Social inequalities, stressful work and non-fatal cardiovascular disease: follow-up findings from the CONSTANCES Study

BACKGROUND: Studies show that a disadvantaged socioeconomic position (SEP) and psychosocial stress at work are both independently associated with an increased risk of cardiovascular disease (CVD). But it is not clear if the effect of stress at work on CVD varies by SEP. METHODS: We used baseline and follow-up data from the French population-based cohort study CONSTANCES, including 48 383 employed women and men aged 30-70 years. Three SEP indicators (education, income, occupation), stressful psychosocial work as measured by effort-reward imbalance, pre-existing CVD and confounders were assessed at baseline, and incident non-fatal CVD events reported during annual follow-up (up to five follow-ups) were used as outcomes. The effect modification hypothesis was both investigated on an additive and multiplicative scale. RESULTS: SEP was inversely associated with CVD risk (eg, for low vs high income, OR 1.28 (95% CI 1.12 to 1.46)), and for all three components of stressful work CVD risks were significantly increased (eg, for effort-reward ratio OR 1.26 (95% CI 1.17 to 1.36)). Employees with a disadvantaged SEP showed moderately increased effect sizes of stressful work on CVD. However, no clear evidence of an effect modification was found. CONCLUSIONS: Disadvantaged SEP and stressful work contribute to higher CVD risk in this cohort. Despite moderately increased effect sizes for disadvantaged SEP groups, no evidence was found to support an effect modification hypothesis.