Rotating shift work, with night shift work, affects cardiovascular risk factors: a 6-year follow-up study in the insulation industry.

Abstract

To assess absolute levels and longitudinal changes in cardiovascular disease (CVD) risk factors over 6 years among rotating shift workers with night shift work and day workers in industry. We studied three groups, 32 night shift workers in Plant A with a high night load, 23 in Plant B with a low night load and 25 day workers during a 6-year follow-up (FU). We collected demographics by questionnaire, measured blood pressure, resting heart rate, carotid intima-media thickness (cIMT), carotid to femoral pulse wave velocity (cfPWV) and maximal oxygen uptake (V̇O_2max). We analysed blood samples including lipids, glycosylated haemoglobin (HbA1c) and C reactive protein (CRP). Mixed models were used to assess changes and differences in changes of these outcomes between shift and day workers. Over the 6-year FU weight, cfPWV and CRP increased among shift workers with a high night load, and cIMT increased among shift workers with a low night load and among day workers. Over the 6-year FU, a significant decrease in V̇O_2max and an increase in HbA1c were found among all workers. The decrease in V̇O_2max and increase in HbA1c were associated with number of years in shift work. Rotating shift work with night shift work in industry associates with weight increase, inflammation, arterial stiffness, increase in cIMT and HbA1c but also decreased V̇O_2max. Reducing the number of night shifts and including periods of restitution in the shift plan seem to mitigate some of the CVD risk factors.