensement (1991-2001), un échantillon de 15 % des Canadiens d’âge adulte ayant rempli le questionnaire complet du Recensement de 1991 (n=1 091 800, 39 % de femmes, 35 à 64 ans au début de l’étude). L’instruction, la profession et tous les facteurs confusionnels (âge, niveau adéquat du revenu, état matrimonial, années depuis l’immigration, ethnicité, origines autochtones, province de résidence et taille de la communauté) ont été mesurés au début de l’étude, et un suivi ultérieur a été fait pour la mortalité.
Résultats
Des modèles des risques proportionnels de Cox rajustés selon l’âge et le sexe ont montré une association inverse entre l’instruction et la mortalité toutes causes confondues (femmes: coefficient de danger (CD)=1,55, intervalle de confiance (IC) de 95 %: 1,45-1,66; hommes: CD=1,94, IC de 95 %: 1,87-2,01, <diplôme d’études secondaires c. diplôme universitaire). De plus, la profession rajustée selon l’âge était inversement associée à la mortalité toutes causes confondues (femmes: CD=1,42, IC de 95 %: 1,32-1,53; hommes: CD=1,86, IC de 95 %: 1,78-1,95, main-d’œuvre non qualifiée c. main-d’œuvre professionnelle). Des gradients sociaux semblables ont été observés pour la mortalité due aux MCV. La surqualification n’était associée ni au risque de mortalité toutes causes confondues, ni au risque de mortalité due aux MCV, comme en témoignent les paramètres d’interaction non significatifs entre l’instruction et la profession.
Conclusions
De plus en plus, les Canadiens font des études poussées, mais la répartition professionnelle sur le marché du travail n’a pas changé dans la même proportion. D’après les résultats de notre étude, l’augmentation des travailleurs surqualifiés pour leur profession n’entraînera pas de hausse de la mortalité toutes causes confondues ni de la mortalité due aux MCV.
Mots clés: Canada/épidémiologie, facteurs socioéconomiques, mortalité, maladies cardiovasculaires
Footnotes
Acknowledgement: The authors acknowledge the leadership of Dr. Michael Wolfson in the creation of the Canadian Census Mortality Follow-up Study.
Sources of funding: Funding for this research was provided by the Canadian Population Health Initiative of the Canadian Institute for Health Information, the Canadian Institutes of Health Research, and the Research Advisory Council of the Ontario Workplace Safety and Insurance Board. Brendan Smith is supported through a Frederick Banting and Charles Best Canada Graduate Scholarships Doctoral Award, Canadian Institutes of Health Research. Peter Smith is supported by a New Investigator Award from the Canadian Institutes of Health Research.
Conflict of Interest: None to declare.
References
- 1.Kaplan GA, Keil JE. Socioeconomic factors and cardiovascular disease: A review of the literature. Circulation. 1993;88:1973–98. doi: 10.1161/01.CIR.88.4.1973. [DOI] [PubMed] [Google Scholar]
- 2.Galobardes B, Shaw M, Lawlor DA, Lynch JW, Davey Smith G. Indicators of socioeconomic position (part 1) J Epidemiol Community Health. 2006;60(1):7–12. doi: 10.1136/jech.2004.023531. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Kuh D, Ben-Shlomo Y, Lynch J, Hallqvist J, Power C. Life course epidemiology. J Epidemiol Community Health. 2003;57(10):778–83. doi: 10.1136/jech.57.10.778. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Krieger N, Williams DR, Moss NE. Measuring social class in US public health research: Concepts, methodologies, and guidelines. Annu Rev Public Health. 1997;18:341–78. doi: 10.1146/annurev.publhealth.18.1.341. [DOI] [PubMed] [Google Scholar]
- 5.Davey Smith G, Hart C, Hole D, MacKinnon P, Gillis C, Watt G, et al. Education and occupational social class: Which is the more important indicator of mortality risk? J Epidemiol Community Health. 1998;52(3):153–60. doi: 10.1136/jech.52.3.153. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Singh-Manoux A, Clarke P, Marmot M. Multiple measures of socio-economic position and psychosocial health: Proximal and distal measures. Int J Epidemiol. 2002;31(6):1192–99. doi: 10.1093/ije/31.6.1192. [DOI] [PubMed] [Google Scholar]
- 7.Dressler WW. Social consistency and psychological distress. J Health Soc Behav. 1988;29(1):79–91. doi: 10.2307/2137182. [DOI] [PubMed] [Google Scholar]
- 8.McEwen BS. Protective and damaging effects of stress mediators. N Engl J Med. 1998;338(3):171–79. doi: 10.1056/NEJM199801153380307. [DOI] [PubMed] [Google Scholar]
- 9.Gilmore J. The 2008 Canadian Immigrant Labour Market: Analysis of Quality of Employment. Ottawa, ON: Statistics Canada; 2009. [Google Scholar]
- 10.Li C, Gervais G, Duval A. The Dynamics of Overqualification: Canada’s Underemployed University Graduates. Ottawa: Statistics Canada; 2006. [Google Scholar]
- 11.Peter R, Gassler H, Geyer S. Socioeconomic status, status inconsistency and risk of ischaemic heart disease: A prospective study among members of a statutory health insurance company. J Epidemiol Community Health. 2007;61(7):605–11. doi: 10.1136/jech.2006.047340. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Faresjö T, Svärdsudd K, Tibblin G. The concept of status incongruence revisited: A 22-year follow-up of mortality for middle-aged men. Scand J Soc Med. 1997;25(1):28–32. doi: 10.1177/140349489702500107. [DOI] [PubMed] [Google Scholar]
- 13.Smith P, Frank J. When aspirations and achievements don’t meet. A longitudinal examination of the differential effect of education and occupational attainment on declines in self-rated health among Canadian labour force participants. Int J Epidemiol. 2005;34(4):827–34. doi: 10.1093/ije/dyi047. [DOI] [PubMed] [Google Scholar]
- 14.Lundberg J, Kristenson M, Starrin B. Status incongruence revisited: Associations with shame and mental wellbeing. Sociol Health Illn. 2009;31(4):478–93. doi: 10.1111/j.1467-9566.2008.01148.x. [DOI] [PubMed] [Google Scholar]
- 15.Braig S, Peter R, Nagel G, Hermann S, Rohrmann S, Linseisen J. The impact of social status inconsistency on cardiovascular risk factors, myocardial infarction and stroke in the EPIC-Heidelberg cohort. BMC Public Health. 2011;11:104. doi: 10.1186/1471-2458-11-104. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Horan PM, Gray BH. Status inconsistency, mobility and coronary heart disease. J Health Soc Behav. 1974;15(4):300–10. doi: 10.2307/2137090. [DOI] [PubMed] [Google Scholar]
- 17.Statistics Canada. National Occupational Classification for Statistics 2006. Ottawa: Statistics Canada; 2007. [Google Scholar]
- 18.Zhang X. Status inconsistency revisited: An improved statistical model. Eur Sociol Rev. 2008;24(2):155–68. doi: 10.1093/esr/jcm048. [DOI] [Google Scholar]
- 19.Wilkins R, Tjepkema M, Mustard C, Choiniere R. The Canadian census mortality follow-up study, 1991 through 2001. Health Rep. 2008;19(3):25–43. [PubMed] [Google Scholar]
- 20.World Health Organization. Manual of the International Statistical Classification of Diseases, Injuries and Causes of Death. Geneva, Switzerland: WHO; 1977. [Google Scholar]
- 21.World Health Organization. International Statistical Classification of Diseases and Related Health Problems. Geneva: WHO; 1992. [Google Scholar]
- 22.Statistics Canada. 1991 Census Dictionary (Catalogue 92-301E) Ottawa: Supply and Services Canada; 1992. [Google Scholar]
- 23.Winkleby MA, Jatulis DE, Frank E, Fortmann SP. Socioeconomic status and health: How education, income, and occupation contribute to risk factors for cardiovascular disease. Am J Public Health. 1992;82(6):816–20. doi: 10.2105/AJPH.82.6.816. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Mackenbach JP, Bos V, Andersen O, Cardano M, Costa G, Harding S, et al. Widening socioeconomic inequalities in mortality in six Western European countries. Int J Epidemiol. 2003;32(5):830–37. doi: 10.1093/ije/dyg209. [DOI] [PubMed] [Google Scholar]
- 25.Stringhini S, Sabia S, Shipley M, Brunner E, Nabi H, Kivimaki M, et al. Association of socioeconomic position with health behaviors and mortality. JAMA. 2010;303(12):1159–66. doi: 10.1001/jama.2010.297. [DOI] [PMC free article] [PubMed] [Google Scholar]