Time of exposure to night work and carotid atherosclerosis: a structural equation modeling approach using baseline data from ELSA-Brasil.

Purpose: The study of cardiovascular diseases (CVD) associated with night work is difficult due to the long period required for conditions to manifest and the healthy-worker effect. Analyzing asymptomatic pre-clinical changes in the atherosclerotic process is a way to assess the pathways between exposure to night work and CVD.

Aim: To evaluate the associations between night work and subclinical atherosclerosis measured by carotid intima-media thickness (CIMT) using baseline data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

Methods: We conducted cross-sectional analyses using baseline data (2008-2010) from 9785 civil servants, aged 35-74 years. The associations between time of exposure to night work and mean CIMT were examined using a structural equation model.

Results: The sample included 4259 men and 5526 women, mean age of 51.6 years. A total of 1778 (18.2%) individuals were exposed to night work (594 current and 1184 former night workers), and the mean years of night work exposed was 11.47 (SD = 9.45) years. On average, mean CIMT was 0.606 (SD = 0.130) mm. Among men, the increase in exposure to night work was significantly associated with an increase in BMI and CIMT. Among women, night work was not associated with increased CIMT. In relation to the indirect associations, results suggest a possible mediation by BMI, diabetes and hypertension on the association between the years of night work and mean CIMT only among men.

Conclusion: Night work was associated with increased CIMT only among men. These findings add to the knowledge of the possible pathways that link night work and carotid atherosclerosis. Additionally, these results contribute to the recognition of work schedules as a public health problem that should be addressed by the medical community and policy makers.