Original Article
Copyright ©2009 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Dec 7, 2009; 15(45): 5654-5661
Published online Dec 7, 2009. doi: 10.3748/wjg.15.5654
Shift work aggravates metabolic syndrome development among early-middle-aged males with elevated ALT
Yu-Cheng Lin, Tun-Jen Hsiao, Pau-Chung Chen
Yu-Cheng Lin, Department of Occupational Medicine, Tao-Yuan General Hospital, Tao-Yuan 330, Taiwan, China
Yu-Cheng Lin, Pau-Chung Chen, Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, No. 17, Xu-Zhou Road, Taipei 100, Taiwan, China
Tun-Jen Hsiao, College of Public Health and Nutrition, Taipei Medical University, Taipei 110, Taiwan, China
Author contributions: Lin YC and Chen PC contributed equally to this work; Lin YC designed and performed the research; Hsiao TJ contributed to the data collection; Lin YC and Chen PC analyzed the data; Lin YC wrote the paper.
Correspondence to: Pau-Chung Chen, MD, PhD, Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, No. 17, Xu-Zhou Road, Taipei 100, Taiwan, China. pchen@ntu.edu.tw
Telephone: +886-2-33228088 Fax: +886-2-23582402
Received: June 23, 2009
Revised: September 14, 2009
Accepted: September 21, 2009
Published online: December 7, 2009
Abstract

AIM: To examine whether shift work accelerates metabolic syndrome (MetS) development among early middle-aged males with elevated alanine aminotransferase (e-ALT).

METHODS: A retrospective, observational follow-up study on MetS development at a 5-year interval was conducted using health examination data. Nine hundred and ninety six male employees not fulfilling MetS criteria at screening were enrolled. Age, MetS-components, liver enzymes, serological markers for viral hepatitis, abdominal ultrasound, insulin resistance status, lifestyles, and workplace factors were analyzed.

RESULTS: The prevalence of elevated serum ALT (> 40 U/L, e-ALT) at baseline was 19.1%. There were 381 (38.3%) workers with long-term exposures to day-night rotating shift work (RSW). 14.2% of subjects developed MetS during follow-up. After 5 years, the workers with e-ALT had significantly unfavorable changes in MetS-components, and higher rates of MetS development, vs subjects with normal baseline ALT levels. Workers with both baseline e-ALT and 5-year persistent RSW (pRSW) exposure had the highest rate of MetS development. Also, e-ALT-plus-pRSW workers had a significant increase in MetS-components at follow-up, compared with the other subgroups. After controlling for potential confounders, e-ALT-plus-pRSW workers posed a significant risk for MetS development (odds ratio, 2.7; 95% confidence interval, 1.4-5.3, vs workers without baseline e-ALT nor pRSW).

CONCLUSION: We suggest that all early middle-aged male employees with e-ALT should be evaluated and managed for MetS. Particularly in terms of job arrangements, impacts of long-term RSW on MetS development should be assessed for all male employees having baseline e-ALT.

Keywords: Alanine aminotransferase; Early middle aged; Male; Metabolic syndrome; Shift work