OBJECTIVE: The goal of this study was to examine the relationship between shift work and cardiovascular risk factors in a cross sectional survey.
MATERIAL AND METHODS: 2 610 men of the PRIME study, aged 50-60 years, residing in Haute-Garonne (France) and selected from health centers and various firms were screened. White-collar workers, retired and disabled men at the time of the study were excluded so the analysis was performed on a sample of 1,341 subjects. Work was categorized as day work (n = 1,161) and three types of shift work: 2 x 8 (n = 108), 3 x 8 (n = 41) and night (n = 31). A comparison of cardiovascular risk factors was performed in the different types of work.
RESULTS: Univariate analysis showed that systolic blood pressure was significantly higher among 2 x 8 workers (132.7 +/- 17.4 mmHg) than in other shift workers and day workers (126.9 +/- 15.1 mmHg). The same difference was observed for diastolic blood pressure. Plasma triglycerides were significantly higher among night workers (1.60 +/- 0.76 g/l) than among day workers (1.29 +/- 0.81 g/L). Logistic regression analysis showed that the risk of hypertension, defined as systolic (> or = 140 mmHg) and diastolic (> or = 90 mmHg) blood pressure and/or antihypertensive drug, was 2 times higher among 2 x 8 shift workers (OR: 2.14, 95% CI [1.42-3.23]) than among day workers after adjustment for BMI, alcohol and tobacco consumption and plasma triglyceride levels. The same result (OR: 1.99, 95% CI [1.28-3.12] was obtained with a different definition of hypertension (systolic > or = 160 mmHg and/or diastolic > or = 95 mmHg blood pressure and/or antihypertensive drug). Among night workers the risk of triglycerides > 2 g/L was higher (OR: 2.52, 95% CI [1.06-6.01] than among day workers. The risk of both hypertension (140/90 mmHg) and hypertriglyceridemia in comparison to day workers was (OR: 2.01, 95% CI [1.33-3.03]) and (OR: 2.44, 95% CI [1.14-5.21]) for 2 x 8 shift workers and night shift workers respectively.
CONCLUSION: The results of this study, putting into evidence a relationship between shift work, hypertension and high level of triglycerides, justify a careful screening by occupational physicians of cardiovascular risk factors among shift workers.
