Letter by Tsuda Regarding Article, "Association Between Visceral and Subcutaneous Adipose Depots and Incident Cardiovascular Disease Risk Factors".

BACKGROUND Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) vary in volume and quality. We evaluated whether fat volume or attenuation (indirect measure of quality) predicts metabolic risk factor changes. METHODS AND RESULTS Framingham Heart Study Multi-detector Computed Tomography Substudy participants (n=1730, 45% women) were followed up over a mean of 6.2 years. Baseline VAT and SAT volume (in cm(3)) and attenuation (in Hounsfield units) were assessed. Outcomes included blood pressure, lipids, and glucose. We constructed multivariable regression models predicting change from baseline to follow-up. Baseline VAT was associated with metabolic risk factors at follow-up. Per 500-cm(3) increase in baseline VAT, glucose was 2.34 mg/dL higher (95% confidence interval, 1.71-2.97) and high-density lipoprotein was 1.62 mg/dL lower (95% confidence interval, 0.97-2.28) in women (P<0.0001 for both). These findings remained significant after adjustment for body mass index. Results for SAT were similar although less striking. Lower (more negative) fat attenuation was associated with more adverse metabolic profiles at follow-up. For example, per 5-unit decrease in baseline VAT Hounsfield units, log triglycerides increased by 0.08 mg/dL (95% confidence interval, 0.05-0.12; P=0.005), which remained significant after adjustment for baseline VAT. Among men, VAT and SAT Hounsfield units were associated with changes in cardiovascular disease risk factors but were mostly attenuated after baseline volume adjustment. CONCLUSIONS VAT volume and SAT volume are associated with incident metabolic risk factors beyond overall adiposity. Decreases in fat attenuation are also associated with incident risk factors. These findings suggest that both volume and quality of VAT and SAT contribute to metabolic risk.