Duration of exposure to night work and cardiovascular risk factors: results from 52,234 workers of the CONSTANCES study.

BACKGROUND

The cardiovascular consequences of night work are increasingly well-known. Implementing effective preventive strategies, however, requires further investigation of the effects of exposure duration. This study sought to assess the cumulative dose-effect of night work exposure on the prevalence of cardiovascular risk factors among current and former night workers in France.

METHODS

We used cross-sectional data from the CONSTANCES cohort to design analyses on 52,234 workers exposed or not exposed to night work during their working life. The cumulative duration of night work exposure was assessed among permanent, rotating and former night workers. BMI, blood pressure, lipids, glycaemia and SCORE2 were measured in health screening centres.

RESULTS

Excess risks of moderate-high SCORE2 were observed for permanent (+ 43%), rotating (+ 72%) and former night workers (+ 101%). Among male permanent night workers, excess risks for obesity (+ 76%) and central obesity (64%) were recorded at five years of exposure and for T2DM (+ 119%) at 10 years of exposure. Male rotating night workers showed excess risks at five years of exposure for obesity/central obesity (about + 45%) and high triglyceridaemia (+ 52%). Female former night workers were at excess risk at five years of exposure for obesity/central obesity (about + 45%), HBP (+ 34%) and low-HDL-C (+ 35%).

CONCLUSIONS

The effects on cardiovascular risk factors varied according to the types of night work and within sex groups. Some effects were observed after five years of exposure. These results support the need for early and appropriate monitoring of cardiovascular risk factors among current and former night workers.