Association between long working hours and all-cause and cardiovascular disease mortality: A cohort study of Korean workers

Background Long working hours are public health concern globally. However, their association with all-cause and cardiovascular disease (CVD) mortality remains underexplored. This cohort study investigated the relationship between long working hours and all-cause and CVD mortality. Methods A nationwide sample of 22,578 Korean workers (10,266 men, 12,312 women) was analyzed. Weekly working hours were measured at baseline. The outcomes were the all-cause and CVD deaths. Cox regression models was used to determine the relation between working hours and mortality outcomes using a sex-stratified analysis, calculating hazard ratios (HRs) and 95% confidence intervals (CIs). Results The prevalence of long working hours (≥ 55 h/week) was 17.5%. During a median follow-up of 9.6 years, 670 all-cause deaths (2.17 per 1,000 person-years) and 129 CVD deaths (0.41 per 1,000 person-years) occurred. In the overall sample, the HRs (95% CIs) for the association of working ≥ 55 h/week with mortality outcomes were 1.31 (0.97–1.77) for all-cause mortality and 2.20 (1.03–4.73) for CVD mortality, compared with working 35–40 h/week. In male workers, working ≥ 55 h/week was associated with increased risks for both all-cause (HR: 1.55; 95% CI: 1.08–2.22) and CVD mortality (HR: 2.74; 95% CI: 1.08–6.97) compared with working 35–40 h/week. No clear associations emerged among female workers. Conclusion Long working hours are linked to all-cause and CVD mortality among male workers. Policy efforts are need to reduce excess workhours and the associated health burdens.