Objective: To compare HIV-disease progression according to changes of plasma HIV RNA observed in the year following initiation of a new antiretroviral treatment.
Design: Prospective cohort treated with two nucleoside analogues or a triple combination including a protease inhibitor.
Methods: A Cox model was used to estimate the effect of viral response during the first year after initiation of treatment on the subsequent occurrence of new AIDS-defining events or death. Viral response was fitted either as HIV RNA reduction during the initial 4-12 months of treatment or reduction during the first month.
Results: Among 773 patients (47% with triple drug combination) followed for a median period of 27 months, 62 patients experienced a clinical event. Poor viral responders (at least two measurements > 3.7 log10 copies/ml during 4-12 months of treatment) had a higher risk of disease progression than good responders (RNA < 2.7 log10 copies/ml) after adjustment [hazard ratio (HR), 2.24; 95% confidence interval (CI), 1.1 7-4.29]. Intermediate responders (2.7 < or = RNA < or = 3.7 log10 copies/ml) had a risk of progression comparable with that of good responders (HR, 1.43; 95% CI, 0.64-3.22). A large initial viral reduction was also a protective factor for clinical progression (HR, 0.51 for 1 log10 copies/ml increase of the reduction; 95% CI, 0.31-0.85) and was associated with the viral response during the subsequent 4-12 month period. No patient with a reduction < 0.5 log10 copies/ml in the first month was classified as a good responder in the subsequent 4-12 month period (P < 0.01).
Conclusions: A sustained HIV RNA > 3.7 log10 copies/ml should suggest a prompt change of treatment. When the reduction in HIV RNA is < 0.5 log10 after 1 month of treatment, this action should be anticipated. A sustained HIV RNA level between 2.7 and 3.7 log10 copies/ml may permit the deferral of a change of drug regimen according to the patient's history and therapeutic options.