panded networks of high-risk users, more discarded needles in the community, and changes in crime trends. Modest evidence shows that NSE does not increase the number of discarded needles in the community, and that injection frequency does not increase among NSE participants. Weak evidence and limited data suggest that programs that include NSEs do not lead to new users, expanded drug networks, or increases in crime.
NSEs can serve as important links to health and social services for drug users who otherwise might not have access to treatment and care. Examples of such services include referrals to drug treatment, voluntary HIV counseling and testing, and medical care such as vaccinations and diagnosis of infections.
To assess the role of NSEs as a bridge to treatment, Strathdee et al. (1999) conducted a prospective cohort study in Baltimore. The study found that NSE attendance and health care use were each independently associated with entry into detoxification. HIV-seropositive NSE attenders were more than three times as likely to enter a detoxification program in the first year after the NSE began, but this result diminished over time. One explanation is that IDUs seeking treatment visited the NSE in large numbers when it first opened. A study at a New Haven NSE found that known syringe exchangers accounted for only 27 percent of requests for drug treatment (Heimer, 1998). Among the requesters, there was a strong association between heroin use and use of the NSE, and between alcohol use and non-users. This reveals that many people seeking drug treatment are not NSE clients, and that a treatment referral program could reach a larger target audience.
IDUs are likely to use services offered through an NSE beyond referrals for drug treatment. Porter et al. (2002) conducted a cross-sectional study at a needle and syringe exchange in Philadelphia offering four types of services: HIV voluntary counseling and testing, medical care, drug treatment referrals, and referrals to other services. The sample (n=43) included needle and syringe exchange users and non-users. Thirty-nine percent of the sample used at least one service besides needle exchange, with most of these participants using services that did not require outside follow-up. Twenty-eight percent had heard of at least one service beyond needle and syringe exchange, but had not used the additional service. Reasons for not using available services included access to these services through other means, and unwillingness to spend time waiting for them. The remaining study participants were either not aware that additional services existed or were aware that other services were available but had no knowledge of the