An objective case definition of lipodystrophy in HIV-infected adults: a case-control study

Background Lipodystrophy (peripheral lipoatrophy, central fat accumulation, and lipomatosis) is a common and disfiguring problem in adult patients with HIV-1 infection on antiretrovirals. However, an objective, validated definition of the disorder does not exist. We aimed to develop an objective, sensitive, specific, and broadly applicable case definition of HIV lipodystrophy. Methods In a case-control study, 1081 consecutive, HIV-infected, adult outpatients (261 [15%] women) without active AIDS were recruited from 32 sites worldwide. We classed patients with at least one moderate or severe subjective lipodystrophic feature, identified by lipodystrophy-specific physical examination and patient questionnaire, and apparent to both doctor and patient as cases (n=417). We classed patients with no such feature as controls (n=371), and patients without a clear diagnosis as non-assigned. We used objective clinical, metabolic, and body composition measurements to construct a logistic regression model with a subset of randomly selected cases and controls. The model was validated in the remaining patients. Findings A model including age, sex, duration of HIV infection, HIV disease stage, waist to hip ratio, anion gap, serum HDL cholesterol concentration, trunk to peripheral fat ratio, percentage leg fat, and intra-abdominal to extra-abdominal fat ratio had 79% (95% CI 70-85) sensitivity and 80% (95% Cl 71-87) specificity for diagnosis of lipodystrophy. Models that incorporated only clinical, or only clinical and metabolic variables had lower sensitivity and specificity than the inclusive model. Models for lipoatrophy, fat accumulation, and lipomatosis could not be developed since pure phenotypes occurred in fewer than 10% of patients with clinical diagnoses of these disorders. Interpretation Our objective case definition of HIV-associated lipodystrophy should improve assessment of lipodystrophy prevalence, risk factors, and pathogenesis; prevention and treatment approaches; and assist in diagnosis.