People with HIV Continuing on Complex Regimens in the Era of Treatment Optimization: Characteristics and Outcomes.

While once-daily single-tablet regimens (STRs) are recommended for most people with human immunodeficiency virus (HIV; PWH), some require complex antiretroviral (ARV) regimens due to resistance, contraindications, or drug-drug interactions. We characterized PWH who were virologically suppressed on complex regimens (VS on CR) in a U.S. cohort to inform treatment optimization as new switch options emerge. This retrospective study analyzed electronic medical records from the Trio Health HIV Network and genotypic resistance data from Labcorp. We included PWH ≥ 18 years who were virologically suppressed (viral load [VL] < 200 copies/mL) at complex regimen initiation between January 2016 and November 2023, with ≥6 months from last prescription and ≥1 year of follow-up. Complex regimens included ≥2 of 3 core ARV classes concomitantly, more than once-daily dosing, multi-tablet regimens (MTRs) not replaceable by STRs, or resistance to two ARV classes. Virologic failure (VF) was defined as VL ≥ 500 copies/mL or two consecutive VLs ≥ 200 copies/mL. PWH on ibalizumab, fostemsavir, or lenacapavir were excluded to reflect standard clinical practice. Of 43,236 PWH with ARV prescriptions, 3,320 (8%) were VS on CR. Among these, 69% were on MTRs, 43% used ≥2 core ARV classes, and 11% had resistance to two classes. The median age was 52 years, and 77% were male. Common comorbidities included obesity (69%), neuropsychiatric disorders (35%), and cardiovascular disease (33%). Regimens predominantly included protease inhibitors (77%), nucleoside reverse transcriptase inhibitors (75%), and integrase strand transfer inhibitors (57%). Over a median 2.2-year follow-up, 4% experienced VF. Approximately 8% of PWH on ART remain VS on CR, underscoring the need for education on regimen optimization and novel treatment options for those unable to simplify their therapy.