Weight Change Following Antiretroviral Therapy Switch in People with Viral Suppression: Pooled Data from Randomized Clinical Trials

Background: We sought to identify factors associated with weight gain in randomized clinical trials of antiretroviral therapy (ART) switch. Methods: We explored the effects of demographic factors, clinical characteristics, and ART on weight gain in a pooled analysis of 12 prospective clinical trials, wherein virologically suppressed people living with human immunodeficiency virus (PWH) were randomized to switch or remain on a stable baseline regimen (SBR). Results: Both PWH randomized to switch ART (na=4166) and those remaining on SBR (na=3150) gained weight. Median weight gain was greater in those who switched (1.6 kg, interquartile range [IQR],-.05 to 4.0 vs 0.4 kg, [IQR],-1.8 to 2.4 at 48 weeks, Pa.0001), with most weight gain occurring in the first 24 weeks after switch. Among baseline demographic and clinical characteristics, only younger age and lower baseline body mass index were associated with any or ≥10% weight gain. By week 48, 4.6% gained ≥10% weight (6.4% of switch and 2.2% of SBR), the greatest risk was with switch from efavirenz (EFV) to rilpivirine (RPV) or elvitegravir/cobicistat and switch from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF). Switch from abacavir to TAF was associated with less weight gain than switch from TDF to TAF and was not associated with increased risk for ≥10% weight gain. Conclusions: Moderate weight gain after ART switch was common and usually plateaued by 48 weeks. Baseline ART was a predictor of post-switch weight gain; participants who switched off of EFV and TDF had the greatest weight gain. The biological mechanisms that underlie the differential effects of switching ART agents on weight and associated clinical implications require further study.