| Table 4: Impact of needle exchange program over 5 years on cost savings if HIV incidence rate is higher without a needle exchange program (alternative 1) or number of injection drug users (IDUs) using the program increased (alternative 2) | ||||||
| Assumptions | Impact | |||||
| Case | No. of IDUs using program |
Baseline HIV prevalence, % |
HIV incidence with program, % |
HIV incidence without program, % |
No. of HIV cases prevented |
Cost savings to cost ratio |
| Baseline | 275* | 3‡ | 2§ | 4# | 24 | 4:1 |
| Alternative 1 | 275 | 3 | 2 | 11¶ | 92 | 17:1 |
| Alternative 2 | 550† | 3 | 2 | 4 | 47 | 8:1 |
| *Estimated by program staff. | ||||||
| †Derived from DeVillaer et al.31 | ||||||
| ‡Derived from Elnitsky et al.16 | ||||||
| §Derived from Kaplan.34 | ||||||
| #Derived from Nelson et al.20 | ||||||
| ¶Derived from Metzger et al.21 | ||||||