Value of quantification of p24 antigen in plasma as a prognostic marker of survival in a cohort of 251 HIV-positive patients

OBJECTIVE: To analyse plasma p24 antigen as a marker of survival in a cohort of HIV-infected patients whose time of seroconversion is unknown. DESIGN: Prospective cohort study. SETTING: AIDS Unit in a teaching hospital. PATIENTS: 251 patients were studied, most on antiretroviral therapy. Mean initial CD4 cell counts were 376 x 106/ 1 (range: 0.8-1350). 51 cases had been diagnosed previously with AIDS. METHODS: Analysis of survival, according to initial plasma p24 antigen was performed by Kaplan-Meier test. Relative risks were calculated by Cox's proportional hazards model. RESULTS: During a follow-up period of 24 months, 46 patients died. Relative risk (RR) of death related to the group with p24 antigen = < 40 pg/ml was 3.32 when p24 antigen > 40 pg/ml (p = 0.0001). CD4+ cell levels adjusting, the result was 2.47 (CI 95% 1.37-4.46) (p = 0.0027). CONCLUSIONS: Plasma levels of p24 antigen is useful as a marker of the risk of death and it behaves as a independent prognostic marker in our patients. P24 antigen = < 40 pg/ml is associated with a better prognosis.