Background: Once-daily, single-tablet regimens (STRs) have been associated with improved patient outcomes compared to multi-tablet regimens (MTRs). This study evaluated real world adherence and persistence of HIV antiretroviral therapy (ART), comparing STRs and MTRs.

Methods: Adult Medicaid beneficiaries (aged ≥ 18 years) initiating ART with ≥ 2 ART claims during the identification period (January 1, 2015-December 31, 2016) and continuous health plan enrollment for a 12-month baseline period were included. For STRs, the first ART claim date was defined as the index date; for MTRs, the prescription fill claim date for the last drug in the regimen was defined as the index date, and prescription fills were required to occur within a 5-day window. Adherence was assessed in 30-day intervals over a 6-month period, with adherence defined as having less than a 5-day gap between fills. Persistence was evaluated as median number of days on therapy and percent persistence at 12 months. Cox Proportional Hazard models were used to evaluate risk of discontinuation, controlling for baseline and clinical characteristics.

Results: A total of 1,744 (STR = 1290; MTR = 454) and 2409 (STR = 1782; MTR = 627) patients newly prescribed ART had available data concerning adherence and persistence, respectively. Average age ranged 40-42 years. The patient population was predominantly male. Adherence assessments showed 22.7% of STR initiators were adherent to their index regimens over a 6-month period compared to 11.7% of MTR initiators. Unadjusted persistence analysis showed 36.3% of STR initiators discontinued first-line therapy compared to 48.8% for MTR initiators over the 2-year study period. Controlling for baseline demographic and clinical characteristics, MTR initiators had a higher risk of treatment discontinuation (hazard ratio [HR] = 1.6, p < 0.0001). Among STRs, compared to the referent elvitegravir (EVG)/cobicistat (COBI)/emtricitabine (FTC)/tenofovir alafenamide (TAF), risk of discontinuation was higher for efavirenz (EFV)/FTC/tenofovir disoproxil fumarate(TDF) (HR = 3.6, p < 0.0001), EVG/COBI/FTC/TDF (HR = 2.8, p < 0.0001), and abacavir (ABC)/lamivudine (3TC)/dolutegravir (DTG) (HR = 1.8, p = 0.004). Among backbones, FTC/TAF was associated with lower risk of discontinuation than FTC/TDF (HR = 4.4, p < 0.0001) and ABC/3TC (HR = 2.2, p < 0.0001).

Conclusions: Among patients newly prescribed ART, STR initiators were significantly less likely to discontinue therapy and had greater adherence and persistence compared to MTR initiators. Regimens containing FTC/TAF as a backbone had higher persistence than those consisting of other backbones.