Effect of Long Working Hours on Cardiovascular Disease in South Korean Workers: A Longitudinal Study

This study aimed to examine the association between working hours and onset of cardiovascular diseases (CVDs) using a prospective study design. We used the Korean Longitudinal Study of Aging (KLoSA) data from 2006 to 2016. A total of 2405 workers who were working 35 hours or more per week and who did not have CVD at baseline were analyzed. Cox proportional hazard model was used for the analysis to determine the association between working hours per week at baseline and the new onset of CVD. In addition, multivariable logistic regression analysis was used to test the relationship between average working hours throughout the entire follow-up period and the risk of CVD (N = 1134). Working above 52 hours per week at baseline was related to higher risk of CVD than working between 35 and 40 hours a week (hazard ratio [HR] = 2.08, 95% confidence interval [CI] = 1.60-2.70 for 52-60 hours; HR = 1.38, 95% CI = 1.05-1.81 for >60 hours). A worker's average working hours throughout the following period were also significantly associated with elevated risks of CVD (odds ratio = 4.40, 95% CI = 1.58-12.22 for >60 hours). The findings underline the need for more proactive interventions to protect the health of workers exposed to long working hours.