Has the rate of progression to AIDS changed in recent years?

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Abstract
To investigate whether the rate of progression to AIDS has changed over time by testing an effect of the year of seroconversion on AIDS onset (Centers for Disease Control and Prevention 1987 revised classification), next to an effect of the calendar period of follow-up. French multicentre prospective study of 385 homosexual and heterosexual subjects and 231 subjects from a multicentre study of European injecting drug users (IDU), all with a documented date of HIV-1 seroconversion. The effect of the year of seroconversion was compared by the log-rank test. Crude and adjusted relative hazard (ARH) were quantified using the Cox model. Calendar period of follow-up was studied separately for sexual exposure group and IDU and treated as a time-dependent variable in a Cox model. In the 616 study subjects the year of seroconversion was not significantly related to AIDS occurrence (n = 108); the ARH was 0.88 [95% confidence interval (CI), 0.56–1.38] for those who seroconverted in 1988–1989, and 1.17 (95% CI, 0.61–2.25) for those who seroconverted after 1989, compared with those who seroconverted before 1988. In the sexual exposure group, a clear trend towards less rapid progression to AIDS was observed in subjects followed in 1991–1992 (ARH, 0.49; 95% CI, 0.24–0.99) and after 1992 (ARH, 0.54; 95% CI; 0.24–1.21), compared with those followed before 1991. This favorable trend was not observed in IDU despite a significant decrease over time of Pneumocystis carinii pneumonia as AIDS-defining illness. Conversely to sexual exposure groups, the frequency of antiretroviral treatment (mainly zidovudine) prescription was still low during the most recent calendar periods in IDU when the CD4 count threshold of 200 × 106/l was reached. No evidence was found of a change in the rate of progression to AIDS in subjects who seroconverted in recent years. Furthermore, conversely to sexual exposure groups, the lack of favorable trends in IDU users followed in recent years suggest that health-care systems are not always adapted to their lifestyles.