A Critical Assessment of the Prognostic Value of HIV-1 RNA Levels and CD4+ Cell Counts in HIV-Infected Patients

Abstract

VARIOUS BIOLOGICAL parameters predict clinical outcomes in patients infected with the human immunodeficiency virus type 1 (HIV-1). Until 1995, CD4⁺ cell counts were considered to be the best predictor, but several recent studies suggest that a direct measurement of viremia (plasma HIV-1 RNA) may provide superior prognostic information.^1-12 However, currently available evidence presents some limitations, which we sought to address in this study. First, previous studies have involved selected patient populations: patients enrolled in clinical trials of antiviral treatments,^7-12 asymptomatic patients recently infected with HIV-1,^1,2 or patients with hemophilia.⁴ Whether these results apply to HIV-infected patients encountered in general medical practice, in particular to those with advanced immunosuppression, is therefore uncertain. Second, most previous studies have focused on viremia, and treated other predictors, including CD4⁺ cell counts, as confounders. Little information is available on the respective contribution of each variable, and on the interaction between viremia and CD4⁺ cell counts in predicting clinical outcomes. Last, few studies^3-6 have examined separately the risk of death and the risk of clinical progression; predictors may vary for these 2 outcomes.