JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
CUHK Centre for Public Health and Primary Care (Shenzhen), Shenzhen Research Institute of the Chinese University of Hong Kong, Hong Kong, China.
Occup Environ Med. 2019 Feb;76(2):83-89. doi: 10.1136/oemed-2018-105273. Epub 2018 Dec 4.
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.
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.
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.
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.
越来越多的证据表明，夜班工作可能会引发肝功能异常。非酒精性脂肪肝（NAFL）被认为是这一过程中的一个必要中介。本研究旨在检验夜班工作与工人丙氨酸氨基转移酶（e-ALT）水平升高之间的关系，并探讨 NAFL 的潜在中介作用。
本研究纳入了夜班工人队列基线调查的所有男性工人。通过面对面访谈收集人口统计学、生活方式和终身工作时间表信息。使用肝脏超声检查来识别 NAFL 病例。血清 ALT 水平通过自动生化分析仪检测。e-ALT 定义为 ALT>40 U/L。使用逻辑回归模型评估 OR，采用中介分析检验中介效应。
在 4740 名男性工人中，39.5%为夜班工人。与非夜班工人相比，夜班工人发生 e-ALT 的风险增加（OR=1.19，95%CI：1.00 至 1.42）。随着夜班年限的增加，在没有 NAFL 的工人中，e-ALT 的 OR 从 1.03（95%CI：0.77 至 1.36）增加到 1.60（95%CI：1.08 至 2.39）。而在有 NAFL 的工人中则未发现类似的趋势。此外，在夜班工作与 e-ALT 之间的关联中，NAFL 并无显著的中介作用。
夜班工作与肝功能异常呈正相关，尤其是在没有 NAFL 的工人中。昼夜节律紊乱的轮班工作可能对肝功能异常直接产生影响，而不是依赖于 NAFL 的中介作用。
