Body mass index versus height and weight in relation to blood pressure. Findings for the 10,079 persons in the INTERSALT Study.

In INTERSALT, an international study of electrolytes and blood pressure, body mass index (kg/m2) was found to relate independently to blood pressure. These relations were assessed in 10,079 men and women aged 20-59 years from 52 centers around the world, based on a standardized protocol, central training of observers, a central laboratory, and extensive quality control. The purpose of the present analyses was to determine whether weight, directly adjusted for height, related to blood pressure as strongly as did body mass index. For all men and women combined, with adjustment for age, sex, alcohol intake, smoking, and sodium and potassium excretion in addition to height, the partial correlations of blood pressure with weight were 0.221 for systolic blood pressure and 0.238 for diastolic blood pressure. These values were slightly larger than the partial correlations for body mass index with blood pressure, which were 0.215 and 0.229, respectively. Although the regression coefficients for body mass index with systolic pressure had been larger in men than in women, suggesting a stronger association of systolic pressure with weight in men, the models with weight directly adjusted for height indicated that the difference in systolic pressure associated with a 10-kg difference in weight was 3.0 mmHg in both men and women. The corresponding weight-associated diastolic pressure differences ranged from 2.00 mmHg in women aged 40-59 years to 2.7 mmHg in men aged 20-39. In addition, with control for weight, height had a significant inverse association with blood pressure. The results of these analyses support the use of weight, with direct adjustment for height, as a useful and practical substitute for body mass index in analyses of the association of adiposity with blood pressure.