Risk factors for hypertension. A longitudinal study of middle-aged Japanese male workers

OBJECTIVE: To identify factors related to the development of hypertension among middle-aged Japanese men. METHODS AND RESULTS: A cohort of normotensive male workers aged 30-59 years (n = 6,306) were followed from 1991 through 1998 to observe the development of hypertension, using data from annual health checkups in a Japanese company. With hypertension defined as initiation of antihypertensive therapy or a systolic blood pressure of 140 mmHg or higher and/or a diastolic blood pressure of 90 mmHg or higher, the incidence rate was 33.4/1000 person-years in the 30-39 year old group, 63.8/1000 person-years in the 40-49 year old group, and 75.4/1000 person-years in the 50-59 year old group. Multivariate analysis by using Cox's proportional hazard model indicated that high-normal blood pressure at baseline, obesity (body mass index > or = 25 kg/m2), drinking 5 days/week or more, and no regular exercise were independent factors related to the development of hypertension. Although each age group had a different pattern of risk factors, high-normal blood pressure at baseline was the strongest risk factor in all cases. Glucose intolerance was significantly observed as a hazard only in the 30-39 year old group, hazard rations for obesity and physical inactivity also being highest in this younger age group. CONCLUSIONS: High-normal blood pressure, obesity, glucose intolerance, regular alcohol intake, and physical inactivity are risk factors for hypertension among middle-aged Japanese men. Insulin resistance may play an important role in the development of hypertension in young males.