Job strain and cardiovascular mortality over long-term follow-up: a harmonized multicohort individual participant data meta-analysis

Objective: We aimed to assess the long-term association between high job strain (JS) and cardiovascular disease (CVD) mortality in cohorts from Italy, Germany, and the United States. Methods: We harmonized data from four cohort studies (MONICA Brianza, SEMM, MONICA/KORA, MIDUS), selecting employed participants aged 30-60 years and CVD-free at baseline. High JS was operationalized as high job demands and low job control. CVD mortality was ascertained over a median follow-up of >23 years. We estimated Cox models within each cohort; the main model was adjusted for sex, age, education, and occupational class. Additional analyses examined JS categories (low JS, active, passive, high JS), subgroups by sex and occupational classes, and person-time < and ≥65 years. Results were pooled using random-effects meta-analysis. Relevant published studies were identified for synthesis with our results. Results: Over 444 767 person-years, 842 CVD deaths occurred. High JS was associated with CVD mortality [hazard ratio (HR) 1.14, 95% confidence interval (CI) 1.01-1.27], with no evidence of heterogeneity. Results were consistent across JS categories, by sex (men: HR 1.15, 95% CI 1.07-1.23; women: HR 1.11, 95% CI 0.88-1.39), and across person-time <65 years (HR 1.24, 95% CI 0.91-1.67) and ≥65 years (HR 1.10, 95% CI 0.80-1.50). The association was stronger among manual workers (HR 1.25, 95% CI 0.84-1.86). Job demands appeared to contribute more than job control. Four published studies with comparable follow-up but heterogeneous study designs reported estimates consistent with our findings. Conclusions: High JS is a long-term predictor of CVD mortality, consistently across sexes and during both working age and after retirement. Workplace redesign to reduce job demands, particularly among manual workers, is warranted within a comprehensive prevention strategy.