Overqualification and risk of all-cause and cardiovascular mortality: evidence from the Canadian Census Mortality Follow-up Study (1991-2001).

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.