Needle exchange and the HIV epidemic in Vancouver: lessons learned from 15 years of research

Abstract

During the mid-1990s, Vancouver experienced a well characterized HIV outbreak among injection drug users (IDU) and many questioned how this could occur in the presence of a high volume needle exchange program (NEP). Specific concerns were fuelled by early research demonstrating that frequent needle exchange program attendees were more likely to be HIV positive than those who attended the NEP less frequently. Since then, some have misinterpreted this finding as evidence that NEPs are ineffective or potentially harmful. In light of continuing questions about the Vancouver HIV epidemic, we review 15 years of peer-reviewed research on Vancouver's NEP to describe what has been learned through this work. Our review demonstrates that: (1) NEP attendance is not causally associated with HIV infection, (2) frequent attendees of Vancouver's NEP have higher risk profiles which explain their increased risk of HIV seroconversion, and (3) a number of policy concerns, as well as the high prevalence of cocaine injecting contributed to the failure of the NEP to prevent the outbreak. Additionally, we highlight several improvements to Vancouver's NEP that contributed to declines in syringe sharing and HIV incidence. Vancouver's experience provides a number of important lessons regarding NEP. Keys to success include refocusing the NEP away from an emphasis on public order objectives by separating distribution and collection functions, removing syringe distribution limits and decentralizing and diversifying NEP services. Additionally, our review highlights the importance of context when implementing NEPs, as well as ongoing evaluation to identify factors that constrain or improve access to sterile syringes.

Figure 1

Figure 1 (a+b). Frequencies of responses to the question regarding why participants had difficulty accessing sterile needles among the 69 participants who acquired most of their needles from the fixed site exchange (1a) or from the vans (1b). Reprinted from Wood et al. (2002b).

Figure 2

the VANDU needle exchange table at the corner of Main and Hastings Streets. Reprinted from Kerr et al. 2006.

Figure 3

Average number of sterile syringes providing during each 4-week period to and after operation 24/7. Reprinted from Wood et al. (2003c).

Figure 4

The Kaplan-Meier cumulative HIV incidence rate among injection drug users stratified by daily NEP use and restricted to those that did and did not report daily cocaine injection at baseline. Reprinted from Wood et al. 2007.

Figure 5

Hazard ratios and 95% CI for HIV infection associated with daily NEP use after the stepwise inclusion of potential confounders. Reprinted from Wood et al. (2007).

Figure 6

Proportion of VIDUS participants reporting (a) syringe borrowing and (b) syringe lending: Vancouver, British Columbia, 1998–2003. Reprinted from Kerr et al. 2010.