Weight Changes When Switching PWH from ABC or TDF to TAF

A study looked at weight gain when changing therapy regimens.


One of the associated side effects of people with HIV has been weight gain and specifically when associated with the use of integrase inhibitors (INSTIs) and possibly with nucleoside reverse transcriptase inhibitors (NRTIs).

In an international study, investigators wanted to understand the effects of switching regimens from either a Tenofovir Disoproxil Fumarate (TDF) or Abacavir (ABC) to Tenofovir Alafenamide (TAF), and if it would prompt weight changes.

In fact, investigators did find a difference in the various regimens. “Switching from TDF to TAF in INSTI-based regimens had a greater risk of weight gain vs ABC to TAF,” they wrote. “This difference persisted when accounting for impact of the INSTI agent in the current regimen. These data suggest that differences in weight gain between TAF and TDF are driven by removal of TDF-associated weight suppression.”

Participants in the study had HIV, had to be at least 18 years old, was treatment-experienced with known prior regimen, suppressed at index and 1 year, more than 6 months pre-index history, with weight measures at index and 1 year, no current or pre-index use of protease inhibitor or non-nucleoside reverse transcriptase inhibitor.

“Univariate comparisons were performed using Χ2 for categorical and t-test for continuous variables; negative binomial model with log link function evaluated risk of gain ≥ 3% of body weight between groups accounting for age, gender, race, body mass index (BMI), CD4. Linear mixed effects model was used to estimate mean weight at index and 1 year post switch.”

In the study, 828 of the 970 participants switched from TDF to TAF and 142 from ABC to TAF. The two cohorts were balanced by race, gender, and index BMI. At the 1 year mark, mean unadjusted weight change was 1.4 kg in the TDF group and 0.2 in ABC group.

“TDF to TAF had higher proportion of PWH with gain ≥ 3% vs ABC to TAF (40% vs 27%); differences in gain ≥ 5% and ≥ 10% were not statistically significant (26% vs 22% and 10% vs 6%). Pts who gained ≥ 3% were younger, with greater proportion of females, non-obese, with 1 prior regimen, and prior elvitegravir (EVG) use. In adjusted analysis TDF to TAF had higher risk of gain more than 3% vs ABC to TAF.”

The study, Weight Change in Suppressed People with HIV (PWH) Switched from Either Tenofovir Disoproxil Fumarate (TDF) or Abacavir (ABC) to Tenofovir Alafenamide (TAF) was presented virtually as a late breaking abstract at IDWeek 2020.