Working overtime and risk factors for coronary heart disease: A propensity score analysis based in the J-SHINE (Japanese Study of Stratification, Health, Income, and Neighborhood) study

Background: Evidence on the causal relationship between working overtime and the risk of coronary heart disease is limited. Methods: We surveyed 2355 workers in Japan and conducted propensity-matched logistic regression analysis, using propensity-matched 438 pairs, to evaluate the associations between working overtime (more than 50hr per week) and coronary risk factors: physical inactivity, cigarette smoking, sleep deprivation (<5hr/day), psychological stress, overweight/obesity, and excessive alcohol consumption. The exposure and outcomes were self-reported. Results: Among 2355 workers, 476 participants worked overtime. Propensity-matched analysis revealed that the associations between working overtime and sleep deprivation (odds ratios (OR) and 95% confidence intervals: 2.33, 1.39-3.88) and high stress (2.13, 1.60-2.82). The associations between working overtime and physical inactivity, current smoking, and overweight/obesity were not statistically significant. Excessive alcohol consumption was inversely associated with working overtime. Conclusions: Working overtime was positively associated with two coronary risk factors: sleep deprivation and increased psychological stress.