[French shift workers seen at health centres have an increased risk of lipid disorders]

To describe cardiovascular risk factors and metabolic disturbances in a French population including shift workers and study whether possible changes were noticeable after non-shift to shift work transition within the last five years.

The study population included 4764 attendees of two health examinations (5 years apart), between January 1996 and October 2008, in 11 health examination centres. Clinical, biological and metabolic factors together with their changes over a five-year period were compared between attendees who kept a non-shift daytime job, those who kept working shift and those who switched from non-shift daytime to shift work over the last 5 years.

At baseline, working shift was, independently of lifestyle or BMI, significantly related to more elevated plasma triglycerides (β=0.04, P=0.05) and rate of hypertriglyceridemia (β=0.27, P=0.01), lower plasma HDL-C levels (β=-2.03, P=0.006) and less hypertension (β=-0.25, P=0.01) compared to non-shift daytime work. In men, a slightly more elevated yet non significant proportion of hypertriglyceridemia was observed with the transition from non-shift daytime to shift work within the last 5 years in comparison to men who kept a non-shift daytime job (13.9% vs. 11.0% P=0.17).

Our results are in agreement with previous studies showing a deleterious effect of shift work on lipid metabolism. In our population, triglycerides and HDL-C levels were the main parameters negatively influenced by shift work. Consequently, a regular biological monitoring together with the promotion of healthy behaviours should be provided to shift workers before negative consequences of working shift become noticeable.