Lifestyle and the development of hypertension: a 3-year follow-up study of middle-aged Japanese male office workers

The association of lifestyle factors with the development of hypertension (blood pressure > or = 140/90 mmHg) over a 3-year follow-up period was studied in 949 hypertension-free Japanese male office workers aged 35 to 54 years. From the Cox proportional hazards model, age, alcohol intake, body mass index (BMI) and hours of work were independent factors associated with the development of hypertension. Adjusted hazard ratios for 5-year increases in age, daily consumption of alcohol, 5-kg/m2 increases in BMI and working 10 hours per day or more were 1.18 [95% confidence interval (CI) = 1.02-1.35]; 1.53 (CI = 1.14-2.05); 1.79 (CI = 1.38-2.33) and 0.58 (CI = 0.41-0.82), respectively. In the analysis using logistic regression, BMI was independently related to working 10 hours per day or more, controlling for other lifestyle factors. Adjusted odds ratio for 5-kg/m2 increase in BMI was 0.66 (CI = 0.49-0.88). These results suggest that the influences of long working hours on blood pressure are likely to be indirectly mediated through less overall obesity.