Cost-effectiveness of HIV counseling and testing in US prisons.

The prevalence of human immunodeficiency virus (HIV) in correctional facilities is much higher than in the general population. However, HIV prevention resources are limited, making it important to evaluate different prevention programs in prison settings. Our study presents the cost-effectiveness of offering HIV counseling and testing (CT) to soon-to-be-released inmates in US prisons. A decision model was used to estimate the costs and benefits (averted HIV cases) of HIV testing and counseling compared to no CT from a societal perspective. Model parameters were HIV prevalence among otherwise untested inmates (1%); acceptance of CT (50%); risk for HIV transmission from infected individuals (7%); risk of HIV acquisition for uninfected individuals (0.3%); and reduction of risk after counseling for those infected (25%) and uninfected (20%). Marginal costs of testing and counseling per person were used (no fixed costs). If infected, the cost was $78.17; if uninfected, it was $24.63. A lifetime treatment cost of $186,900 was used to estimate the benefits of prevented HIV infections. Sensitivity and threshold analysis were done to test the robustness of these parameters. Our baseline model shows that, compared to no CT, offering CT to 10,000 inmates detects 50 new or previously undiagnosed infections and averts 4 future cases of HIV at a cost of $125,000 to prison systems. However, this will save society over $550,000. Increase in HIV prevalence, risk of transmission, or effectiveness of counseling increased societal savings. As prevalence increases, focusing on HIV-infected inmates prevents additional future infections; however, when HIV prevalence is less than 5%, testing and counseling of both infected and uninfected inmates are important for HIV prevention.