摘要：Objectives. We assessed the effects of syringe exchange program (SEP) policy on rates of HIV risk behavior and HIV incidence among injection drug users. Methods. Using a multivariate generalized estimating equation and Cox regression methods, we examined syringe borrowing, syringe lending, and HIV incidence among a prospective cohort of 1228 injection drug users in Vancouver, British Columbia. Results. We observed substantial declines in rates of syringe borrowing (from 20.1% in 1998 to 9.2% in 2003) and syringe lending (from 19.1% in 1998 to 6.8% in 2003) following SEP policy change. These declines coincided with a statistically significant increase in the proportion of participants accessing sterile syringes from nontraditional SEP sources ( P < .001). In multivariate analyses, the period following the change in SEP policy was independently associated with a greater than 40% reduction in syringe borrowing (adjusted odds ratio [AOR] = 0.57; 95% confidence interval [CI] = 0.49, 0.65) and lending (AOR = 0.52; 95% CI = 0.45, 0.60), as well as declining HIV incidence (adjusted hazard ratio = 0.13; 95% CI = 0.06, 0.31). Conclusions. Widespread syringe distribution appears to be a more effective SEP policy than do more restrictive SEP policies that limit syringe access. Efforts should be made to ensure that SEP policies and program design serve to maximize rather than hinder syringe access. Cities throughout the world are increasingly experiencing HIV epidemics among injection drug users (IDU) as a result of sharing contaminated injecting equipment. 1 In response, various initiatives such as syringe exchange programs (SEPs) have been established. 2 Despite the growing implementation of SEPs, IDU-driven HIV epidemics have persisted in some settings. 3 This has been true of Vancouver, British Columbia, Canada, which experienced one of North America's highest HIV rates although the city has been home to one of the continent's largest SEPs. 4 Preliminary reports have suggested that many local IDU have historically experienced difficulty accessing sterile syringes as a result of policy and programmatic factors such as limited hours of SEP operation and a rigid one-for-one syringe exchange policy (i.e., only 1 sterile syringe is distributed for every used syringe returned). 5 , 6 Indeed, studies from other settings have revealed the negative effects of restrictive SEP policies that limit access to sufficient numbers of sterile syringes, such as one-for-one exchange policies. 7 – 10 In an effort to maximize sterile syringe access and reduce rates of syringe sharing, between 2000 and 2002 the health authority in Vancouver modified its SEP policies by shifting from a focus on syringe exchange to a focus on syringe distribution. 11 This change in policy involved decentralizing SEP services by increasing the number of sites distributing syringes, diversifying the methods used to distribute syringes (including hotel-based SEPs and foot patrols), and removing the limit on the number of syringes that could be obtained. Also, the health authority in Vancouver required local health clinics to provide sterile syringes to local IDU and asked programs, such as Vancouver's street nurse program, that were already providing outreach and care to IDU to include syringe distribution in their activities. Further, IDU were able to acquire sterile syringes without having used syringes to exchange, and syringe distribution and collection programs were separated. At the same time, a local drug user organization, recognizing the problem with access to syringes, opened a peer-run SEP in the city's central drug-using area. 12 This program included both a fixed SEP and an outreach-based SEP service. The peer-run fixed SEP was later found to be reaching a subpopulation of IDU at heightened risk for HIV infection. 13 Although it has been suggested that SEPs are most effective when the focus of service is on distribution rather than exchange, 11 there is a dearth of evidence documenting the effect of such a focus on rates of syringe sharing and HIV incidence. Therefore, we sought to determine if the change in SEP policy was associated with changes in rates of used syringe sharing and HIV incidence among IDU.
