[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.