HIV incidence among injection drug users in New York City, 1992-1997: Evidence for a declining epidemic

Objectives. We assessed recent (1992-1997) HIV incidence in the large HIV epidemic among injection drug users in New York City. Methods. Data were compiled from 10 separate studies (N = 4979), including 6 cohort studies, 2 'repeat service user' studies, and 2 analyses of voluntary HIV testing and counseling services within drug treatment programs. Results. In the 10 studies, 52 seroconversions were found in 6344 person-year at risk. The observed incidence rates among the 10 studies were all within a narrow range, from 0 per 100 person-years at risk to 2.96 per 100 person-years at risk. In 9 of the 10 studies, the observed incidence rate was less than 2 per 100 person-years at risk. The weighted average incidence rate was 0.7 per 100 person-years at risk. Conclusions. The recent incidence rate in New York City is quite low for a high-seroprevalence population of injection drug users. The very large HIV epidemic among injection drugs users in New York City appears to have entered a 'declining phase,' characterized by low incidence and declining prevalence. The data suggest that very large high- seroprevalence HIV epidemics may be 'reversed'.