1067Annual changes in job strain and risk of coronary heart disease in Denmark

Abstract

Abstract Background We examined the association between annual changes in job strain and incident coronary heart disease (CHD) in a population-based cohort study in Denmark. Methods We studied all workers residing in Denmark in 2000, aged 30-59 years with no prevalent CHD (N = 1,660,150). Using a job exposure matrix (JEM) with annual updates, we assessed changes in job strain from 2000-2009. Incident CHD was identified in hospital and death registers from 2001 to 2010. Using Cox regression, we calculated hazard ratios (HR) and 95% confidence intervals (CI) for the association between annual changes in job strain and incident CHD. Results During 16.1 million person-years (mean time of follow-up: 9.7 years), we identified 24,159 CHD cases (15.0 per 10,000 person-years). Compared to persistent no job strain, persistent job strain (HR 1.07, 95% CI 1.03–1.10), onset of job strain (HR 1.20, 95% CI 1.12–1.29) and removal of job strain (HR 1.20, 95% CI 1.12–1.28) were associated with higher CHD incidence. Conclusions Persistent and onset of job strain was associated with a higher risk of CHD. Removal of job strain was also associated with a higher risk, which might be due to health selection. Our results suggest that job strain contributes to risk of CHD in the Danish workforce. Key messages Implementing JEM in a population-based cohort of more than 1.6 million workers enabled us to demonstrate associations between annual changes in job strain and risk of incident CHD.