Antiretroviral Regimen Durability and Success in Treatment-Naive and Treatment-Experienced Patients by Year of Treatment Initiation, United States, 1996-2011

Background: Although modern combination antiretroviral therapy (cART) regimens are better tolerated and less complex than earlier treatments, regimen modification or discontinuation remains a concern. Methods: We studied HIV Outpatient Study (HOPS) participants who initiated the first or second cART regimens during: 1996-1999, 2000-2003, 2004-2007, and 2008-2011. We analyzed regimen durability (time to regimen modification) and success (achieving undetectable plasma HIV RNA) for the first and second cART regimens using Kaplan-Meier curves and log-rank tests, and examined factors associated with durability and success of the first cART regimen using proportional hazards models. Results: Durability of cART was progressively longer for cART regimens initiated in more recent periods: median first cART regimen durations were 1.0, 1.1, 2.1, and 4.6 years in 1996-1999, 2000-2003, 2004-2007, and 2008-2011, and the median second cART durations were 0.9, 1.2, 2.8, and 3.9 years, respectively (both P < 0.001). Comparing 1996-1999 and 2008-2011, the percentage of patients who achieved an undetectable HIV RNA within 6 months of first cART initiation increased from 65% to 81% and from 63% to 80% on second cART (both P < 0.001). Among patients initiating first cART during 2008-2011, black non-Hispanic/Latino race/ethnicity and ≥twice-daily dosing were significantly associated with higher rates of regimen modification (P < 0.05), and higher baseline HIV RNA levels were associated with failure to achieve an undetectable HIV RNA (P < 0.001). Conclusions: Among HIV-infected U.S. adults in routine HIV care, durability of the first and second cART regimens and the likelihood of prompt virological suppression increased during 1996-2011, coincident with the availability of more tolerable, less complex cART options.