LAUSR

OBJECTIVE To assess the use of two-drug antiretroviral regimens (2DR) and virologic and immunologic outcomes compared to three-drug regimens (3DR) in the EuroSIDA cohort. DESIGN Multicentre, prospective cohort study. METHODS Logistic regression was used to analyse the uptake and outcomes among HIV-positive individuals who started or switched to a 2DR compared to those on a 3DR. Virologic outcomes were assessed on-treatment as the proportion of individuals with controlled viral load (VL, <400 copies/mL), or with a composite modified FDA snapshot endpoint (mFDA), with mFDA success defined as controlled VL at 6- or 12-months for individuals with a known VL, no regimen changes, AIDS or death. Immunologic response was defined as a 100 cells/μL or a 25% increase in CD4 counts from baseline. RESULTS Between 1/7/2010-31/12/2016, 423 individuals started or switched to a 2DR (8 antiretroviral-naïve) and 4347 started a 3DR (566 naïve). Individuals on 2DR tended to have suppressed VL, higher CD4 cell counts and more comorbidities at baseline compared to those on 3DR. There were no differences in the proportions of individuals who obtained on-treatment or mFDA success, and no significant differences in the adjusted odds ratios for mFDA success or immunologic responses between the 2DR and 3DR groups at 6- or 12-months. CONCLUSION In routine clinical practice, 2DR were largely used for virologically suppressed individuals with higher cumulative exposure to ARVs and comorbidities. Virologic and immunologic outcomes were similar among those on 2DR or 3DR, although confounding by indication cannot be fully excluded due to the observational nature of the study.