Our results demonstrate that 26% of HIV-positive IDUs frequently attended a local supervised injection facility. Consistent with the Risk Environment Framework (Rhodes, 2002
), in multivariate analysis, frequent SIF use was independently associated with both individual and contextual factors, including homelessness, daily heroin injection, and daily cocaine injection. The primary reasons given for not accessing the SIF included a preference for injecting at home and already having a safe place to inject. The health care services most commonly used at the SIF, aside from the supervised injecting room, included the needle exchange and nursing care.
Our findings indicate that the SIF has attracted a population of HIV-positive IDUs who are at heightened risk for adverse health outcomes, which is consistent with previous studies involving other IDU populations (Wood et al., 2006
). To our knowledge, though, this is the first study to specifically examine SIF use among HIV-positive IDUs. As in previous studies, IDUs in this study who used the SIF frequently were more likely to inject heroin and cocaine at least daily (Tyndall et al., 2006
). High-intensity cocaine use is explained by the brevity of cocaine’s half-life, which ranges between 40 and 60 minutes (McCoy, Lai, Metsch, Messiah, & Zhao, 2004
). As a result, cocaine users often inject 20–30 times per day and are at high risk to acquire or transmit infectious diseases, including HIV (Tyndall et al., 2003
). Therefore, it is encouraging that the SIF is attracting HIV-positive IDUs who frequently inject cocaine. The association between SIF use and daily heroin injection has also been reported in previous studies (Wood et al., 2006
). Given that heroin-related overdose accounts for a significant amount of preventable morbidity and mortality among IDUs (Darke & Hall, 2003
), it is encouraging that the SIF is attracting this subgroup and therefore likely reducing the risk of harm associated with opiate-related overdose (Kerr, Small, Moore, & Wood, 2007
; Milloy, Kerr, Tyndall, Montaner, & Wood, 2008
Our finding that homelessness was associated with more frequent SIF use has important implications. Homeless individuals are at heightened risk for various negative health outcomes (Culhane, Gollub, Kuhn, & Shpaner, 2001
; Galea & Vlahov, 2002
). As suggested by the Risk Environment Framework (Rhodes et al., 2006
), social conditions such as homelessness shape behavioral practices such as risky injecting. Homelessness has been strongly associated with public injecting, and HIV-positive IDUs who inject in public are vulnerable to bacterial infections arising from unsterile injecting (Young et al., 2004
). Indeed, because of compromised immunity, HIV-positive IDUs have a heightened susceptibility to bacterial infections that commonly result from frequent nonsterile injections (Lloyd-Smith et al., 2005
). These injection-related bacterial infections are associated with considerable morbidity and account for the majority of emergency room visits and hospitalizations among IDUs (Ebright & Pieper, 2002
; Palepu et al., 2001
). These issues and the present findings should be interpreted in the context of an earlier qualitative study that revealed that the Vancouver SIF has been effective in increasing access to assessment, care, and treatment of injection-related infections (Small, Wood, Lloyd-Smith, Tyndall, & Kerr, 2008
Although frequent SIF use was not independently associated with use of antiretroviral therapy (ARV), the bivariate association between SIF use and a reduced likelihood of being on ARV raises questions about the opportunities to provide enhanced HIV treatment via the SIF, especially in settings such as British Columbia, Canada, where ARV is provided free under the universal health care system. Previous studies have indicated that HIV-positive IDUs experience comparatively low rates of access and adherence to HIV treatment, and consequently this population has not benefited from modern HIV treatments to the same extent that other HIV-affected populations have (Kresina, Bruce, & McCance-Katz, 2009
; Wood et al., 2003
). Given that the SIF in Vancouver is attracting high-risk IDUs with a lower likelihood of receiving HIV treatment, the SIF could provide a venue for enhanced HIV care, including viral load and CD4 count testing, vaccinations and other preventive measures, and distribution of antiretroviral therapies. It has been suggested previously that the integration of existing harm reduction services, including SIFs, into treatment efforts that target IDUs could enhance HIV disease monitoring and treatment provision (Kerr, Kimber et al., 2007
), and it is noteworthy that another local SIF (the Dr. Peter Centre) limits its clientele to HIV-positive IDUs and provides many HIV-specific services (Krüsi, Small, Wood, & Kerr, 2009
The subanalyses of SIF use revealed several reasons why some HIV-positive IDUs refrain from using Insite. Already injecting in a safe place, preferring to inject at home, the distance from the site, preferring to inject in private, and requiring help injecting were frequently reported barriers to using the SIF. Consistent with the Risk Environment Framework (Rhodes et al., 2006
), efforts to remove structural barriers to prevention and treatment services are critical to ensuring the optimal impact of such services. Efforts aimed at increasing coverage of SIFs locally should therefore focus on both increasing the number of SIFs (and their geographic coverage) and modifying rules that prevent assisted injecting. Future research should seek to evaluate the impact of these types of structural changes to SIF program delivery.
We also found that HIV-positive participants in this study used various services at the SIF aside from the supervised injecting service. Given the high intensity of injecting among SIF users, it is encouraging that many IDUs were using the syringe exchange and drug and alcohol counseling services. As well, in light of the fact that many HIV-positive IDUs were using the SIF’s nursing services, the SIF could potentially expand the provision of HIV treatment and care by providing a range of HIV-specific services (e.g., disease monitoring, referral to HIV specialist physicians, and provision of daily dispensed antiretroviral therapy). In this particular setting, where health care is available to all free of charge, the barriers to treatment and care faced by many HIV-positive IDUs are other than financial ones. The SIF is therefore an ideal environment in which to offer HIV-specific services to IDUs, as it makes treatment and care more readily accessible to this population.
This study has several limitations. First, like most other cohort studies involving high-risk IDUs, ACCESS is not a random sample. Therefore, our study findings may not generalize well to the larger population of HIV-positive IDUs in Vancouver. Second, given the variations across settings, including differences in high-risk behaviors in other urban environments, our findings may not generalize well to HIV-positive IDUs in other locations. Third, we relied on a dichotomous outcome, and several of our independent variables were also dichotomized. Although the use of a continuous outcome may have allowed for a more nuanced analysis and less restricted variance across measures, we note that we were able to detect several significant associations between the outcome and independent variables that were considered. Last, we relied on self-reported measures, which may have introduced response biases into our results, such as socially desirable responding. Thus, we may have underestimated the sensitive behaviors and experiences, such as injection drug use and sex work involvement, among the participants.