SUPPLEMENT ARTICLE Results From a Randomized Controlled Trial of a Peer-Mentoring Intervention to Reduce HIV Transmission and Increase Access to Care and Adherence to HIV Medications Among HIV-Seropositive Injection Drug Users David W. Purcell, JD, PhD,* Mary H. Latka, PhD,† Lisa R. Metsch, PhD,‡ Carl A. Latkin, PhD,§ Cynthia A. Go ´mez, PhD, k Yuko Mizuno, PhD,* Julia H. Arnsten, MD, MPH,¶ James D. Wilkinson, MD, MPH,# Kelly R. Knight, MEd, k Amy R. Knowlton, MPH, ScD,§ Scott Santibanez, MD, MPHTM,* Karin E. Tobin, PhD,§ Carol Dawson Rose, PhD, RN,** Eduardo E. Valverde, MPH,‡ Marc N. Gourevitch, MD, MPH,†† Lois Eldred, MPH, DrPH,‡‡ and Craig B. Borkowf, PhD* for the INSPIRE Study Team Background: There is a lack of effective behavioral interventions for HIV-positive injection drug users (IDUs). We sought to evaluate the efficacy of an intervention to reduce sexual and injection trans- mission risk behaviors and to increase utilization of medical care and adherence to HIV medications among this population. Methods: HIV-positive IDUs (n = 966) recruited in 4 US cities were randomly assigned to a 10-session peer mentoring intervention or to an 8-session video discussion intervention (control condition). Participants completed audio computer-assisted self-interviews and had their blood drawn to measure CD4 cell count and viral load at baseline and at 3-month (no blood), 6-month, and 12-month follow-ups. Results: Overall retention rates for randomized participants were 87%, 83%, and 85% at 3, 6, and 12 months, respectively. Participants in both conditions reported significant reductions from baseline in injection and sexual transmission risk behaviors, but there were no significant differences between conditions. Participants in both con- ditions reported no change in medical care and adherence, and there were no significant differences between conditions. Conclusions: Both interventions led to decreases in risk behaviors but no changes in medical outcomes. The characteristics of the trial that may have contributed to these results are examined, and directions for future research are identified. Key Words: HIV prevention intervention, injection drug use, randomized controlled trial, seropositive, sexual risk behavior (J Acquir Immune Defic Syndr 2007;46:S35–S47) I njection drug use is a major risk factor for transmission of HIV in the United States. Although the proportion of injection drug users (IDUs) among HIV-positive persons has decreased over time, the Centers for Disease Control and Prevention (CDC) reported that, at the end of 2004, IDUs accounted for 24% of existing AIDS cases in the United States (30% if men who have sex with men [MSM] and inject drugs are included). 1 By gender, 34% of overall AIDS cases among women and 21% among men are attributed to drug injection (29% among men if MSM IDUs are included). 1 Recent initiatives in the United States have emphasized the need to Received for publication July 20, 2006; accepted August 3, 2007. From the *Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA; †Center for Urban Epidemiologic Studies, New York Academy of Medicine, New York, NY; ‡Department of Epidemiology and Public Health, Leonard M. Miller School of Medicine, University of Miami, Miami, FL; §Department of Health, Behavior and Society, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD; k Center for AIDS Prevention Studies, Department of Medicine, University of California San Francisco, San Francisco, CA; {Division of General Internal Medicine, Department of Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY; #Departments of Pediatrics and Epidemiology and Public Health, Leonard M. Miller School of Medicine, University of Miami, Miami, FL; **Community Health Systems, University of California San Francisco School of Nursing, San Francisco, CA; ††Division of General Internal Medicine, Department of Medicine, New York University School of Medicine, New York, NY; and the ‡‡Health Resources and Services Administration, Washington, DC. Supported by the Centers for Disease Control and Prevention and the Health Resources and Services Administration. Trial registration: Behavioral Intervention Trial for HIV-Infected Injection Drug Users, NCT00146445 (available at: http://clinicaltrials.gov/ct/ show/NCT00146445?order=1). The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. The authors report no conflicts of interest in connection with this article. Correspondence to: David W. Purcell, JD, PhD, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, 1600 Clifton Road, MS E-37 Atlanta, GA 30333 (e-mail: dpurcell@cdc.gov). Copyright Ó 2007 by Lippincott Williams & Wilkins J Acquir Immune Defic Syndr  Volume 46, Supplement 2, November 1, 2007 S35 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.