Shift working and risk of lipid disorders: a cross-sectional study.

Background: previous studies have indicated on association between shift work and lipid profile disturbances. Lipid profile disturbances could be due to internal desynchronization. The aim of this study was to analyze whether there is relationship between shift work and serum lipids, fasting blood glucose and hypertension.
Results: A total of 424 rail road workers between the ages of 21 and 64 years in this study filled out a questionnaire, and total cholesterol, triglyceride and HDL-C concentration were measured after 12-hours fasting. Association between shift work and biochemical variables and blood pressure were measured. The X2 and fisher's exact test was used for comparing the qualitative variables and for quantitative variables with normal distribution we used the parametric tests. Odds ratio (OR) with the 95% confidence interval (95% CI) was used for comparing the proportions of risk variables.Sub-populations in this study were consisting of 158 (37.3%) shift workers and 266 (62.7%) day workers. High levels of total cholesterol (> 200 mg/dl) and LDL-cholesterol (> 130 mg/dl) were significantly more prevalent in nearly all groups of shift workers irrespective of age. But there is no differences in the serum levels of triglyceride, HDL-C, fasting blood glucose and blood pressure between shift workers and day workers.Adjusted Odd's ratio for the effect of shift working on high serum total cholesterol and LDL-C level were 2.11(95%CI: 1.33-3.36) and 1.76(95%CI: 1.09-2.83), respectively.
Conclusion: This study showed that high serum total cholesterol and LDL-C level were more common in shift workers than in day workers. This finding persisted after adjustment was made for age and food type. But there was no difference in the prevalence of HDL-C, triglyceride, fasting blood glucose and hypertension between shift working and day working. It was concluded that shift work is a risk factor for lipid profile disturbances.