AIDS incidence and survival in a hospital-based cohort of asymptomatic HIVseropositive patients in Sao Paulo, Brazil

Background In spite of the high incidence of AIDS in Brazil, few studies ha ve tried to evaluate the prognosis of asymptomatic HIV seropositive Brazili an patients. Methods A hospital outpatient facility-based cohort of HIV seropositive asy mptomatic subjects was followed to determine their probability of remaining AIDS-free at 2 and 4 years of follow-up, as well as the one-year estimated cumulative probability of survival far the AIDS incident cases. The cohort was made up of all asymptomatic HIV seropositive subjects referred to the Immunology Branch of a large university hospital in Sao Paulo, Brazil, betw een 1985 and June 1997. Results The cumulative probability of remaining free from AIDS was 79% (+/- 3.7% SE) at 2 years, and 64.4% (+/- 5.1% SE) at 4 years after first known positive anti-BTV serology. Women had a marginally significant better proba bility of remaining AIDS-free after both 2 and 4 years of known seropositiv ity, as compared with men. There were no significant differences in the pro gnosis of the infection by age; the only single parameter associated with b etter prognosis was an initial CD4+ count greater than or equal to 350/mu l . The probability of survival one year after the diagnosis of AIDS was 78%, and the 50% estimated probability of survival was 19 months. Older patient s (aged greater than or equal to 35 years) had a better prognosis, as sugge sted by their longer survival estimates (P = 0.06). Conclusions The probability of survival with AIDS observed in this study wa s higher than in the few previously published estimates for Brazil, However , since the time frame was so wide, it may not be entirely comparable with earlier studies. Some likely explanations for this possibly better prognosi s could include more efficient prophylaxis for opportunistic diseases, as w ell as an increase in the availability of anti-retroviral drugs. The 8% inc idence of AIDS at 2 years observed in this study for those individuals whos e initial CD4+ count was greater than or equal to 350/ml was close to that found in a large international epidemiological study of seroconverters.