Increased job strain and cardiovascular disease mortality: a prospective cohort study in U.S. workers

Job strain is considered a potential risk factor of cardiovascular disease (CVD). Our objective was to examine prospective associations of job strain with CVD mortality using data from the national, population-based Mid-life in the United States (MIDUS) cohort study, while considering changes in job strain. Job strain measure was based on Demand-Control model at Wave 1 in 1995-1996 and Wave 2 in 2004-2006, and CVD mortality data through 2018 were retrieved through linkage to the National Death Index (NDI). Cox proportional hazards regression was applied to assess prospective associations between job strain across MIDUS I and MIDUS II and CVD mortality at follow-up in 1,870 workers free from CVD at MIDUS I. After adjustment for relevant covariates, single measurement of job strain at MIDUS I or MIDUS II, and two measurements of job strain between the two waves were not significantly associated with CVD mortality, while the increase in scores between the two waves (increase vs. no increase) demonstrated stronger prospective associations with CVD mortality (HR and 95% CI = 2.37 [0.88, 6.42]). Our findings suggest increased job strain may pose a stronger risk to CVD mortality than single exposure measurement.