Relationship between shift work and onset of hypertension in a cohort of manual workers

Objectives This study investigated the possibility of a relationship betwee n blood pressure level and rotating 3-shift work in a prospective follow-up of workers in a zipper and aluminum sash factory in Japan. Methods Altogether 1551 men aged 18-49 years were followed prospectively fo r 5 years, and the cumulative incidence of hypertension among 3-shift worke rs was compared with that of day workers. A multiple logistic analysis was used for adjusting for base-line characteristics such as age, body mass ind ex, blood pressure, and drinking habit. Results In the younger age group, the relative risk of the rotating 3-shift workers during the observational period was increased compared with that o f day workers after adjustment for the confounding factors. In the older gr oup, the cumulative incidence of hypertension was not higher for workers wh o had continued shift work. However, a relatively high risk of hypertension was found for workers who converted from S-shift work to day work when com pared with those who remained on shift work and day work. Conclusions It is suggested that there is an association between S-shift wo rk and blood pressure.