Surrogate markers of visceral adipose tissue in treated HIV-infected patients: accuracy of waist circumference determination
The accuracy of the use of anthropometrics to quantify visceral adipose tissue (VAT) in treated HIV-infected patients is unknown. We evaluated the predictive accuracy of waist circumference (WC) with and without dual-energy X-ray absorptiometry (DXA)-derived trunk : limb fat ratio [fat mass ratio (FMR)] as surrogates for VAT determined using computerized axial tomography (CT-determined VAT).
We performed a retrospective cohort analysis of treated HIV-infected male patients followed at the Modena HIV Clinic. We developed prediction equations for VAT using linear regression analysis and Spearman correlations. Receiver operating characteristic (ROC) analysis evaluated the accuracy of WC alone or with FMR at discrete VAT thresholds.
The 1500 Caucasian male patients had a median age of 45 years, body mass index (BMI) of 24, WC of 87 cm, VAT area of 127 cm2 and body fat percentage of 14%. The correlation between WC-predicted VAT and CT-VAT was 0.613, and this increased significantly if FMR was added. The WC-associated R2 of 0.35 increased to 0.51 if the prediction equation included WC plus FMR. The area under the ROC curve (AUC) using WC was 0.795−0.820 at all VAT thresholds. The positive predictive value (PPV) and negative predictive value (NPV) changed reciprocally at CT-VAT thresholds from 75 to 200 cm2 and ranged from 0.72 to 0.74, respectively, at a representative VAT of 125 cm2. Adding the FMR to the predictive equations increased the AUC in the range of 0.854−0.889 with the PPV and NPV increasing minimally, ranging from 0.780 to 0.821. Limits of precision were wide, especially at the highest CT-VAT levels, and varied from 24 to 68 cm2.
WC is a limited surrogate for CT-VAT in this population and DXA-derived parameters do not improve performance indices to a clinically relevant level. These findings should inform the applicability of WC to predict VAT in treated HIV-infected male patients.