The Journal of Clinical Endocrinology & Metabolism, April 2019
Fat quality or function contributes to risk for diseases such as heart disease, fatty liver disease, and diabetes, and may be as important as fat quantity when assessing the risk of poor health outcomes. In the past, fat quality could only be determined by performing fat biopsies and measuring fat cell size under the microscope. However, measuring fat cell density on a CT scan may also measure fat quality (lower density=poorer quality/more poorly functioning fat cells). NWCS 399 compared data from abdominal subcutaneous fat biopsy specimens, with fat density data from CT scans in the ACTG A5224s (a sub-study of A5202, which randomized adults living with HIV to abacavir/lamivudine (ABC/3TC) or tenofovir/emtricitabine (TDF/FTC) with open-label efavirenz (EFV) or atazanavir/ritonavir (ATV/r)).
Over 96 weeks of ART, fat quantity increased (+18%) and fat density decreased (-3%). Mean fat cell area correlated with fat density measured on CT scan both before and after ART and after adjusting for fat quantity, age, race, sex, CD4+ T lymphocyte count, and HIV-1 RNA. Therefore, subcutaneous fat density measured by CT scan served as an accurate representation of subcutaneous fat cell size in adults with HIV on and off ART, suggesting that CT is a useful tool for non-invasive assessment of fat quality.