Relationship between body mass and ambulatory blood pressure: comparison with office blood pressure measurement and effect of treatment.

Epidemiologic studies assessing the relationship between blood pressure (BP), body mass, and cardiovascular events have primarily been based on office BP measurements, and few data are available in the elderly. The aim of the present study was to evaluate the relationship between body mass index (BMI) and BP values obtained by ambulatory blood pressure monitoring (ABPM) as compared to office BP measurements, and the effect of anti-hypertensive treatment on the relationship. The study population consisted of 813 subjects participating in the cardiovascular abnormalities and brain lesions (CABL) study who underwent 24-h ABPM. Office BP (mean of two measurements) was found to be associated with increasing BMI, for both SBP (p ≤ 0.05) and DBP (p ≤ 0.001). In contrast, there was no association seen of increasing BMI with ABPM parameters in the overall cohort, even after adjusting for age and gender. However, among subjects not on anti-hypertensive treatment, office SBP and DBP measurements were significantly correlated with increasing BMI (p ≤ 0.01) as were daytime SBP and 24-h SBP, although with a smaller spread across BMI subgroups compared with office readings. In treated hypertensives, there was only a trend toward increasing office DBP and increasing DBP variability with higher BMI. Our results suggest that body mass may have a less significant influence on BP values in the elderly when ABPM rather than office measurements are considered, particularly in patients receiving anti-hypertensive treatment.