Trends in HIV infection among intravenous drug users in Innsbruck, Austria.

The first HIV test among intravenous drug users (IVDUs) at the AIDS clinic and/or the drug dependency clinic of the University of Innsbruck was the basis for the calculation of the proportions of those testing HIV seropositive annually over the period 1985-1990. The numbers testing HIV seropositive at the drug dependency clinic declined drastically, from 72.2% in 1985 to 12.5% in 1990 (chi 2 = 29.62, p less than 0.0001), whereas they rose at the AIDS clinic during this period, from 48.4% to 100% (chi 2 = 5.82, p = 0.016). Overall 132 of the 268 (49.2%) individuals examined tested HIV seropositive. There were 102 individuals of the original 146 seronegative IVDUs who were retested, for an overall incidence rate of HIV seroconversion of 5.8/100 persons-years. Risk of seroconversion was associated with a steady sexual partnership with an HIV seropositive IVDU and with an age of less than or equal to 25 years at study entry (13.1 versus 8.7/100 persons-years). No seroconversions occurred in the subgroup of patients treated by the methadone maintenance treatment program. The cumulative incidence (Kaplan-Meier) rate for HIV seropositivity after 64 months was 22%, lower than the proportions testing HIV seropositive found in 1985 at each of the two clinics, which suggests that the speed of the spread of the epidemic of HIV infection among IVDUs has slowed in our region. Counseling of IVDUs should emphasize the risks of sexual acquisition, particularly among persons with steady relationships who may not perceive their risk.