Antiretroviral Therapy and Efficacy After Virologic Failure on First-line Boosted Protease

Background. Virologic failure (VF) on a first-line ritonavir-boosted protease inhibitor (PI/r) regimen is associ-ated with low rates of resistance, but optimal management after failure is unknown. Methods. The analysis included participants in randomized trials who experienced VF on a first-line regimen of PI/r plus 2 nucleoside reverse transcriptase inhibitors (NRTIs) and had at least 24 weeks of follow-up after VF. Antiretroviral management and virologic suppression (human immunodeficiency virus type 1 [HIV-1] RNA <400 copies/mL) after VF were assessed. Results. Of 209 participants, only 1 participant had major PI-associated treatment-emergent mutations at first-line VF. The most common treatment approach after VF (66%) was to continue the same regimen. The virologic suppression rate 24 weeks after VF was 64 % for these participants, compared with 72 % for those who changed reg-imens (P =.19). Participants remaining on the same regimen had lower NRTI resistance rates (11 % vs 30%; P =.003) and higher CD4+ cell counts (median, 275 vs 213 cells/µL; P =.005) at VF than those who changed. Among partic-ipants remaining on their first-line regimen, factors at or before VF significantly associated with subsequent virologic suppression were achieving HIV-1 RNA <400 copies/mL before VF (odds ratio [OR], 3.39 [95 % confidence interva