Cost-threshold analyses of the National AIDS Demonstration Research HIV prevention interventions.

OBJECTIVE: The goal of the multisite National AIDS Demonstration Research (NADR) program was to reduce the sexual and drug injection-related HIV risks of out-of-treatment injection drug users and their sex partners. Previous analyses have established that the NADR interventions were effective at changing participants' risky behaviors. This study was to determine whether the NADR program also was cost-effective. METHODS: Data from eight NADR study sites were included in the analysis. A mathematical model was used to translate reported sexual and injection-related behavior changes into an estimate of the number of infections prevented by the NADR interventions and then to calculate the corresponding savings in averted HIV/AIDS medical care costs and quality-adjusted years of life, assuming United States values for these parameters. Because cost data were not collected in the original NADR evaluation, the savings in averted medical care costs were compared with the cost of implementing a similar intervention program for injection drug users. RESULTS: The eight NADR interventions prevented approximately 129 infections among 6629 participants and their partners. Overall, the NADR program would be cost saving (i.e. provide net economic savings) if it cost less than US$2107 per person and would be cost-effective if it cost less than US$10,264 per person. Both of these estimates are considerably larger than the US$273 per person cost of the comparison intervention. There was substantial cross-site variability. CONCLUSIONS: The results of this analysis strongly suggest that the NADR interventions were cost-saving overall and were, at the very least, cost-effective at all eight sites. In the United States and other developed counties, investments in HIV-prevention interventions such as these have the potential to save substantial economic resources by averting HIV-related medical care expenses among injection drug users.

Outreach-based HIV prevention for injecting drug users: a review of published outcome data.

OBJECTIVE: Over the past decade, a body of observational research has accrued about the effects of outreach-based human immunodeficiency virus (HIV) interventions for drug users. The authors reviewed the findings related to postintervention behavior changes and integrated findings across studies to provide the best estimate of program impact. METHODS: The authors conducted a computerized literature search to locate published accounts of HIV intervention effects on drug users. Thirty-six publications covered outreach-based HIV risk reduction interventions for out-of-treatment injecting drug users (IDUs) and reported intervention effects on HIV-related behaviors or HIV seroincidence. Two-thirds of the publications reported that participation in street-based outreach interventions was followed with office-based HIV testing and counseling. The authors described the theoretical underpinnings of outreach intervention components, the content of the interventions, and the outcome measures that investigators used most frequently. The authors also described and critiqued the evaluation study designs that were in place. Because most of the evaluations were based on pretest and posttest measures of behavior rather than on controlled studies, results were examined with respect to accepted criteria for attributing intervention causality, that is, the plausibility of cause and effect, correct temporal sequence, consistency of findings across reports, strength of associations observed, specifically of associations, and dose-response relationships between interventions and observed outcomes. RESULTS: The majority of the published evaluations showed that IDUs in a variety of places and time periods changed their baseline drug-related and sex-related risk behaviors following their participation in a outreach-based HIV risk reduction intervention. More specifically, the publications indicated that IDUs regularly reported significant follow-up reductions in drug injection, multiperson reuse of syringes and needles, multiperson reuse of other injection equipment (cookers, cotton, rinse water), and crack use. The studies also showed significant intervention effects in promoting entry into drug treatment and increasing needle disinfection. Although drug users also significantly reduced sex-related risks and increased condom use, the majority still practiced unsafe sex. One quasi-experimental study found that reductions in injection risk led to significantly reduced HIV seroincidence among outreach participants. Few investigators looked at dosage effects, but two reports suggested that the longer the exposure to outreach-based interventions, the greater the reductions in drug injection frequency. CONCLUSIONS: Accumulated evidence from observational and quasi-experimental studies strongly indicate that outreach-based interventions have been effective in reaching out-of-treatment IDUs, providing the means for behavior changes and inducing behavior change in the desired direction. The findings provide sound evidence that participation in outreach-based prevention programs can lead to lower HIV incidence rates among program participants.