Association between long working hours and serum gamma-glutamyltransferase levels in female workers: data from the fifth Korean National Health and Nutrition Examination Survey (2010-2011)

Objectives: The present study investigated the association between long working hours and serum gammaglutamyltransferase (GGT) levels, a factor influencing the incidence of cardiovascular disease. Methods: Data from the fifth Korean National Health and Nutrition Examination Survey (2010-2011) were used to analyze 1,809 women. Subjects were divided into three groups based on the number of weekly working hours: <= 29, 30-51, and >= 52 hours per week. Complex samples logistic regression was performed after adjusting for general and occupational factors to determine the association between long working hours and high serum GGT levels. Results: The prevalence of high serum GGT levels in groups with <= 29, 30-51, and = 52 working hours per week was 22.0%, 16.9%, and 26.6%, respectively. Even after adjusting for general and occupational factors, those working 30-51 hours per week had the lowest prevalence of high serum GGT levels. Compared to those working 30-51 hours per week, the odds ratios (OR) of having high serum GGT levels in the groups with >= 52 and <= 29 working hours per week were 1.56 (95% confidence interval [CI], 1.10-2.23) and 1.53 (95% CI, 1.05-2.24), respectively. Conclusions: Long working hours were significantly associated with high serum GGT levels in Korean women.