Night shift work and abnormal liver function: is non-alcohol fatty liver a necessary mediator?. Issue 2 (4th December 2018)

• Record Type: Journal Article
• Authors: Wang, Feng; Zhang, Liuzhuo; Wu, Suyang; Li, Wentao; Sun, Miaomiao; Feng, Wenting; Ding, Ding; Yeung-shan Wong, Samuel; Zhu, Peng; Evans, Greg J; Wing, Yun Kwok; Zhang, Jihui; Vlaanderen, Jelle J; Vermeulen, Roel C H; Zhang, Yanfang; Chan, Emily Ying-yang; Li, Zhimin; Tse, Lap Ah
• Is Part Of: Occupational and environmental medicine. Volume 76:Issue 2(2019)
• Page Start: 83
• Page End: 89
• Publication Date: 2018-12-04
• Subjects: shift work -- liver function -- mediation effect -- non-alcoholic fatty liver; Medicine, Industrial -- Periodicals; Environmental health -- Periodicals; 616.980305
• DOI: 10.1136/oemed-2018-105273
• Languages: English
• ISSNs: 1351-0711

Abstract

Abstract : Objectives: Accumulated evidence implies that night shift work may trigger liver dysfunction. Non-alcoholic fatty liver (NAFL) is suggested to be a necessary mediator in this process. This study aimed to examine the relationship between night shift work and elevated level of alanine transaminase (e-ALT) of workers and investigate the potential mediation effect of NAFL. Methods: This study included all male workers from the baseline survey of a cohort of night shift workers. Information on demographics, lifestyle and lifetime working schedule was collected by face-to-face interview. Liver sonography was used to identify NAFL cases. Serum ALT level was detected by an automatic biochemical analyser. e-ALT was defined as ALT >40 U/L. Logistic regression models were used to evaluate ORs, and mediation analysis was employed to examine the mediation effect. Results: Among 4740 male workers, 39.5% were night shift workers. Night shift workers had an increased risk of e-ALT (OR, 1.19, 95% CI 1.00 to 1.42). With the increase in night shift years, the OR of e-ALT increased from 1.03 (95% CI 0.77 to 1.36) to 1.60 (95% CI 1.08 to 2.39) among workers without NAFL. A similar trend was not found among workers with NAFL. In addition, no significant mediation effect of NAFL in the association between night shift work and e-ALT was found. Conclusions: Night shift work is positively associated with abnormal liver function, in particular among workers without NAFL. Shift work involving circadian disruption is likely to exert a direct effect on liver dysfunction rather than rely on the mediation effect of NAFL.