Fat mass ratio: an objective tool to define lipodystrophy in hiv-infected patients under antiretroviral therapy

Human immunodeficiency virus (HIV) infection and its treatment with antiretroviral therapy (ART) have been associated with lipodystrophy. Different clinical methodologies have been used to define the syndrome. The aim of this study was to propose gender-specific reference values using objective measurements for defining lipodystrophy in HIV-infected patients. Using dual-energy X-ray absorptiometry (DXA), total body composition was analyzed in 221 HIV-infected patients under ART (146 men). We used fat mass ratio (FMR) as the ratio between the percent of the trunk fat mass and the percent of the lower-limb fat mass. One hundred forty patients (63.6%) presented clinically defined lipodystrophy. In men, the optimal cutoff value for the FMR was 1.961 (area under the receiver operating characteristic curve [AUC]: 0.74 [95% confidence interval (CI): 0.66-0.82], p<0.001), with a sensitivity 58.3%, a specificity 83.7%, a positive predictive value (PPV) of 89.6% and a negative predictive value (NPV) of 45.5%. In women, the optimal cutoff value for the FMR was 1.329 (AUC: 0.74 [95% CI: 0.63-0.86], p<0.001), with a sensitivity 51.4%, a specificity 94.6%, a PPV of 90.5%, and an NPV of 66.0%. The FMR evaluated by DXA with the gender-specific cutoffs defined here is an objective way to define HIV-related lipodystrophy.