VARIABILITY AND PROGNOSTIC VALUES OF VIROLOGICAL AND CD4 CELL MEASURES IN HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1-INFECTED PATIENTS WITH 200-500 CD4 CELLS MM(3) (ACTG-175)/

Virologic measurements are increasingly used to evaluate prognosis and treatment responses in human immunodeficiency virus (HIV) type I infe ction. Markers of HIV-1 replication, including infectious HIV-1 titer from peripheral blood mononuclear cells, serum HIV-1 p24 antigen, plas ma HIV-1 RNA, CD4 cell numbers, and viral syncytium-inducing (SI) phen otype, were determined in 391 virology substudy participants in AIDS C linical Trials Group study 175. The subjects had 200-500 CD4 cells/mm( 3), All markers of viral replication significantly correlated with one another and were inversely related to CD4 cell number. Disease progre ssion 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 infectious HIV-1 titer (P = .038) , HIV-1 RNA (P < .001), SI phenotype (P < .001), and CD4 cell number ( P = .18), only the virologic parameters remained significantly associa ted with progression.