Persistent rotating shift-work exposure accelerates development of metabolic syndrome among middle-aged female employees: a five-year follow-up.

Limited follow-up studies are available as to whether special job-types, such as day-night rotating shift work, contribute to the progression of metabolic syndrome among female industrial employees. A retrospective cohort study on the development of metabolic syndrome was conducted by utilizing health examination records for a five-year interval. The records of 387 female employees without metabolic syndrome at baseline were used for the analysis. Data analyzed included age, metabolic syndrome components, insulin resistance status, lifestyle factors, and job-types. The initial mean age of subjects was 32.8 yrs. Abnormal rates at baseline, including metabolic syndrome components and insulin resistance, were all significantly higher among the 34 female workers with metabolic syndrome outcome. Also, the persistent rotating shift-work exposure rates and five-year change of metabolic syndrome component measurements were significantly unfavorable for subjects with metabolic syndrome outcome. After controlling for the potential confounders, significant raised risks were found in the female worker with persistent rotating shift-work exposure (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.3-9.0 vs. day workers) and in smokers (OR, 5.4; 95% CI, 1.1-25.8 vs. non-smokers). At the same time, the female workers initially with one or two metabolic syndrome components had a 4.6-fold (95% CI, 1.3-17.0) and 12.7-fold (95% CI, 3.2-50.1), respectively, increased risk of progressing to metabolic syndrome within five years. In conclusion, persistent day-night rotating shift work, smoking, and baseline metabolic syndrome components associate with the progression toward metabolic syndrome for middle-aged female workers.