Risk factors for the development of hypertension: a 6-year longitudinal study of middle-aged Japanese men.

To identify the factors related to the development of hypertension on the basis of annual health examinations at the workplace. A cohort of Japanese male office workers who were reexamined for six successive years after their initial examinations in 1990. The study cohort comprised 1089 hypertension-free subjects aged 30-54 years. Six-year follow-ups were completed for 934 subjects (85.8%) An analysis using the Kaplan-Meier method showed that the incidence of hypertension above the borderline level increased significantly with increasing age, body mass index, systolic blood pressure, diastolic blood pressure, total cholesterol level, uric acid level, total protein level, hematocrit level, and alcohol intake. This increase was significant for systolic blood pressure, diastolic blood pressure, and hematocrit level. The highest cumulative incidences both of hypertension above the borderline level and of definite hypertension were observed among those with 85-89 mmHg diastolic blood pressure, and the second highest among those with 130-139 mmHg systolic blood pressure. Multivariate analysis using the Cox proportional hazards model indicated that age, systolic blood pressure, diastolic blood pressure, and alcohol intake were independent factors associated with the incidence of hypertension above the borderline level. Systolic blood pressure, diastolic blood pressure, and hematocrit level proved to be independently predictive of hypertension, and alcohol intake was of borderline significance as a risk factor for hypertension. High normal blood pressure is the strongest predictor for the development of hypertension among middle-aged Japanese men. In addition, high alcohol intake and high hematocrit level may be contributory factors.