Methods: We developed a Markov model of HIV-related costs, quality of life, and survival. Disease progression was determined by immunologic and virologic parameters. The likelihood of sexual transmission was based on viral load, knowledge of HIV status, and efficacy of counseling (base-case value = 20% reduction in transmission). With traditional counseling, the per-patient cost of pre-test counseling was $35 and of post-test counseling was $35 or $10 for patients with positive and negative results, respectively. We modeled the effects of streamlined counseling as reduced costs for pre-test counseling and how changes in risk behavior affected cost effectiveness.
Results: Given a 1% prevalence of unidentified HIV infection, a one-time HIV screening program with traditional counseling cost $14,083 per quality-adjusted life year (QALY) compared to no screening, and recurrent screening every 5-years cost $46,346/QALY compared with one-time screening. A program of streamlined counseling, with counseling costs of $5 (pre-test) and $35 and $2 (post-test for positives and negatives, respectively) cost $11,496/QALY for one-time screening relative to no screening and $17,101/QALY for recurrent screening relative to one-time screening. If streamlined counseling was associated with no reduction in risk behavior, the corresponding ratios were $23,130/QALY and $30,377/QALY. Because routine screening in low-risk populations is also being considered, we examined the cost-effectiveness of streamlined counseling when the prevalence of undiagnosed HIV was 0.1%. With traditional counseling, one-time HIV screening cost $42,671/QALY compared with no screening. Streamlined counseling makes one-time HIV screening in this population more economically favorable at $17,109/QALY versus no screening, but the cost effectiveness is modestly less favorable ($30,629/QALY gained) if streamlined counseling does not result in a reduction in risk behavior.
Conclusion: Streamlined counseling will considerably enhance the cost-effectiveness of routine HIV screening, particularly in low risk populations. Screening with streamlined counseling remains cost effective in low prevalence populations even if risk behavior is not reduced because transmission from continued risk behavior is in part offset by decreased transmission and increased QALYs associated with antiretroviral therapy.