AIDS incubation period in Spain before highly active antiretreviral therapy

BACKGROUND: TO evaluate the impact of new antiretroviral therapies on progr ession of HIV infection, is necessary to know what was the situation before their introduction. In Spain, no data on the incubation period of AIDS fro m all transmission categories have been available so far. SUBJECTS AND METHOD: Data from 6 well established seroconverter cohorts wit h well documented times of HIV seroconversion (presence of an HIV negative test) identified from 1982 to current date were analysed using Kaplan-Meier methods, allowing for late entry, Cox regression and log-normal regression , RESULTS: Of the 820 individuals analyzed, 80.34% were men, 57% intravenous drug users, 22% homosexual and 21% haemophilics. Median age at seroconversi on was 25 years; median seroconversion year was 1991 and median follow-up w as 4.11 years (range, 0-14.59). The incubation period of AIDS up to Decembe r 1996 was 10 years; only age at seroconversion relative risk [RR], 1.026; 95% CI, 1.005-1.047) and gender (RR, 0.58; 95% CI, 0.35-0.99) were associat ed with progression to AIDS with no effect of calendar year. CONCLUSIONS: Progression estimates to AIDS in Spain up to 1996 are similar to other European cohorts, so is the age effect, with no calendar year effe ct up to that date. This shows how therapeutic interventions measured in cl inical trials, which measure efficacy, do not necessarily translate in impr ovements at the population level, supporting the need to follow seroconvert er cohorts to evaluate impact of new antiretroviral therapies.