Objective: To examine the effect of recent developments in antiretroviral therapy on HIV disease progression and survival.
Design: Retrospective cohort study.
Participants and setting: Two cohorts of people with HIV were defined retrospectively from the records of a large immunology laboratory. The first cohort were subjects whose CD4+ T cell counts had dropped to 200 x 10(6)/L during 1990, and the second were subjects whose CD4+ T cell counts had dropped to 200 x 10(6)/L in 1994.
Main outcome measures: HIV disease progression and survival was determined over a minimum three years of follow-up for each cohort (i.e., 1990-1993; 1994-1997).
Results: 346 subjects were included in the analysis (193 subjects from 1990 and 153 from 1994). The relative risk of progression to AIDS in the 1994 cohort compared with the 1990 cohort was 0.57 (95% confidence interval, 0.35-0.91; P = 0.018) and the relative risk of death was 0.20 (95% confidence interval, 0.08-0.49; P < 0.001).
Conclusions: There were 43% fewer AIDS cases and 80% fewer deaths in the time following the increased availability of combination antiretroviral therapy in Australia.