Shift Work and the Relationship with Metabolic Syndrome in Chinese Aged Workers

BACKGROUND Shift work is indicated to be associated with adverse metabolic disorders. However, potential effects of shift work on metabolic syndrome (MetS) and its components have not been well established. METHODS In total, 26,382 workers from Dongfeng-Tongji Cohort were included in this study. Information on shift work history was gathered through questionnaires and metabolic traits were measured. Logistic regression models were used to calculate the odds ratio (OR) and 95% confidence interval (CI) for long-term shift work related with MetS and each component, respectively. Further stratification analysis was performed to detect the differences on MetS between female and male shift workers. RESULTS Long-term shift work was associated with MetS without adjusting for any confounders. Compared with the group of non-shift work, the multivariate-adjusted ORs (95%CI) of MetS associated with 1-10, 11-20, and ≥20y of shift work were 1.05 (0.95-1.16), 1.14 (1.03-1.26), 1.16 (1.01-1.31), respectively. In female workers, we found a dose-response relationship that every 10 years increase in shift work was associated with a 10% (95% CI: 1%-20%) elevated OR of MetS, while no significant dose-response trend was found among male workers. Furthermore, shift work duration was significantly associated with ORs of high blood pressure (1.07, 1.01-1.13), long waist circumference (1.10, 1.01-1.20) and high glucose levels (1.09, 1.04-1.15). No significant association was observed between shift work and low HDL cholesterol) and raised triglyceride levels. CONCLUSIONS Long-term shift work was associated with metabolic syndrome and the association might differ by gender in retired workers. Applicable intervention strategies are needed for prevention of metabolic disorders for shift workers.