Abstract Background Weight gain and obesity among people with HIV (PWH) is an ongoing concern and has been associated in some studies with integrase strand transfer inhibitor (INSTI) antiretroviral (ART) medications. We sought to investigate body mass index (BMI) changes among PWH initiating INSTI vs non-INSTI regimens using the nationwide TriNetX database.Table 1:Baseline CharacteristicsTable 2:Change in Body Mass Index; Adjusted Model Methods TriNetX is a database of electronic medical record data abstracted from over 50 US institutions. Demographic, clinical, and laboratory data were assessed for treatment naive PWH ( =18y) with available BMI measurements 30 days from and closest to 12m post ART initiation. We excluded those who switched between INSTI and non-INSTI regimens during follow-up, had mixed-anchor regimens or missing/mishandled data. Bivariate and multivariable generalized linear models were used to assess potential associations between INSTI use and changes in continuous BMI and weight Results 5754 PWH were included (Table 1); 75.7% male (N=4357) and 42.1% Black (N=2422). Median BMI at ART initiation was 24.2 kg/m2 (IQR 21.4-28.2) and median follow-up BMI was 25.5 kg/m2 (IQR 22.3-29.8). INSTI (n=4347) and non-INSTI (n=1407) groups differed on median year of ART initiation, median duration of follow-up, median CD4 count at initiation, TAF use and TDF use with some variations in regionality (Table 1). INSTI use was associated with a statistically significant increase in BMI (+0.41kg/m2; 95% CI 0.14,0.68, p=0.003) compared to non-INSTIs however no change in BMI category was observed when adjusting for covariates (Table 2). Increased BMI was also associated with baseline BMI, sex, follow-up duration, TAF use, CD4 count at initiation and region. Weight increase for the INSTI group was 6.3% (IQR -0.6-11.7) vs 3.7% (IQR -2.7-8.8) for non-INSTIs. Conclusion INSTI use, sex, follow-up duration, and TAF use were associated with small increases in BMI, whereas TDF, EFV, baseline BMI and baseline CD4 were all associated with no change in or decreased BMI, indicating that changes in body weight are multifactorial. Future studies will compare BMI trends to non-HIV populations in order to further factors contributing to weight gain in PWH. Disclosures Ivania Rizo, MD, NovoNordisk: Advisor/Consultant Archana Asundi, MD, DayZero Diagnostics: Grant/Research Support|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Grant/Research Support|Theratechnologies: Grant/Research Support|Viiv Healthcare: Grant/Research Support
Schmidt et al. (2026) studied this question.