RESUMEN
BACKGROUND: Prospective study of survival and AIDS or death progression in a cohort of 251 HIV infected patients whose seroconversion time is unknown, with 1 main objective: To analyse CD4+ lymphocytes count, p24 antigen plasmatic levels and viral load as surrogate markers. PATIENTS AND METHODS: 251 patients were included, most of them undergoing antiretroviral therapy, followed consecutively in the HIV/AIDS Unity of Internal Medicine Service of the Hospital Universitario Arnau de Vilanova in Lleida. We made clinical and analytical baseline studies and every 3 months thereafter. In relation to CD4+ lymphocytes, 3 groups were established: group I, 500 or more cells/mL; group II, 200-499 cells/mL and group III, < 200 cells/mL. In the same way, with p24 antigen we established 3 group: group I, < 20 pg/mL, group II, 20-39 pg/mL, group III 40 or more pg/mL. We studied survival in relation to baseline levels and stability, the latter being understood as persistent levels in the initial group, or better, over 3 year period. Survival analysis was made by Kaplan-Meier estimation. Relative risk was calculated by Cox's proportional hazards model. RESULTS: During the 36 months of follow-up 53 patients died. AIDS progression risk or death was 4.8 times higher for the p24 antigen > = 40 pg/mL group than for the p24 antigen < 20 pg/mL one; patients with p24 antigen between 20-39 pg/mL relative risk was 2.5 times higher than those included in p24 antigen < 20 pg/mL group. These results emphasize that if we take into account the p24 antigen stability during these 36 months. In relation to progression study, 36 patients progressed. AIDS progression risk or death for p24 antigen > = 40 pg/mL group was 7.69 times higher in relation to that with p24 antigen levels between 20-39 pg/mL. The bivariable study shows that CD4 lymphocytes counts and p24 antigen level have quite an independent value. The comparison with viral load by PCR determination makes manifest discrepancy, difficult to explain. CONCLUSIONS: p24 antigen plasma level is a good survival and AIDS progress or death surrogate markers in HIV infected patients, and it is useful for 3 years or more. An isolated value < 20 pg/mL and, furthermore, the stability in successive controls under this concentration is a sign of good prognosis. Its value is emphasized with CD4+ lymphocytes count. It seem necessary that more comparative studies with viral load are required.