Long working hours causes several health risks, but little is known about its effects on the liver. This study aimed to examine the correlation between working hours and abnormal liver enzyme levels.
We used data from the Korea National Health and Nutrition Examination Survey IV–VII. For the final 15,316 study participant, the information on working hours was obtained through questionnaires, and liver enzyme levels, consisting of serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), through blood tests. The relationship between weekly working hours and abnormal levels of liver enzymes was analyzed using multiple logistic regression, and a trend test was also conducted.
In male, working ≥ 61 hours per week was significantly associated with elevated AST and ALT levels compared with working 35–52 hours per week. Even after adjusting for covariates, the odds ratios (ORs) of abnormal AST and ALT increased by 1.51 (95% confidence interval: 1.20–2.05) and 1.25 (1.03–1.52), respectively, and a dose-response relationship was observed. This association was more prominent among the high-risk group, such as those aged > 40 years, obese individuals, worker on non-standard work schedule, pink-collar workers, or temporary worker. No correlation was observed in female.
Long working hours are associated with abnormal liver function test results in male. Strict adherence to statutory working hours is necessary to protect workers’ liver health.
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Shift work has well-known adverse effects on health. However, few studies have investigated the relationship between shift work and hepatic disorders. This study aimed to evaluate the association between shift work and abnormal level of liver enzymes.
The aggregated data from the 2007–2009, 2010–2012, and 2013–2015 cycles of the Korea National Health and Nutrition Examination Survey was used for this study. The χ2 test and multiple logistic regression analysis were used to assess relationship between shift work and abnormal level of liver enzymes stratified by gender.
The odds ratio (OR) of abnormal serum level of alanine aminotransferase (abnormal ALT) in female shift workers was higher with 1.31 (95% confidence interval: 1.00–1.71) compared with day workers after adjusting for covariates. After dividing into subgroups of the shift work pattern, the ORs of abnormal liver enzymes for each pattern compared with day work were not significantly higher.
This study provides limited support for the hypothesis that shift work is related to liver enzyme abnormalities, but offers some evidence in favor of the idea that shift work affects female workers more than males on abnormal ALT. Further studies are needed to define the relationship between shift work and abnormal liver enzymes to be carried out as well as the gender difference in the association.
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