[Relationship between change in body mass index and blood pressure in urban residents].

PURPOSE: The aim of this study was to assess the relationship between change in body mass index (BMI) and blood pressure in urban residents. METHODS: The data for this study were obtained at health checkups carried out between 1984 and 1998 in city A in Osaka Prefecture. The subjects comprised 4,760 men and 9,318 women aged 40-69. Individuals who had taken anti-hypertensives as medical treatment were not included. Hypertension was defined as a systolic blood pressure (SBP) > or = 140 mmHg or as a diastolic blood pressure (DBP) > or = 90 mmHg. We divided the 15 year period into three of five-years each and divided the subjects with reference to their BMI (Body Mass Index: kg/m2). We calculated the averages of systolic blood pressure and those of diastolic blood pressure in every group and the regression equations of BMI to blood pressure by means of single regression analyses. Hypertension incidences were determined in every ten years. Among the subjects who had taken health checkups between 1984 and 1988, we analyzed the relationship between change in BMI and blood pressure. RESULTS: 1. In all three-period groups, the averages for SBP and DBP in the highest BMI group were significantly larger than in the lowest group. 2. Linear regression coefficients for the relation of BMI to blood pressure were significantly positive in all age groups for both men and women. 3. The incidence of hypertension displayed a tendency to depend on BMI values positively. Especially, rising BMI values in women were significantly associated with increase of the incidence of hypertension. 4. In each of the years (1984-1988), in the group with decreasing BMI the average values for blood pressure were smaller than those in the increasing group. In some years, the statistical significance was attained. CONCLUSION: According to the present analyses of health checkup data for urban residents, both blood pressure and the incidence of hypertension positively depend on BMI. This study of transitions showed decrease of BMI to exert a beneficial influence on blood pressure.