## The Costs and Benefits of Insite: Executive Summary

The following statement is an executive summary of our recent study of the costs and benefits and cost-effectiveness of Vancouver’s Supervised Injection Site (SIS) (Andresen and Boyd, 2008). After a review of existing literature regarding both the efficacy of supervised injection sites generally, and Vancouver’s site more specifically, we engaged in two kinds of analysis to determine benefit to cost ratios for the Vancouver SIS, and cost effectiveness: linear trend analysis and mathematical modelling. We were particularly interested in Insite’s ability to impact HIV infections and overdose deaths, as we were able to obtain reliable temporal and spatial data for each of these two variables.

Linear trend analysis was hampered by the small number of observations that we could make post-Insite; the inability to demonstrate significant changes with a three year time line, post implementation, compromised the utility of trend analysis. Nonetheless, we did observe some positive changes post-Insite in rates of HIV infection within the three local health areas in Vancouver that are closest to Insite (a reduction in rates of HIV infection), and correspondingly negative changes in trends in the three local health areas of Vancouver most removed from Insite (an increase in rates of HIV infection). These changes in trends did not, however, reach the point of statistical significance, and we are left with the observation that little can be concluded from a linear trend analysis of overdose deaths or HIV infections. Additionally, we were required to assume that new cases of HIV amount to a proxy for new HIV infections, and to assume a regional stability in rates of HIV transmission and corresponding rates of detection. In these circumstances any results from our linear trend analysis should be interpreted cautiously.

Mathematical modelling was much more usefully employed, as we have reliable data regarding the number of injection drug users in the area, the number of injections annually, both inside Insite and outside, the extent of HIV transmission, the rate of HIV infection, the rate of overdose death in the area, the extent of behavioural change produced by Insite, and the number of overdoses within Insite. In every instance we used highly conservative estimates, and we employed four different mathematical models that have been widely cited in the literature.

We were able to identify a range of ratios of benefits to cost, based on the four different models. The data suggest that Insite produces an annual return on its investment that varies between approximately one and four times its cost, based on the model employed, and the assumptions resident within that model. We stress that these ratios are substantial under-estimates of the benefit to cost ratios of Insite, as many of the likely benefits could not be factored into our equations because of incomplete data: we had no systematic method for calculation of improved health among users, resulting from increased access to detox and other treatment services, and we could not separate Insite’s fixed costs from its variable costs. Further, a number of expenses that are only tangentially related to the annual operation of Insite – addiction services, counselling, immunizations, and diagnostic services – are included in the calculations of annual costs provided by Vancouver Coastal Health. It must be stressed that our conclusions are, accordingly, based upon both an under-estimate of the full range of benefits, and an over-estimate of the annual costs of operation of the facility.

Our data suggest that both increases in the current operating hours for Insite, and the building of additional facilities of a similar kind would yield benefits much in excess of costs required for such projects. We also note, given these data, that facilities providing opiates for addicts (and hence avoiding many of the criminal justice system costs that could not be contemplated here) should be given serious consideration, given both the apparent success of such initiatives in a number of European jurisdictions, and the value added nature of the cost savings in such schemes. Finally, we note that our cost analysis of the SIS demonstrates that its benefit to cost ratios are very similar to those provided by other kinds of treatment for drug addiction – that Vancouver’s SIS is properly thought of as one of many beneficial approaches for this complex problem.

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May 3rd, 2008 at 8:49 pm

[…] Neil has the Executive Summary of the study done to determine the cost/benefit analysis of Vancouver’s Supervised Injection Site (SIS), named Insite. Using four different mathematical models, their data suggests that Insite produces an annual return on its investment that varies between approximately one and four times its cost, based on the four models employed. They also stress that these ratios are substantial under-estimates of the benefit to cost ratios of Insite. […]

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