Regimen complexity can adversely affect adherence, leading to virologic failure. It is unknown whether this occurs with regimens that contain the second-generation integrase inhibitors (INSTIs), bictegravir and dolutegravir, both of which are recommended in the current DHHS Guidelines.
EMR, prescription and dispensing data for 2,217 patients initiating BIC/FTC/TAF, DTG/ABC/3TC, DTG+TDF/FTC, or DTG+TAF/FTC between Aug 2013 – Aug 2019 were collected from 5 practices across 17 US states. Only those without prior documented treatment with DTG or BIC, respectively, were included. Adherence was defined as proportion of days covered through the first 6 months of regimen treatment. To determine treatment effects on adherence, we (1) used multiple imputation with predictive posterior matching to account for incomplete baseline measures, (2) used mixed effects logistic regression, using BIC/FTC/TAF vs DTG-regimens with random intercept for practice, to adjust for heterogeneity between practices, (3) adjusted models using demographics and relevant baseline clinical data (CD4 count, viral load, AST, ALT, lipids, eGFR, hemoglobin A1C) and year of regimen initiation, and (4) employed propensity score matching using imputed baseline labs and demographics, allowing for squares and first order interactions between all included predictors. In addition to adherence, we assessed viral suppression (<200 copies/mL) in a subset of 655 patients at 6 months (measured within 1 week prior and up to two months after).
In observed (unadjusted) data, adherence was significantly greater at 6 months to BIC/FTC/TAF compared to any dolutegravir-regimen and to DTG/ABC/3TC in comparison to DTG+TDF/FTC or DTG+TAF/FTC at the 80% level [TABLE]. After controlling for non-treatment effects, adherence was only significantly different for BIC/FTC/TAF compared to DTG+TDF/FTC or DTG+TAF/FTC (p<0.01). Assessment of viral suppression at 6 months for patients with measures (n=655) was favorably impacted by adherence ≥80% (OR 2.27 [1.26-4.07] p<0.01) and ≥95% (OR 2.63 [1.55-4.48] p<0.01).
This study of bictegravir and dolutegravir-based regimens supports the notion that simplifying treatment to a single tablet aids in adherence, and that adherence yields improved virologic outcomes in clinical settings.