Background: Our objective was to determine virological and clinical characteristics associated with virological failure in human immunodeficiency virus (HIV)-infected patients switching to darunavir/ritonavir (DRV/r) monotherapy.
Methods: The main outcome was virologic rebound, defined as 2 consecutive measurements of HIV-1 plasma RNA viral load (VL) >50 copies/mL. A logistic model was used to investigate which variables were predictive of a virologic rebound at weeks 48 (W48) and 96 (W96).
Results: Receiving DRV/r monotherapy was associated with virologic rebound at W48 (P = .016) and W96 (P = .002), comparable to triple therapy. In the DRV/r monotherapy group, at W48, having a VL >50 copies/mL at day 0 and even a baseline ultrasensitive VL >1 copy/mL were predictive factors to virologic rebound (P = .042 and P = .025, respectively). At W96, shorter time of prior antiretrovial therapy (ART) exposure (odds ratio [OR] = 2.93 per 5 years decrease; P = .006), higher HIV-1 DNA at day 0 (OR = 2.66 per 1 log(10) copies/10(6) cells increase; P = .04) and adherence <100% (OR = 3.84 vs 100%; P = .02) were associated with an increased risk of rebound.
Conclusions: Factors associated with virological failure in patients receiving DRV/r monotherapy were having an initial blip, shorter time of antiretroviral treatment before monotherapy, and an adherence <100% during monotherapy. The importance of prior duration exposure to ART was in agreement with the impact of HIV-1 blood reservoir and VL level at baseline.