8277053 Associations between shift work and cardiovascular diseases in the prospective heinz nixdorf recall study

<h3>Objective</h3> Shift work is discussed as risk factor for cardiovascular diseases as it can disrupt the circadian system, which is involved in the regulation of cardiovascular functions. Here, we analyze associations between shift work and incident cardiovascular diseases (myocardial infarction, coronary heart disease, sudden cardiac death, stroke, transient ischemic attack). <h3>Material and Methods</h3> Incident cardiovascular diseases were defined as fatal or non-fatal cardiac or cerebrovascular events, or interventional coronary revascularizations in the German prospective population-based Heinz Nixdorf Recall study. Lifetime shift work information was assessed retrospectively. We calculated incidence rate ratios (IRR) and 95% confidence intervals (CI) with log-linear Poisson regression models with the logarithm of person-years as offset for the effect of shift and night-shift work on incident cardiac and cerebrovascular events jointly and separately. Based on a directed acyclic graph, the models were adjusted for age, sex, educational years, and preferred midpoint of sleep as proxy for the chronotype. Stratified analyses by sex and chronotype were also performed. <h3>Results</h3> We found no increased risk for cardiac and cerebrovascular events (N=3023; shift work for at least 1 year: IRR=0.87, 95% CI=0.68-1.10; night-shift work for at least 1 year: IRR=0.87, 95% CI=0.66-1.14). For women with night-shift work, we observed increased risk estimates (N=1438 with 91 night-shift workers; model for night-shift work for at least 1 year: IRR=1.56, 95% CI=0.76-3.22; model for duration of night-shift work: 1-&lt;10 years: IRR=1.11, 95% CI=0.35-3.50; 10+ years: IRR=2.05, 95%CI=0.75-5.61). Stratification by preferred midpoint of sleep did not show increased risks in relation to chronotypes. The separate analysis of cerebrovascular events showed more pronounced risk estimates, but lower precision. <h3>Conclusion</h3> Overall, we found no unambiguous associations between shift work and cardiovascular diseases. Slightly increased risk estimates for women indicate a vulnerable subgroup, but small case numbers limit the meaningfulness of our results.