Long Working Hours and the Prevalence of Masked and Sustained Hypertension.

Previous studies on the effect of long working hours on blood pressure have shown inconsistent results. Mixed findings could be attributable to limitations related to blood pressure measurement and the lack of consideration of masked hypertension. The objective was to determine whether individuals who work long hours have a higher prevalence of masked and sustained hypertension. Data were collected at 3-time points over 5 years from 3547 white-collar workers. Long working hours were self-reported, and blood pressure was measured using Spacelabs 90207. Workplace clinic blood pressure was defined as the mean of the first 3readings taken at rest at the workplace. Ambulatory blood pressure was defined as the mean of the next readings recorded every 15 minutes during daytime working hours. Masked hypertension was defined as clinic blood pressure < 140/90 mm Hg and ambulatory blood pressure ≥135/85 mm Hg. Sustained hypertension was defined as clinic blood pressure ≥140/90 mm Hg and ambulatory blood pressure ≥135/85 mm Hg or being treated hypertension. Long working hours were associated with the prevalence of masked hypertension (prevalence ratio 49+=1.70 [95% CI, 1.09-2.64]), after adjustment for sociodemographics, lifestyle-related risk factors, diabetes mellitus, family history of cardiovascular disease, and job strain. The association with sustained hypertension was of a comparable magnitude (prevalence ratio 49+=1.66 [95% CI, 1.15-2.50]). Results suggest that long working hours are an independent risk factor for masked and sustained hypertension. Workplace strategies targeting long working hours could be effective in reducing the clinical and public health burden of hypertension.