How many HIV infections are prevented by Vancouver Canada's supervised injection facility?

Center for AIDS Intervention Research, Department of Psychiatry and Behavioral Medicine, Medical College of Wisconsin, Milwaukee, 53202, United States.
The International journal on drug policy (Impact Factor: 3.19). 03/2011; 22(3):179-83. DOI: 10.1016/j.drugpo.2011.03.003
Source: PubMed


Mathematical modelling analyses of drug injection-related HIV risk reduction interventions can provide policy makers, researchers, and others with important information that would be difficult to obtain through other means. The validity of the results of mathematical modelling analyses that rely on secondary data sources critically depends on the model(s) employed in the analyses and the parameter values used to populate the models. A recent article in the International Journal of Drug Policy by Andresen and Boyd (2010: 70-76) utilised four different mathematical models of injection-related HIV transmission to estimate the number of HIV infections prevented by Vancouver Canada's Insite supervised injection facility (SIF). The present article reviews and critiques the mathematical models utilised in the Andresen and Boyd article, then describes an alternative-and potentially more accurate-method for estimating the impact of the Insite SIF. This model indicates that the SIF prevents approximately 5-6 infections per year, with a plausible range of 4-8 prevented infections. These estimates are far smaller than suggested by Andresen and Boyd (19-57 prevented infections).

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    • "This lower cost assumption is based on the recognition that PWID may experience societal limitations or certain self-imposed barriers making it less likely for PWID to take full advantage of the medical system. This value is based on the most recent research in this area (Andresen & Jozaghi, 2012;Jozaghi et al., , 2014Pinkerton, 2010Pinkerton, , 2011). The medical cost of new HCV infections According to the World Health Organization, HCV infection is a leading risk for liver disease, affecting more than 170 million people worldwide (World Health Organization, 1998); and since the 1980s, PWID have been found at a greater risk for contracting the virus (Hagan, 1998;Roy et al., 2002). "

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    • "Similarly, the 2011 study revealed that a mere 4 to 8 new HIV cases are averted each year [17]. With greatly reduced benefit-cost ratios of 0.37 [16] and 0.8 [17], respectively, these results suggest that the SIF portion of Insite is not a practical harm reduction option, at least in economic terms. "
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    ABSTRACT: Background Supervised injection facilities (SIFs) are venues where people who inject drugs (PWID) have access to a clean and medically supervised environment in which they can safely inject their own illicit drugs. There is currently only one legal SIF in North America: Insite in Vancouver, British Columbia, Canada. The responses and feedback generated by the evaluations of Insite in Vancouver have been overwhelmingly positive. This study assesses whether the above mentioned facility in the Downtown Eastside of Vancouver needs to be expanded to other locations, more specifically that of Canada’s capital city, Ottawa. Methods The current study is aimed at contributing to the existing literature on health policy by conducting cost-benefit and cost-effective analyses for the opening of SIFs in Ottawa, Ontario. In particular, the costs of operating numerous SIFs in Ottawa was compared to the savings incurred; this was done after accounting for the prevention of new HIV and Hepatitis C (HCV) infections. To ensure accuracy, two distinct mathematical models and a sensitivity analysis were employed. Results The sensitivity analyses conducted with the models reveals the potential for SIFs in Ottawa to be a fiscally responsible harm reduction strategy for the prevention of HCV cases – when considered independently. With a baseline sharing rate of 19%, the cumulative annual cost model supported the establishment of two SIFs and the marginal annual cost model supported the establishment of a single SIF. More often, the prevention of HIV or HCV alone were not sufficient to justify the establishment cost-effectiveness; rather, only when both HIV and HCV are considered does sufficient economic support became apparent. Conclusions Funded supervised injection facilities in Ottawa appear to be an efficient and effective use of financial resources in the public health domain.
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    • "Incidence rate estimates assume 65.4 injections with borrowed syringes per year per PWID (Pinkerton, 2011) and a 0.0066 perinjection probability of HIV transmission (Kaplan & O'Keefe, 1993). "
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    ABSTRACT: The study was undertaken to assess the potential effectiveness of combined HIV prevention on the very high seroprevalence epidemic among persons who inject drugs (PWID) in Tallinn, Estonia, a transitional country. Data from community-based cross-sectional (respondent-driven sampling) surveys of PWID in 2005, 2007, 2009, and 2011 were used together with mathematical modeling of injection-associated HIV acquisition to estimate changes in injection-related HIV incidence during these periods. Utilization of one, two, or three of the interventions available in the community (needle and syringes exchange program, antiretroviral treatment [ART], HIV testing, opioid substitution treatment) was reported by 42.5%, 30.5%, and 11.5% of HIV+ and 34.7%, 36.4%, and 5.7% of HIV- PWIDs, respectively, in 2011. The modeling results suggest that the combination of needle/syringe programs and provision of ART to PWID in Tallinn substantially reduced the incidence of HIV infection in this population, from an estimated 20.7/100 person-years in 2005 to 7.5/100 person-years in 2011. In conclusion, combined prevention targeting HIV acquisition and transmission-related risks among PWID in Tallinn has paralleled the downturn of the HIV epidemic in this population.
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