Real world effectiveness of standard of care triple therapy versus two-drug combinations for treatment of people living with HIV

BACKGROUND: Since 1996, the standard of care (SOC) therapy for HIV treatment has consisted of a backbone of two nucleoside analogue reverse transcriptase inhibitors (NRTI) paired with a third agent. Use of two-drug combinations (2DC) has been considered for selected patients to avoid toxicities associated with the use of NRTIs. This study aimed to compare the real-world outcomes of integrase strand transfer inhibitor (INSTI)-containing triple therapy (TT) to dolutegravir- (DTG) and/or boosted protease inhibitor (bPI)-based 2DC in a large Spanish cohort of HIV patients. METHODS: A retrospective analysis was performed using data from the VACH cohort, a prospective multicentre Spanish cohort of adult HIV patients. All treatment experienced patients initiating a TT of an INSTI combined with two NRTIs or a 2DC-containing DTG and/or a bPI between 01/01/2012 and 01/06/2017 were included. The unit of analysis was patient-regimens. The overall sample analysis was complemented with two sub-analyses. The first sub-analysis focused on patients treated with a backbone plus DTG compared to those treated with DTG+ one other antiretroviral. The second sub-analysis focused on patients with HIV RNA<50 copies/mL at baseline, irrespective of the regimen used. The following endpoints were assessed: time to discontinuation for any reason, time to switch due to virologic failure, and time to switch due to toxicity (reasons for discontinuation according to clinician report in the database). Time-to-event analyses were conducted using Kaplan–Meier survival curves and Cox regression models. RESULTS: Overall 7,481 patients were included in the analysis, contributing to 9,243 patient-regimens. Patient characteristics at baseline differed among groups, with the 2DC group being significantly older and having a higher proportion of women, a longer time on ART and a higher number of previous virologic failures. Median (95% Confidence Interval [C.I.]) time to switch was 2.5 years (2.3, 2.7) in 2DC group versus 2.9 years (2.7, 3.0) in TT. Adjusted hazard ratios (95% C.I.) for discontinuation due to any reason, virologic failure and toxicity in the 2DC vs TT group were 1.29 (1.15; 1.44), 2.06 (1.54; 2.77) and 1.18 (0.94; 1.48), respectively. Results were consistent in the two sub-analyses. CONCLUSION: In this analysis, time to discontinuation and probability of remaining free of virologic failure were significantly higher in patients on INSTI-based TT compared to DTG- and/or bPI-containing 2DC, with no differences in toxicity.