The relation between body mass index and target organ damage and the mediating role of blood pressure.

Background/objectives: The relationship between obesity and blood pressure (BP) is well known, but limited data exists regarding its relationship with target organ damage (TOD). Therefore, this study aimed to examine the relationship between body mass index (BMI) and TOD and the mediating role of BP.

Subjects/methods: 2555 adults (52.0% women) who visited a local Hypertension Unit with valid measures on weight, height, 24 h ambulatory BP monitoring, office BP measurements, echocardiography, carotid ultrasonography and blood creatinine levels, included in this cross-sectional study. BMI was used to categorize participants as having normal weight (< 25 kg/m²), overweight (25-29.9 kg/m²) or obesity (≥ 30 kg/m²). The intima-media thickness (IMT) of the common (CCA) and the internal (ICA) carotid artery, left ventricular mass (LVM), LVM index (LVMI) and estimated glomerular filtration rate (eGFR) were estimated and used as TOD indices. Linear regression models were used to examine the relationship between obesity and BP measurements or TOD, while structural equation modeling (SEM) for mediation analysis.

Results: Obesity was significantly related to 24-hour systolic BP (b = 3.72, 95%CI: 2.24-5.21, p < 0.001), CCA-IMT (b = 0.04, 95%CI: 0.02-0.05, p < 0.001), ICA-IMT (b = 0.03, 95%CI: 0.01-0.05, p = 0.020), and LVMI (b = 7.54, 95CI%: 4.25-10.83, p < 0.001). The mediation analysis revealed that 24-hour systolic BP mediated by 27.9% the relationship between BMI and CCA-IMT, by 31.3% the relationship between BMI and ICA-IMT, and by 18.1% the relationship between BMI and LVMI.

Conclusions: These results indicate that obesity is associated with indices of asymptomatic cardiac remodeling and vascular atherosclerosis, and systolic BP mediates these relationships.