Impact of body weight on blood pressure with a focus on sex differences - The Tromso study, 1986-1995

Background: The prevalence of obesity and hypertension is increasing in Wes tern societies. We examined the effects of initial body mass index ([BMI] w eight in kilograms divided by height in meters squared) and change in BMI o n change in blood pressure, and we assessed sex differences. Methods: A general population in the municipality of Tromso, northern Norwa y, was examined in 1986 and 1987 and again in 1994 and 1995. Altogether, 75 % of the individuals, women aged 20 to 56 years and men aged 20 to 61 years , attended the baseline examination. A total of 15624 individuals (87% of a ll still living in the municipality) were examined twice. Results:. Mean BMI increased between the examinations, more for the younger than the older examinees, and also more among women than men (P<.001). Adj usted for several covariates, BMI change was associated with systolic and d iastolic blood pressure change for both sexes (regression coefficients: 1.4 3 [95% confidence interval (CI), 1.23-1.64] and 0.90 [95% CI, 0.76-1.04], r espectively, for men; and 1.24 [95% CI, 1.09-1.39] and 0.74 [95% CT, 0.63-0 .84] for women). Baseline BMI was associated with systolic and diastolic bl ood pressure change for women only (regression coefficients: 0.38 [95% CI, 0.30-0.47] and 0.17 [95% CI, 0.11-0.23], respectively). Conclusions: For women, both BMI at baseline and BMI change were independen tly associated with blood pressure change. For a given increase in BMI, obe se women had a greater increase in blood pressure than lean women. This was not the case for men, for whom BMI change was the only significant predict or. Furthermore, a BMI increase for obese women induced a greater systolic blood pressure increase compared with men.