Plasma HIV-1 RNA detection below 50 copies/mL and risk of virologic rebound in patients receiving highly active antiretroviral therapy

Background. Plasma human immunodeficiency virus type 1 (HIV-1) RNA suppression <50 copies/mL is regarded as the optimal outcome of highly active antiretroviral therapy (HAART). Current viral load (VL) assays show increased sensitivity, but the significance of RNA detection <50 copies/mL is unclear. Methods. This study investigated the virologic outcomes of 1247 patients with VL <50 copies/mL at an arbitrary time point during HAART (=T0), according to whether the actual, unreported T0VL was 40-49 copies/mL, RNA detected <40 copies/mL (RNA +), or RNA not detected (RNA -), as measured by the Abbott Real Time assay. Predictors of rebound >50 and >400 copies/mL over 12 months following T0 were analyzed with Cox proportional hazards models incorporating the T0VL and demographic and clinical data. Results. Rebound rates >50 copies/mL were 34.2% for T0VL 40-49 copies/mL, 11.3% for RNA +, and 4.0% for RNA -; rebound rates >400 copies/mL were 13.0%, 3.8%, and 1.2%, respectively. The adjusted hazard ratios for rebound >50 copies/mL were 4.67 (95% confidence interval, 2.91-7.47; P<.0001) and 1.97 (1.25-3.11; P<.0001) with T0VL 40-49 copies/mL and RNA +, respectively, relative to RNA -, and 6.91 (2.90-16.47; P<.0001) and 2.88 (1.24-6.69; P<.0001), respectively, for rebound >400 copies/mL. The association was independent of adherence levels.Conclusions.In treated patients monitored by RealTime, a VL of 40-49 copies/mL and, to a lesser extent, RNA detection <40 copies/mL predict rebound >50 and >400 copies/mL independently of other recognized determinants. The goal of HAART may need to be revised to a lower cutoff than 50 copies/mL