with additional reporting by Megan Nicholson
Findings presented at July’s XIV International AIDS Conference challenged prevailing assumptions about the nature of the body fat changes being experienced by people with HIV on antiretroviral treatment, and have provoked widespread debate about how the syndrome should be defined.
Dr Carl Grunfeld of the University of Southern California presented preliminary findings from the Fat Redistribution and Metabolic Change in HIV study (FRAM) at the Barcelona conference. These data are not published in the conference abstract book and were presented in an invited speaker session.
However, the Forum for Collaborative HIV Research this week published a summary of a second presentation of the data, at which lead investigator Carl Grunfeld discussed his findings with a panel of experts (click here to download the summary in pdf form).
The FRAM study was set up to look at body fat changes, and compared 350 HIV-positive men (86% of whom received antiretroviral therapy) and a control group of more than 200 age-matched HIV-negative individuals from the CARDIA cohort, which is evaluating cardiovascular risk factors in younger adults.
The data are cross-sectional – in other words, a snapshot of body fat distribution in study participants at potentially differing points in their treatment history. The investigators didn’t use existing definitions of lipodystrophy, but instead carried out the same measurements in HIV-positive and HIV-negative individuals to find out what differences in body fat distribution existed. They also asked patients and doctors whether they had noticed fat changes, and how severe they were.
The study found that the only distinguishing feature of the syndrome was fat loss – lipoatrophy – and that central fat accumulation was no more common in HIV-positive males than their HIV-negative counterparts. There was no correlation between low levels of peripheral fat and central fat accumulation, suggesting that the syndrome is not one of fat `redistribution`. Instead, men with low levels of peripheral fat also had less central fat. The `buffalo hump` (fat accumulation between the shoulder blades) was no more common in HIV-positive than HIV-negative men.
These findings do not mean that central fat accumulation and peripheral fat loss cannot occur in the same person, said Carl Grunfeld – but the two things are not linked, suggesting that there may be different underlying mechanisms.
The FRAM study at first sight appears to contradict the lipodystrophy definition developed by the HIV Lipodystrophy Case Definition Study, which assigned a score to each of ten variables. However, three of these variables relate to peripheral fat loss or changes in the ratio of subcutaneous fat to visceral fat, and the definition does not include central fat accumulation as a variable except in its relationship to fat loss.
The results of the case definition study are due to be published in the Journal of the American Medical Association shortly.
Further analyses of the FRAM study will look at differences in body fat change according to drug regimen, and differences between men and women.
Further information
aidsmap review of debates over the lipodystrophy definition.
A Medscape review of the FRAM data by Dr. Don Kotler, a FRAM investigator.
A review of case definition debates for the AIDS Reader by Dr Graeme Moyle.