Does working long hours increase the risk of cardiovascular disease for everyone?

• Published in: Journal of occupational health Vol. 61; no. 6; pp. 431 - 441
• Main Authors: Lee, Dong‐wook, Kim, Hyoung‐Ryoul, Myong, Jun‐Pyo, Choi, Jaesung, Hong, Yun‐Chul, Kang, Mo‐Yeol
• Format: Journal Article
• Language: English
• Published: Australia John Wiley & Sons, Inc 01.11.2019; John Wiley and Sons Inc
• Subjects: Adult; Aged; Cardiovascular disease; Cardiovascular diseases; Cardiovascular Diseases - epidemiology; Economic models; Family income; Female; health inequality; Health risks; Heart diseases; Households; Humans; Income; Korea - epidemiology; Korean national health and nutrition examination survey; long working hours; Low income groups; Male; Males; Middle Aged; Nutrition; Nutrition Surveys; Occupational Diseases - epidemiology; Occupational health; Original; Originals; Quartiles; Risk; Risk Factors; Shift work; Socioeconomic Factors; socioeconomic status; Socioeconomics; Time Factors; Working conditions; Working hours; Workload; Korea; cardiovascular disease; health inequality; Korean national health and nutrition examination survey; long working hours; socioeconomic status
• ISSN: 1348-9585; 1341-9145; 1348-9585
• DOI: 10.1002/1348-9585.12069

Introduction It has been suggested that long working hours are associated with cardiovascular disease (CVD). Although studies on health inequality caused by income inequality have been performed, income levels of workers have been considered only as an adjusting factor in the relationship between long working hours and CVD. In the present study, we investigated the modifying effects of household income level in the relationship between working hours and estimated risk of CVD. Materials and Methods We analysed a total of 11,602 Koreans who were randomly enrolled in the Korea National Health and Nutrition Examination Survey (2007‐2016) with complete data. Nonparametric associations between weekly working hours and estimated risk of CVD were explored according to quartiles of equalised household income by gender, and the size of linear associations among weekly working hours and estimated CVD risk after stratifying for equalised household income by gender was considered. Results A 4.1% increased risk of CVD was associated with 10 hours or longer per day weekly working hours among males with the highest household income after adjusting for age, equalised household income, occupation, and shift work, but such was not associated among lower income groups. Negative associations between equalised household income and estimated CVD risk were observed only among low household income males. Conclusion Long working hours and household income level can have differential effects on the risk of CVD by socioeconomic status. This study shows that positive income effect may dominate the potential negative effect of long working hours with respect to the risk of CVD in the low‐income group.