The role of needle exchange programs in HIV prevention

Injecting drug users (IDUs) are at high risk for infection by human immunod eficiency virus (HIV) and other blood-borne pathogens, In the United States , IDUs account for nearly one-third of the cases of acquired immunodeficien cy syndrome (AIDS), either directly or indirectly (heterosexual and perinat al cases of AIDS where the source of infection was an IDU). IDUs also accou nt for a substantial proportion of cases of hepatitis B (HBV) and hepatitis C (HCV) virus infections. The primary mode of transmission for HIV among I DUs is parenteral, through direct needle sharing or multiperson use of syri nges, Despite high levels of knowledge about risk, multiperson use of needl es and syringes is due primarily to fear of arrest and incarceration for vi olation of drug paraphernalia laws and ordinances that prohibit manufacture , sale; distribution, or possession of equipment and materials intended to be used with narcotics. It is estimated that in 1997 there were approximate ly 110 needle exchange programs (NEPs) in North America. In part, because o f the ban on the use of Federal funds for the operation of needle exchange, it has been difficult to evaluate the efficacy of these programs, This cha pter presents data from the studies that have evaluated the role of NEPs in HIV prevention, Evidence for the efficacy of NEPs comes from three sources: (I) studies ori ginally focused on the effectiveness of NEPs in non-HIV blood-borne infecti ons, (2) mathematical modeling of data on needle exchange on HIV seroincide nce, and (3) studies that examine the positive and negative impact of NEPs on HIV and AIDS. Case-control studies have provided powerful data on the positive effect of NEPs on reduction of two blood-borne viral infections (HBV and HCV) For exa mple, a case-control study in Tacoma, Washington, showed that a six-fold in crease in HBV and a seven-fold increase in HCV infections in IDUs were asso ciated with nonuse of the NEP. The first federally funded study of needle exchange was an evaluation of th e New Haven NEP, which is legally operated by the New Haven Health Departme nt. Rather than relying on self-report of reduced risky injection drug use, this study utilized mathematical and statistical modeling, using data from a syringe tracking and testing system. Incidence of HIV infection among ne edle exchange participants was estimated to have decreased by 33% as a resu lt of the NEP. A series of Government-commissioned reports have reviewed the data on posit ive and negative outcomes of NEPs. The major reports are from the National Commission on AIDS; the U.S. General Accounting Office; the Centers for Dis ease Control/University of California; and the National Academy of Sciences . The latter two reports are used in this chapter. The aggregated results support the positive benefit of NEPs and do not supp ort negative outcomes from NEPs. When legal restrictions on both purchase a nd possession of syringes are removed, IDUs will change their syringe-shari ng behaviors in ways that can reduce HIV transmission. NEPs do not result i n increased drug use among participants or the recruitment of first-time dr ug users.