Cost-effectiveness of prevention referrals for high-risk HIV-negatives in San Francisco

We retrospectively assessed the cost-effectiveness of providing prevention referrals to high-risk seronegatives at HIV test sites in San Francisco. We examined the costs and effects from the perspectives of society and the San Francisco Department of Public Health (SFDPH). Cost categories assessed included referral materials, counsellor training and time required to make referrals, prevention services and the value of client time. Effect data are drawn from a study of 289 high-risk seronegatives and the published literature, and are applied to a city-wide caseload of 6,626 high-risk seronegatives. We estimate that a city-wide programme in San Francisco averts two HIV infections per year and yields net savings to society of $43,765, with a cost to the SFDPH of $20,738 per HIV infection averted. We conclude that providing HIV prevention referrals to high-risk seronegatives receiving antibody testing imposes significant costs, but has attractive cost-effectiveness when applied to a large high-risk population.