Contingency management reduces injection-related HIV risk behaviors in heroin and cocaine using outpatients

Abstract

Intravenous drug use is a major vector of HIV transmission. We assessed whether contingency management (CM), in which participants earn reinforcers for drug abstinence, reduces HIV risk behaviors in methadone-maintained opiate- and cocaine-using outpatients. Participants ( n = 116) were randomly assigned to prize-based CM or to receipt of prize draws noncontingently on a schedule yoked to the CM group. Both groups received methadone and individual counseling throughout treatment. The HIV-Risk Taking Behaviour Scale was administered in written questionnaire form at 2-week intervals (HRBS; [Darke, S., Hall, W., Heather, N., Ward, J., & Wodak, A. (1991). The reliability and validity of a scale to measure HIV risk-taking behaviour among intravenous drug users. AIDS, 5, 181–185]). A mediation analysis was conducted to determine whether abstinence from opiates and cocaine mediated the effect of CM on HRBS scores. Changes in HRBS scores over time differed significantly by treatment ( F(9,334) = 2.4, p < 0.05), with HRBS scores decreasing over time in the CM group to a greater extent than in the noncontingent control group. Participants in the CM group had significantly lower rates of simultaneous cocaine/opiate-positive urine specimens than those in the noncontingent control group during CM treatment ( F(1,111) = 6.8, p = 0.01). The relationship between treatment condition and HRBS scores was mediated by abstinence. CM targeted toward cocaine and heroin use produces significant reductions in injection-related drug-taking behaviors associated with heightened risk for getting or transmitting HIV.