Variability and Prognostic Values of Virologic and CD4 Cell Measures in Human Immunodeficiency Virus Type 1–Infected Patients with 200–500 CD4

Virologic measurements are increasingly used to evaluate prognosis and treatment responses in human immunodeficiency virus (HIV) type 1 infection. Markers of HIV-1 replication, including infectious HIV-1 titer from peripheral blood mononuclear cells, serum HIV-1 p24 antigen, plasma HIV-1 RNA, CD4 cell numbers, and viral syncytium-inducing (SI) phenotype, were determined in 391 virology substudy participants in AIDS Clinical Trials Group study 175. The subjects had 200– 500 CD4 cells/mm3. All markers of viral replication significantly correlated with one another and were inversely related to CD4 cell number. Disease progression to an AIDS-defining event or death or loss of 50 % of CD4 cells was associated with infectious HIV-1 titer (P .001), HIV-1 RNA (P .001), and HIV-1 p24 antigen (P .007). In multivariate proportional hazards models, p24 antigen was never significant when HIV-1 RNA level was included. In a model containing infectiou