Response to: “Assessment of Baseline HIV Viral Load as a Risk Factor for Loss of Virologic Suppression in Protease Inhibitor-Based Monotherapy Trials”

Abstract

To the Editors: We appreciate the comments from Papastamopoulos et al about the possible role of baseline viral load as a predictive factor of the success of lopinavir-ritonavir monotherapy. In this context, the word “baseline” might be confusing because, in the OK04 trial, at baseline, all patients had suppression of viral replication. “Pre-HAART” (highly active antiretroviral therapy) viral load is probably a more precise term than “baseline” in a trial of boosted protease inhibitor monotherapy for maintenance of HIV viral suppression. We have carefully looked at risk factors for loss of virologic suppression in patients receiving lopinavir/ritonavir monotherapy for maintenance of HIV suppression in the OK trials.1 We have used a Cox proportional hazard model that included the following variables: age, sex, route of HIV-1 infection, previous AIDS diagnosis, viral load before starting HAART, baseline CD4+ T-cell count, nadir CD4+ T-cell count, duration of virologic suppression while on HAART before monotherapy, duration of HAART before monotherapy, baseline hemoglobin, use of lopinavir-ritonavir as the first protease inhibitor, medication adherence, baseline total cholesterol, baseline triglycerides, and high-density lipoprotein cholesterol. With use of this model, the only independent variables associated with loss of virologic suppression were two or more visits with self-reported missed doses in the week before the study visit, a lower baseline hemoglobin, and a nadir CD4+ T-cell count less than 100 cells/μL. Pre-HAART viral load (analyzed as a continuous variable) was not independently associated with failure of lopinavir-ritonavir monotherapy (hazard ratio per 1 log10 copies/mL increase: 1.5, confidence interval 95% 0.67-3.34; P = 0.32). Similar findings have been reported by other authors.2 Jose R. Arribas, MD* Federico Pulido, MD† *Hospital La Paz, HIV Unit †Hospital Doce de Octubre, HIV Unit Madrid, Spain