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

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. A nationwide sample of 22,582 Korean workers (10,266 men, 12,316 women) was analyzed. Weekly working hours were measured at baseline. The outcomes were the all-cause and CVD deaths. Cox regression models were 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). During a median follow-up of 9.6 years, 670 all-cause deaths and 129 CVD deaths occurred. In the male workers, the HRs (95% CIs) for the association of working ≥55 h/week with mortality outcomes were 1.52 (1.06–2.17) for all-cause mortality and 2.59 (1.02–6.56) for CVD mortality, compared with working 35–40 h/week. In the female workers, the HRs (95% CIs) for the association of working ≥55 h/week with mortality outcomes were 0.74 (0.41–1.33) for all-cause mortality and 1.11 (0.31–6.92) for CVD mortality, compared with working 35–40 h/week. In conclusion, this study suggests that long working hours are linked to all-cause and CVD mortality among male workers.