Quantification of human immunodeficiency virus type 1 p24 antigen and antibody rivals human immunodeficiency virus type 1 RNA and CD4+ enumeration for prognosis. National Institute of Child Health and Human Development Intravenous Immunoglobulin Clinical Trial Study Group

Abstract

Background: The sensitivity, specificity and positive predictive value of baseline serum concentrations of HIV-1 immune complex-dissociated (ICD) p24 antigen for predicting disease progression and mortality were assessed and compared with results obtained for HIV-1 ICD p24 antigen with HIV-1 p24 antibody and for HIV-1 RNA with CD4+ lymphocyte percent.

Methods: Data from HIV-infected children enrolled in a North American clinical trial (National Institute of Child Health and Human Development Intravenous Immunoglobulin Clinical Trial) were analyzed. Disease progression was defined as growth failure, CD4+ lymphocyte percent decline to <15% after study entry or development of an AIDS-defining opportunistic infection.

Results: Baseline samples were available for ICD p24 antigen testing (median concentration, 319 pg/ml; range, <50 to 15,640) in 240 children. The combination of detectable ICD p24 antigen and low p24 antibody was more sensitive but less specific than the combination of high HIV-1 RNA and low CD4+ lymphocyte percent in predicting disease progression and mortality. Using receiver operating characteristic curves, the specificity of ICD p24 antigen with p24 antibody for classifying children's disease progression or mortality was as great as, or greater than, HIV-1 RNA with CD4+ lymphocyte percent at points on the curve corresponding to higher sensitivity.

Conclusions: The use of ICD p24 antigen with p24 antibody to identify children at high risk of disease progression or mortality could be a viable alternative to the more expensive and technically difficult HIV-1 RNA and CD4+ lymphocyte assays in resource-poor settings, including developing countries where the majority of children with HIV-1 infection reside.