Weight and body mass index increase after switch from tenofovir disoproxil fumarate to tenofovir alafenamide fumarate-containing treatment in an antiretroviral therapy-experienced group.

Tenofovir alafenamide fumarate (TAF) is an alternative to tenofovir disoproxil fumarate (TDF). Currently, TAF is increasingly being used because of its non-inferior antiviral properties, lower risk of nephrotoxicity, and lower decrease in bone mineral density than TDF. There is growing evidence of unfavorable effects of TAF on weight and body mass index (BMI) in antiretroviral therapy (ART)-experienced patients treated with TAF-based ART. The aim of this study was to evaluate whether switching from TDF-containing to TAF-containing ART is associated with an increase in BMI and body weight in ART-experienced patients. Two study groups were established: 32 patients who switched from TDF to TAF only and 68 patients who switched from TDF to TAF along with changes to other components of the ART regimen. Significant weight gain and BMI increase was observed during the first year after initiation of TAF-containing ART regimens in both groups (mean change +1.91 kg and +0.61 kg/m2 in the first group and +1.50 kg and +0.49 kg/m in the second group). During the second year of TAF-based treatment, a sustained trend of body weight and BMI increase was noted only in the second group (mean change +1.46 kg, + 0.46 kg/m). Analysis of body weight changes in certain subpopulations from the second group (selected based on patients' baseline characteristics) revealed a significant weight gain within two years after the switch in patients over 50 years old and in those whose ART had lasted longer than 10 years. These findings suggest that a possible impact of TAF on weight gain should be taken into account when selecting ART components, especially in older patients or those with a long history of antiretroviral treatment.