William A. Zule, DrPH¹, Kara S. Riehman, PhD¹, Georgiy Bobashev, PhD², and Wendee Wechsberg, PhD³. (1) Substance Abuse Treatment Evaluations and Interventions, RTI International, PO Box 12194, 3040 Cornwallis Drive, Research Triangle Park, NC 27709-2194, 919.485.2797, zule@rti.org, (2) Statistics Program, Research Triangle Institute, 3040 Cornwallis Rd, Bldg. Cox 1, Research Triangle Park, NC 27709, (3) Substance Abuse Treatment Evaluations and Interventions, Research Triangle Institute, PO Box 12194, 3040 Cornwallis Drive, Research Triangle Park, NC 27709-2194

There is growing concern regarding the sexual diffusion of HIV from core groups such as injecting drug users (IDUs) and men who have sex with men (MSM) to more general population groups (i.e. non-injectors and heterosexuals). This presentation explores event level predictors of IDUs engaging in unprotected intercourse (vaginal or anal) with non-injectors. Results are based on baseline data from out-of-treatment IDUs participating in an ongoing HIV prevention study in North Carolina. The first 71 participants in the study were 73% male, 73% African-American, 21% non-Hispanic white, and 6% Hispanic, with a mean age of 40 years. Ninety-four percent were heterosexual, 3% gay, and 3% bisexual. In the past 30 days, 83% reported using heroin and 45% had used crack. HIV prevalence was 9%. At their last sexual encounter, 44% had sex with a casual partner, 77% used drugs, 51% of partners used drugs, 62% reported >5 years age difference between themselves and their partners, and 38% reported having unprotected intercourse with a non-injector. In exploratory analyses, age differential > 5 years, partner type, being African-American, and having a crack-using partner were associated with unprotected intercourse with a non-injector. Findings from multivariate analyses based on a larger sample will also be presented. The high prevalence of IDUs reporting unprotected intercourse with non-injectors increases the possibility of diffusion of HIV from IDUs to non-injectors. Additional research is needed to identify circumstances associated with HIV transmission and guide intervention development to prevent widespread diffusion of HIV from IDUs to other groups.

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