Decreased Odds of Injection Risk Behavior Associated With Direct Versus Indirect Use of Syringe Exchange: Evidence From Two California Cities

ABSTRACT

Background: While there is substantial evidence that syringe exchange programs (SEPs) are effective in preventing HIV among people who inject drugs (PWID), nearly all the evidence comes from PWID who obtain syringes from an SEP directly. Much less is known about the benefits of secondary exchange to PWID who get syringes indirectly from friends or acquaintances who visit an SEP for them. Objectives: We evaluated the effectiveness of direct versus indirect syringe exchange in reducing HIV-related high-risk injecting behavior among PWID in two separate studies conducted in Sacramento and San Jose, California, cities with quite different syringe exchange models. Methods: In both studies associations between direct and indirect syringe exchange and self-reported risk behavior were examined with multivariable logistic regression models. Study 1 assessed effects of a “satellite” home-delivery syringe exchange in Sacramento, while Study 2 evaluated a conventional fixed-site exchange in San Jose. Results: Multivariable analyses revealed 95% and 69% reductions, respectively, in high-risk injection associated with direct use of the SEPs in Sacramento and San Jose, and a 46% reduction associated with indirect use of the SEP in Sacramento. Conclusions/Importance: The very large effect of direct SEP use in Sacramento was likely due in part to home delivery of sterile syringes. While more modest effects were associated with indirect use, such use nevertheless is valuable in reducing the risk of HIV transmission of PWID who are unable or unwilling to visit a syringe exchange.

KEYWORDS:

• Secondary syringe exchange
• satellite syringe exchange
• HIV risk behavior
• people who inject drugs
• syringe exchange

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Funding

This work was supported by the National Institute of Mental Health [Grant number MH-42459] and the National Institute on Drug Abuse [Grant number DA-09529].

Acknowledgements

The authors thank Joseph Guydish, Meghan Morris, Judy Hahn, Bruce Schackman and two anonymous reviewers for their very helpful comments on drafts of the manuscript and Lynell Clancy for her insights into the operation of the Sacramento Area Needle Exchange. This paper is dedicated to the memory of Jim Britton, a hero of Sacramento syringe exchange, 1995–2007.

Notes

1 To arrange “home delivery” clients paged the on-duty exchanger to schedule the exchange of syringes at a specified location, often the client's home.

2 As stated, Study 1 participants were involved in a two-city evaluation of a community-level HIV-prevention intervention that was implemented in Sacramento (the comparison site, San Diego, received no intervention). The two Sacramento project staff who conducted interviews at the Sacramento site were not involved in any aspect of the community intervention but both volunteered as syringe exchangers and in that role each would have had contact with some of the 46 Study 1 respondents who reported direct use of the exchange. While we cannot ascertain which interviewer exchanged with which respondent, it is likely that half of the 46, or 23, were interviewed by someone they exchanged with. This is a potential problem since these respondents would have been less likely to acknowledge high-risk behavior. Two features of this study, however, mitigate this problem. First, the questionnaire items asking about high-risk behavior were immediately preceded by instructions that gave respondents “permission” to acknowledge high-risk behavior. Second, in multivariable analysis we adjusted for socially desirable response tendency. See the Variables section for further discussion of these procedures and their advantages.

3 It may be objected that respondents who were in committed relationships with a primary sexual partner might be mistaken about the “exclusiveness” of their relationship, the HIV status of the partner, or the willingness of the partner to share injection equipment with another PWID. Only 45 of 283 (or 16%) respondents in Study 1 and 15 of 169 (or 9%) fell into the category of only borrowing syringes from an HIV-negative regular sexual partner. However, while the exclusiveness of the partnership or borrowing syringes from another drug user following a negative HIV test may be questioned, a recent review (Nasarruddin et al., 2016) showed 85% to 94% disclosure of HIV status between PWID and intimate sexual partners. Disclosure was less likely for regular sexual partners who were also PWID although the review found that HIV-positive PWID who did not disclose tended to practice safer injection behavior to protect their partners. Please note that while the nine-item composite measure of injection risk was the focus of our multivariate analysis, we also analyzed our data using an alternative outcome (borrowing of unbleached syringes) that did not take an intimate partner's HIV status into account. Tables 1 and 3 show the proportion of direct, indirect and nonusers of the syringe exchange in Studies 1 and 2 who reported this practice. The results are fully consistent with our multivariate findings, with direct users being at lowest risk, nonusers at highest risk, and indirect users at intermediate risk.