BACKGROUND: Shift work can disrupt circadian rhythms and is postulated to play a role in cardiovascular diseases (CVD). In the German prospective population-based Heinz Nixdorf Recall Study, we analyzed longitudinal associations between shift work and night-shift work with CVD. METHODS: CVD was defined as a fatal or non-fatal cardiac or cerebrovascular event or interventional coronary revascularization during an average follow-up of 15 years. Retrospective shift-work information was assessed as binary and as lifetime duration in years. Adjusted log-linear Poisson regression models were applied to estimate incidence rate ratios (IRR) and 95% confidence intervals (CI) for the effect of shift and night-shift work on incident events. Stratified analyses by sex, diurnal preference, and blue-collar status were also performed. RESULTS: Incident CVD was not associated with shift work (N = 3024; 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). However, we observed sex differences with reduced incidence of CVD for long duration of night-shift work among men (N = 1369 with 380 night-shift workers; model for duration of night-shift work: 1- < 10 years: IRR = 1.08, 95% CI = 0.74-1.57; 10+ years: IRR = 0.64, 95% CI = 0.42-0.96). For women, we found slightly elevated IRRs (N = 1438 with 91 night-shift workers; model for duration of night-shift work: 1- < 10 years: IRR = 1.11, 95% CI = 0.35-3.50; 10+ years: IRR = 2.05, 95% CI = 0.75-5.61). These estimates were stronger in women that never worked in blue-collar jobs (10+ years night-shift work: IRR = 3.22, 95% CI = 1.17-8.92). CONCLUSIONS: We did not observe consistently increased risks of CVD with shift and night workers. However, stratified analyses pointed toward sex- and job-specific vulnerable subgroups.
Wichert et al. (Sun,) studied this question.