Results
We examined the demographic characteristics of the patient sample, overall and by BMI category (Table 1) and the association of BMI category with systolic and diastolic blood pressure levels, adjusted for age and diabetes status (Table 2). Overall, the levels increased with BMI (P for trend <.001).
Among patients younger than 65, the association of BMI with blood pressure (both systolic and diastolic) persisted (P for trend <.001). Among patients aged 65 or older, the association of BMI with diastolic BP, but not systolic BP, was significant. The interaction of age and BMI was significant (P < .001).
The association of BMI with both systolic and diastolic BP was positive among non-Hispanic blacks and whites. The interaction of BMI and race was significant (P < .001), demonstrating that the association of BMI and BP was greater for whites.
Among patients younger than 65, the association of BMI with systolic and diastolic BP was positive among non-Hispanic blacks and whites (P for trend <.001 for both groups), and the interaction between BMI and race was significant (P < .001). Among patients 65 years or older, the associations of BMI with diastolic BP were consistently positive for non-Hispanic blacks and whites, whereas the associations of BMI with systolic BP were consistently nonsignificant. The interaction of race and BMI was not significant for this age group.