Efficient allocation of resources to prevent HIV infection among injection drug users: the Prevention Point Philadelphia (PPP) needle exchange program

Abstract

The objective of this study is to determine the allocation of resources within a multi-site needle exchange program (NEP) that achieves the largest possible reduction in new HIV infections at minimum cost. We present a model that relates the number of injection drug user (IDU) clients and the number of syringes exchanged per client to both the costs of the NEP and the expected reduction in HIV infections per unit time. We show that cost-effective allocation within a multi-site NEP requires that sites be located where the density of IDUs is highest, and that the number of syringes exchanged per client be equal across sites. We apply these optimal allocation rules to a specific multi-site needle exchange program, Prevention Point Philadelphia (PPP). This NEP, we find, needs to add 2 or 3 new sites in neighborhoods with the highest density of IDU AIDS cases, and to increase its total IDU client base by about 28%, from approximately 6400 to 8200 IDU clients. The case-study NEP also needs to increase its hours of operation at two existing sites, where the number of needles distributed per client is currently sub-optimal, by 50%. At the optimal allocation, the estimated cost per case of HIV averted would be dollar 2800 (range dollar 2300-dollar 4200). Such a favorable cost-effectiveness ratio derives primarily from PPP's low marginal costs per distributed needle.

Needle and syringe programs in Yunnan, China yield health and financial return

“…Our estimate of USD$138-198 in spending per infection averted is consistent with similar studies in other locations [16,37,38]. By adjusting the cost to account for the purchasing power parity for China (2007 PPP factor was 4.09 relative to 1 USD), the cost translates to $560-810 per infection averted, which is still very cost-effective in comparison to many developed countries ($3,000-$20,000 [39-42]).…”

The Cost-Effectiveness and Population Outcomes of Expanded HIV Screening and Antiretroviral Treatment in the United States

“…We estimated the average annual number of sexual partnerships (33–42), average condom use (33, 38–44), and the transmission probability per partnership (8, 45–55), for each sexual behavior mode, based on published data. The model captures HIV transmission via needle-sharing in a similar manner, as a function of the annual number of injections (56–58), average needle-sharing rates (41, 44, 57, 59), and the probability of transmission per shared needle (57, 60, 61). The probability of HIV transmission between two individuals depends on the infected individual’s gender, disease status, and treatment status, and the uninfected individual’s gender and circumcision status.…”

Potential population health outcomes and expenditures of HIV vaccination strategies in the United States

“…We also estimated behavioral parameters, including the annual number of same-sex and opposite-sex partners [61–70], condom use [56, 61–67, 71], annual number of drug injections [48, 58, 72], and needle-sharing rates [58, 61, 71, 73]. …”