Decreasing Impact of Requiring Assistance Injecting on HIV Incidence

To the Editors: The proportion of new HIV infections attributable to injection drug use is very high, with estimates of 30% globally outside of sub-Saharan Africa.1 Persons who inject drugs (PWID) continue to be at risk of HIV infection primarily through shared injecting equipment, and to a lesser extent unprotected sexual behavior.2,3 In our setting, in Vancouver, Canada, up to 40% of PWID have reported requiring assistance with injection of illicit drugs,4 a behavior that has been identified as a strong risk factor for syringe sharing5,6 and nearly doubles the risk of HIV infection compared with PWID who self-inject.4 To mitigate the well-established health risks associated with requiring assistance with injection, a number of harm reduction strategies have been implemented. Since opening in 2003, Insite, North America's first sanctioned medically supervised injection facility, has been associated with a large number of health and community benefits including significant reductions in syringe sharing.7,8 Insite staff provide clients with safer injection education, and, when necessary, provide verbal guidance and teaching to help users obtain venous access. Previous studies have demonstrated that many PWID who require assistance injecting benefit from instruction given at Insite.9,10 Federal guidelines governing the facility, however, require that all illicit drugs are self-administered and assisted injections are prohibited.11 As a result of this restriction, some PWID who are unable to inject on their own are compelled to seek assistance with injection in less hygienic environments. In response to this, a local drug user organization known as the Vancouver Area Network of Drug Users (VANDU) formed an Injection Support Team (IST) in 2005. The team, comprised of experienced PWID who have received extensive training in safer injecting education, provide outreach services to encourage safer injecting in the community. Guided by a detailed procedures' manual that the group developed, members of the team provide instruction on injecting technique to PWID.12 Because these interventions have been aimed at reducing vulnerability associated with requiring help injecting, this study was undertaken to see if requiring assistance injecting was associated with ongoing risk of HIV infection over time in this setting. METHODS The data for this study were derived from the Vancouver Injection Drug Users Study (VIDUS), an open prospective cohort of PWID in Vancouver, Canada, which has previously been described in detail.13,14 Briefly, PWID are eligible for VIDUS if they are older than or equal to 18 years of age, have injected illicit drugs in the previous month, and provide informed consent. At baseline and at semi-annual follow-up visits, participants complete an interviewer-administered questionnaire that elicits a range of data, including demographic characteristics, and information regarding drug use and HIV risk behaviors. Additionally, blood samples for HIV serology are drawn at baseline and at each follow-up visit for individuals whose test results were negative at the previous assessment. This study included individuals who were recruited between May 1996 and December 2013, who were HIV-negative at baseline, and had at least 1 follow-up visit. To investigate if there have been changes over time in the association between requiring assistance injecting and HIV incidence, the study period was a priori divided into 2 calendar-year intervals: 1996–2005 and 2006–2013. Requiring assistance injecting was determined by self-report as previously described and was treated as a time-updated variable.4 The primary end point of interest in this study was time to HIV seroconversion. The date of seroconversion was estimated using the midpoint between the last negative and the first positive antibody test results. Cumulative HIV incidence estimates were calculated for participants who required help injecting and those who did not require help using Kaplan–Meier methods. Survival curves were compared using the log-rank test. The association between requiring assistance injecting and time to HIV seroconversion was then examined using Cox proportional hazards modeling. RESULTS Between May 1996 and December 2013, 1665 individuals who were HIV-negative at baseline were recruited. In the 1996–2005 interval, 664 individuals (60.2%) reported requiring assistance injecting, which decreased to 433 (40.8%) in the 2006–2013 interval. There were 121 incident HIV cases during the 1996–2005 interval and 18 incident HIV cases during the 2006–2013 interval. As shown in Figure 1, among participants who required assistance injecting in the 1996–2005 interval, the cumulative HIV incidence at 24 months was 10.8% compared with 5.8% in participants who did not require assistance injecting (log-rank test, P = 0.003). Interestingly, during the 2006–2013 interval, the cumulative HIV incidence was the same between those who did and did not require help injecting (log-rank test, P = 0.886) (Fig. 1). In multivariate analyses, requiring assistance injecting was positively and significantly associated with HIV incidence during the 1996–2005 interval (hazard ratio = 2.19, 95% confidence interval: 1.50 to 3.20); however, this association was no longer statistically significant during the 2006–2013 calendar-year interval (hazard ratio = 1.13, 95% confidence interval: 0.33 to 3.87).FIGURE 1: Time to HIV infection among PWID in Vancouver stratified by requiring help injecting and period of follow-up (1996–2005 versus 2006–2013).DISCUSSION This study demonstrates that there have been significant reductions over time in both the incidence of requiring assistance with injection and HIV incidence. Furthermore, the strong association between requiring help injecting and HIV incidence that was observed in our setting early in the HIV epidemic4 is no longer present. These findings may be a result of increased harm reduction services implemented in the early and mid 2000s in our setting. As mentioned earlier, these services include having staff at Insite provide guidance and teaching to PWID to assist them in learning to self-inject, an intervention that has been previously shown to be effective.9,10 Among PWID not accessing Insite, education provided by VANDU's IST, as well as changes to needle exchange programs including improved operating hours and removing syringe distribution limits,15 may also have led to decreased syringe sharing among PWID who require assistance injection. This study is limited in that behavioral data were obtained through self-report, which may be subject to social desirable reporting.16 Additionally, the overall decline in HIV incidence in our setting is due to a range of factors, although Figure 1 implies that requiring help injecting is no longer a key risk factor. Future research should continue to evaluate the strength of the association between requiring assistance injecting and HIV incidence when compared with previously known risk factors associated with HIV incidence. Nevertheless, the results of this study support the existing literature demonstrating that local harm reduction strategies have resulted in positive changes in high-risk injecting behaviors.7,10 ACKNOWLEDGMENTS The authors thank the study participants for their contribution to the research, as well as current and past researchers and staff.

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