BACKGROUND: Previously, we demonstrated that switching to a bictegravir (BIC) vs. DTG-based regimen (DBR) was associated with lower annualized weight gain of a similar magnitude post-switch at Week 48. Here, we report updated changes in weight and BMI through 96 weeks compared to 2 years prior to switch.
METHODS: Data on demographics, clinical characteristics, weight, and BMI are collected from virologically suppressed adults switched to BIC/emtricitabine(F)/tenofovir alafenamide (TAF), DTG+ F/TAF, DTG/abacavir (ABC)/lamivudine (3TC), DTG/rilpivirine (RPV) and DTG/3TC 2 years prior to switch through 144 weeks post-switch. Linear spline models were fit to estimate and compare the trajectories of weight and BMI changes observed pre-and-post-switch. Adjusted piecewise linear mixed-effects models were fit to examine factors associated with weight and BMI change pre-and-post-switch.
RESULTS: Baseline demographic and clinical characteristics have been previously reported. 673 switched to BIC/F/TAF, 148 switched to DTG + F/TAF, 51 switched to DTG/ABC/3TC, 48 switched to DTG/RPV and 36 switched to DTG/3TC. At Week 96, switching to BIC/F/TAF vs. a DBR (grouped) was associated with lower annualized weight gain post-switch (-0.75 kg/year vs. -0.37 kg/year respectively, p=0.336). DTG/3TC switches continued to have the highest annualized weight gain (0.66 kg/year, 95% confidence interval [CI]: -0.6, 1.92), whereas DTG/RPV switches had the lowest annualized weight gain (-2.68 kg/year, 95% CI: -4.61, -0.73) post-switch at Week 96. DTG/RPV and BIC/F/TAF switches were the only groups with significantly lower annualized weight gain post-switch compared to pre-switch trajectories at Week 96. Similar trends were observed for BMI changes. Baseline BMI<18.5 kg/m2 was the only evaluated factor associated with significantly higher annualized weight gain post-switch, whereas multiple factors were associated with significantly lower annualized weight gain, but among them referral to the internal wellness clinic and baseline CD4+ T-cell count<200 cells/mm3 were associated with the lowest annualized weight gain post-switch.
CONCLUSIONS: At Week 96, switching to a BIC vs. DBR continued to be associated with lower annualized weight gain of a similar magnitude post-switch. Weight and BMI changes stabilized for many groups at Week 96; however, switching to BIC/F/TAF and DTG/RPV was associated with significantly lower annualized weight gain post-switch.