979. BMI and ASCVD Risk Score Changes in Virologically Suppressed Patients with HIV Switching from TDF to TAF Containing ART

BACKGROUND: Switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) containing antiretroviral therapy (ART) can preserve or improve renal function as well as bone mineral density in patients living with HIV infection (PLWH). The switch can also negatively influence cholesterol, but potential changes in body mass index (BMI) and atherosclerotic cardiovascular disease (ASCVD) risk are unknown. METHODS: This retrospective observational study evaluated BMI and ASCVD risk score changes in virologically suppressed PLWH who switched from TDF to TAF without switching any other ART regimen components. Adult patients on TDF for ≥1 year with two consecutive HIV viral loads <200 copies/mL in the year prior to a TAF switch were included. Bodyweight, BMI, cholesterol, ASCVD risk score, and other variables were collected for the year prior to and following the switch. The unadjusted distributions of pre- and post-switch values were compared with the Wilcoxon signed-rank test. Repeated-measures generalized estimating equations were constructed to evaluate changes in BMI and ASCVD risk scores associated with TDF to TAF switches. These were adjusted for predictors retained in the model if their P-values were <0.05. ASCVD risk scores were skewed right, so those data were log-transformed prior to modeling. RESULTS: A total of 110 patients met the criteria and were included for analysis (Table 1). In unadjusted analyses, there were significant increases in weight, BMI, total cholesterol, LDL, HDL, and ASCVD score in the year after switching from TDF to TAF (each P ≤ 0.01, Table 2). Only gender was retained in the adjusted BMI model, which suggested switching from TDF to TAF lead to an increase of 0.45 kg/m(2) in the expected mean for BMI (95% CI: 0.14, 0.76). Age, gender, race, concomitant medications that can cause weight gain, and time since HIV diagnosis were retained as covariates in the adjusted ASCVD model. This model suggested that switching from TDF to TAF was associated with a 13% increase in the expected mean for ASCVD risk score (95% CI: 4%, 23%). CONCLUSION: We observed significant increases in BMI and ASCVD risk in PLWH 1 year following a switch from TDF to TAF without changes in other ART regimen components. The mechanism of these metabolic changes is unclear and requires further study. [Image: see text] [Image: see text] DISCLOSURES: All Authors: No reported Disclosures.