"Focusing on the base assumption of decreased needle sharing as the only effect of the supervised injection facility, we found that the facility was associated with an incremental net savings of almost $14 million and 920 life-years gained over 10 years. When we also considered the health effect of increased use of safe injection practices, the incremental net savings increased to more than $20 million and the number of life-years gained to 1070. Further increases were estimated when we considered all 3 health benefits: the incremental net savings was more than $18 million and the number of life-years gained 1175."
Bayoumi, Ahmed M. and Zaric, Gregory, "The cost-effectiveness of Vancouver’s supervised injection facility," Canadian Medical Association Journal (Ottawa, Ontario: November 18, 2008), Vol. 179, Issue 11, p. 1143.