8288334 Duration of exposure to night work and cardiovascular risk factors. results from constances, a French population-based cohort

<h3>Objective</h3> To assess the cumulative dose-effect of night work exposure on the prevalence of cardiovascular risk factors (CVRF) among current and former night workers in France. <h3>Material and Methods</h3> Based on the Constances cohort, 52,234 workers were classified as exposed (permanent, rotating and former night work) or non-exposed (daytime) to night work throughout their working life. The duration of exposure to night work was assessed over the entire working career using a self-reported questionnaire. BMI, blood pressure, lipids, and glycaemia were measured in health screening centres. Generalized additive models were used to estimate the probability of being obese, having high blood pressure, lipid disorders, and type 2 diabetes (T2DM) as a function of the duration of exposure for each category of night workers. OR and 95% confidence intervals were estimated, and the reference group consisted of the daytime workers. <h3>Results</h3> The sample comprised 24,892 men and 27,342 women, with an average working career of 20 years. Identified among them were 685 permanent night workers, 915 rotating night workers and 2,972 former night workers. Among male permanent night workers, excess risks for obesity (+76%) and central obesity (64%) were noticed at 5-year exposure and for T2DM (+119%) at 10 years of exposure. Male rotating night workers showed excess risks at 5 years of exposure for obesity/central obesity (about +45%), and high triglyceridaemia (+52%). Female former night workers were at excess risk at 5 years of exposure for obesity/central obesity (about +45%), high blood pressure (+34%) and low-HDL-C (+35%). <h3>Conclusion</h3> The effects on cardiovascular risk factors varied according to the night work profiles and within gender groups. Some effects were observed after only 5 years of exposure. These results support the need for early and appropriate monitoring of cardiovascular risk factors among current and former night workers.