Background:
Both B/F/TAF and DTG/3TC are recommended in treatment guidelines for both initial and switch therapy in people with HIV (PWH). Understanding clinical and socio-demographic drivers of switching to DTG/3TC or B/F/TAF and how PWH vary by regimen is critical when comparing outcomes.
Methods:
Retrospective study with Trio Health HIV Network EMR data. Eligibility: ≥18 yrs, switched to B/F/TAF or DTG/3TC after DTG/3TC approval (4/2019-6/2022). Baseline (BL) characteristics were compared (Χ-square, t-test). Logistic regression (LR) predicted probability of prescribing/dispensing DTG/3TC (propensity scores; PS) given BL characteristics. Classification regression trees (CRT) and LR identified primary predictors of prescribing/dispensing DTG/3TC. All shown comparisons were significant (p< .05).
Results:
Of 6996 PWH, 1112 (16%) were prescribed DTG/3TC. PWH prescribed DTG/3TC differed in key characteristics: age ≥50 yrs (49 vs 38% B/F/TAF), commercial payer (57 vs 45%), BL viral suppression (VS < 200 copies/ml; 94 vs 92%), CD4 >200 cells/mm3 (84 vs 66%), eGFR < 60 mL/min/1.73m2 (15 vs 6%), prior INSTI use (59 vs 36%), obese (BMI > 30 kg/m2; 32 vs 26%), hyperlipidemia (32 vs 28%), hypertension (34 vs 25%), osteoporosis (4 vs 2%), renal disease (10 vs 3%), alcohol (4 vs 6%), or substance use (5 vs 10%). Similar results were observed in the subset with dispensing data (n=3946; 13% DTG/3TC). The PS distribution [Fig.] for DTG/3TC was shifted right, with distinct tails for DTG/3TC (right) and B/F/TAF (left), where the probability of the alternate regimen was lower based on BL characteristics.For DTG/3TC (vs B/F/TAF), CRT and LR identified primary prescribing predictors: prior INSTI (odds ratio [OR]=2.4), CD4 >200 (OR=2.7), eGFR< 60 (OR=2.2), no substance use (OR=2.8), payer (Commercial vs Medicare OR=1.4). Payer was the primary predictor of DTG/3TC dispensing (followed by hyperlipidemia, CD4, prior INSTI).
Conclusions:
Baseline characteristics of PWH switching to DTG/3TC vs B/F/TAF were significantly different. B/F/TAF prescription was associated with factors that reflect HIV clinical parameters and adherence (e.g., VS, CD4< 200, substance use). By contrast, prescribing DTG/3TC was associated with renal toxicity and obesity. The results argue that although they are both guideline-recommended regimens, clinicians do not perceive them as equally appropriate for all patients. Accounting for channeling bias in observational studies evaluating outcomes is essential for interpreting differences between regimens.
Figure. Distribution of Propensity Scores.