Changing incidence of AIDS-defining illnesses in the era of antiretroviral combination therapy

Objective: To determine the incidence of AIDS-defining opportunistic infections and malignancies over a 5-year period from 1992 to 1996.

Study population: Subcohort of 1003 homosexual men with HIV infection and CD4 count less than 200 × 10⁶cells/l from the Frankfurt AIDS Cohort Study.

Methods: Data including the earliest date that a CD4 T-lymphocyte count < 200 × 10⁶/l was reached and the dates of AIDS-defining events were compiled from medical records. Incidence analyses for AIDS-defining events and death during the subsequent 5 years (1992-1996) were performed using rates per 100 person-years of exposure.

Results: During the observation period, the number of patients per year with CD4 T-lymphocyte counts < 200 × 10⁶/l varied between 402 and 511. In 1992, 56.7% of patients experienced at least one AIDS-defining illness, and 20.7% in 1996. The annual number of AIDS-defining events per 100 patient-years of observation declined from 143.5 in 1992 to 38.3 in 1996, and the number of AIDS-related deaths fell from 25.7 to 12.9. Analysis of the number of events confirmed this trend for malignancies and single opportunistic infections, with the exception of mycobacterial diseases.

Conclusions: The incidence of AIDS-defining events in patients with advanced HIV infection at Frankfurt University Hospital has declined by more than 70% from 1992 to 1996.