Effectiveness of combined antiretroviral therapy on multiple aids-defining illnesses in an hiv seroconverter cohort

Introduction: Several observational studies support the protective effect of combined antiretroviral therapy (cART) on time to first AIDS-defining event, but the effect on multiple AIDS defining illnesses remains unclear. The aim of this study is to analyse whether the protective effect of cART persists beyond the first AIDS-defining illness. Material and methods: A total of 1938 subjects from GEMES seroconverter cohort have been included. To analyse cART effectiveness, calendar time has been divided into three periods according to antiretroviral availability. A population-averaged proportional hazard model with staggered entries that counted the gap time, and had event-specific baseline risks, was fitted. Results: During follow-up, 1524 (78.6%), 259 (13.4%), 83 (4.3%) and 72 (3.7%) subjects incurred 0, 1, 2, and 3 or more AIDS-defining illnesses, respectively. After adjustment for sex, age at seroconversion and exposure category, the Relative Risk (RR) of AIDS in the cART period was 0.38 (95%CI 0.30-0.48) compared with the 1992-95 period. The RR of the first, second and third AIDS-defining illness in the cART period were 0.40 (95% CI: 0.32-0.50), 0.27 (95% CI: 0.15-0.50) and 0.41 (95% CI: 0.18-0.96) respectively, relative to the reference calendar period when we allowed the odds ratios to vary by the number of prior AIDS-defining events. The relative risk of AIDS, taking all events into account, was 0.32 (95% CI: 0.25-0.40). Intravenous drug users have a higher risk of developing a first episode of AIDS than homosexuals, RR: 2.14 (95% CI: 1.48-3.10). Conclusions: Results indicate that the relative effect of cART appears to be both protective and stable over multiple AIDS-defining illnesses. Analysis of multiple AIDS-defining illnesses improves the precision of the estimated relative risk. (C) 2010 Elsevier Espana, S.L. All rights reserved.