Costs of HIV prevention among out-of-treatment drug-using women: results of a randomized controlled trial.

Human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) impose a significant health and economic burden to society, yet HIV-prevention programs, which avert hundreds of thousands of HIV infections and save money, are significantly underfunded in the United States1 and abroad.In many settings, both national and global, resources to combat HIV and AIDS are severely constrained, further bolstering the need for economic analyses to identify the most efficient use of resources. Accurate estimates of the costs of HIV prevention are critical both to place a precise value on such programs as well as to inform efforts to scale up financing to more closely meet public health needs. Cost analyses may also serve an important role in strengthening the political will for greater programmatic investment. Economic theory offers the theoretical foundation for valuing costs in assessing medical and public health interventions. In a perfectly free market economy, for example, without market failures or distortions, the price of resources can be used as real resource costs—the opportunity costs—of a given intervention or program. Medical and public health programs, however, rarely operate under ideal market conditions; therefore, prices cannot always be used to value resources, and costs must be empirically estimated. While there are two general approaches, micro-costing and gross-costing, for estimating costs that are theoretically grounded in economic principles, micro-costing is preferred for cost estimation for programs in public health and medicine. The Panel on Cost-Effectiveness in Health and Medicine (a nonfederal panel of experts on cost-effectiveness analysis that was convened by the U.S. Public Health Service in 1993) has endorsed this approach.2 Micro-costing, which allows for the separation of different activities and cost categories, gathers detailed information, directly enumerating and valuing specific resources used in an intervention. Micro-costing measures exact amounts of resources to provide an accurate cost estimate; however, it is labor and resource intensive and, therefore, has had limited use. Although cost studies in HIV prevention exist,3–5 to our knowledge, micro-costing studies of HIV-prevention programs are inade-quate,6,7 if not entirely absent. This article presents the first full micro-costing study of HIV prevention among drug-using women. It also aims to address gaps in research by offering a standardized and uniform methodology of cost estimation. We developed a systematic methodology for measuring costs grounded in the theory and process of identifying, estimating, and valuing resource costs, and conducted a micro-costing study alongside a randomized controlled trial (RCT). We estimated and compared the costs of each of the three RCT arms of this study, which we called Women Teaching Women (WTW): (1) a modified National Institute on Drug Abuse (NIDA) Cooperative Agreement Standard Intervention (SI); (2) the SI and a field-based well woman exam (SI+WWE); and (3) the SI, WWE, and four educational sessions (SI+WWE+4ES) among female out-of-treatment crack-cocaine users and injecting drug users in St. Louis, Missouri. The specific aim of the WTW study was to reduce substance use and high-risk sexual behaviors among drug-using women through a holistic, peer-delivered intervention.8 We estimated total, variable, and fixed costs for the SI and additional costs for the two enhanced interventions (WWE and 4ES). We then compared the breakdown of cost categories across these intervention components. We estimated costs from both the service-provider and societal perspectives. We concluded with a sensitivity analysis of the robustness of these estimates to changes in key cost components.