The Incidence and Severity of Drug Interactions Before and After Antiretroviral Therapy Simplification in Treatment-Experienced Patients With HIV Infection

Background: Current guidelines advocate for antiretroviral therapy (ART) simplification in patients on complicated regimens. Simplifying ART improves patient adherence and quality of life, but changes in drug interactions (DIs) are uncertain. Objective: This study assessed changes in DIs following ART simplification in patients with HIV. Methods: This was an observational, retrospective cohort study of patients attending an urban HIV clinic. Patients were included if they had ART simplification (a decreased number of daily tablets) and ≥1 concomitant medication (CM). Total DI scores were generated for each patient pre–ART simplification and post–ART simplification using an online DI database. Each ART-CM pair labeled as “do not co-administer” was given a score of 2, “potential interaction” a score of 1, or “no interaction” a score of 0. Differences in total DI scores following simplification were analyzed with a Wilcoxon Signed-Rank test. Predictors of DI score reductions were examined with linear regression. Results: A total of 99 patients were included. Their median age was 54 years, and 79% were male. The median durations of HIV infection and ART were 16 and 10 years, respectively. Patients were receiving an average of 4.5 CMs. Median interaction scores presimplification and postsimplification were 3 (interquartile range [IQR], 1-6) and 1 (IQR, 0-2) respectively ( P < 0.001). Predictors of score reductions were the patient’s number of CMs, discontinuing a protease inhibitor, and switching to a dolutegravir-based regimen. Conclusion and Relevance: ART simplification decreased the incidence of DIs in this analysis of patients with advanced age who had ART experience and polypharmacy.