Declining AIDS mortality in Amsterdam: contributions of declining HIV incidence and effective therapy.

INTRODUCTION: We aimed to evaluate the impact of highly active antiretroviral therapy (HAART) on AIDS mortality, taking into account earlier HIV incidence patterns. METHODS: Using AIDS Surveillance data (1982-2000), we calculated the observed course of the AIDS epidemic among homosexual men in Amsterdam, The Netherlands. We used the HIV incidence patterns (1980-2000) among homosexual men participating in the hepatitis B vaccine trial and the Amsterdam Cohort Study and those attending the Amsterdam sexual transmitted infections clinic, together with the time from seroconversion to AIDS and death in the pre-HAART era, to estimate the natural course of the AIDS epidemic if HAART had not been introduced. RESULTS: The estimated course of the AIDS epidemic without the benefits of HAART showed a decline in AIDS mortality, but this estimated decline was not as strong as the observed decline. Taking into account the HIV incidence over calendar time, we estimated that 331 deaths among homosexual men were prevented by HAART between 1996 and 2000 in Amsterdam. CONCLUSION: The decline in AIDS mortality was the result of both HAART and a decline in the HIV incidence in the early 1980s. When evaluating the effect of HAART on mortality, changes in HIV incidence must also be considered.