Association between shift work and risk of metabolic syndrome: A systematic review and meta-analysis

Aims A comprehensive assessment of the association of shift work with risk of metabolic syndrome (MetS) through a systematic review and meta-analysis has not been reported. We aimed to evaluate the relationship from observational studies. Data synthesis We searched PubMed, Embase, and Web of Science databases from inception to December 16, 2020. Articles were chosen according to established inclusion criteria. Studies with data on men and women and different types of shift work were treated as independent studies. Relative risks (RRs) and 95% confidence intervals (CIs) were pooled by using random-effects models with heterogeneity (I2) > 50%; otherwise, a fixed-effects model was used. A total of 7192 articles was searched from PubMed, Embase and Web of science. Finally, we included 23 articles (38 studies) in this meta-analysis. The pooled RRs and 95% CI of MetS risk with shift work, 1-shift work, 2-shift work, and 3-shift work versus non-shift work were 1.30 (95% CI 1.19–1.41), 0.95 (95% CI 0.82–1.11), 1.19 (95% CI 0.91–1.56) and 1.17 (95% CI 1.00–1.37), respectively. The results from subgroup analyses stratified by sex, age, and region supported our overall findings that shift work is a risk factor for MetS. Conclusions This meta-analysis suggests that shift work increases risk of MetS. Higher risk of MetS was found in the shift workers who were 2-shift or 3-shift or women or Asian workers.