Declining seroprevalence in a very large HIV epidemic: Injecting drug users in New York City, 1991 to 1996

Objectives. This study assessed recent trends in HIV seroprevalence among injecting drug users in New York City. Methods. We analyzed temporal trends in HIV seroprevalence from 1991 through 1996 in 5 studies of injecting drug users recruited from a detoxification program, a methadone maintenance program, research store-fronts in the Lower East Side and Harlem areas, and a citywide network of sexually transmitted disease clinics. A total of 11 334 serum samples were tested. Results. From 1991 through 1996, HIV seroprevalence declined substantially among subjects in all 5 studies: from 53% to 36% in the detoxification program, from 45% to 29% in the methadone program, from 44% to 22% at the Lower East Side storefront, from 48% to 21% at the Harlem storefront, and from 30% to 21% in the sexually transmitted disease clinics (all P < .002 by x² tests for trend). Conclusions. The reductions in HIV seroprevalence seen among injecting drug users in New York City from 1991 through 1996 indicate a new phase in this large HIV epidemic. Potential explanatory factors include the loss of seropositive individuals through disability and death and lower rates of risk behavior leading to low HIV incidence.