Contingency Management Facilitates the Use of Postexposure Prophylaxis Among Stimulant-Using Men Who Have Sex With Men

Background.  Stimulant-using men who have sex with men (MSM) are at high risk of human immunodeficiency virus (HIV) acquisition. Contingency Management (CM) is a robust substance abuse intervention that provides voucher-based incentives for stimulant-use abstinence. Methods.  We conducted a randomized controlled trial of CM with postexposure prophylaxis (PEP) among stimulant-using MSM. Participants were randomized to CM or a noncontingent "yoked" control (NCYC) intervention and observed prospectively. Generalized linear models were used to estimate the effect of CM on PEP course completion, medication adherence, stimulant use, and sexual risk behaviors. Results.  At a single site in Los Angeles, 140 MSM were randomized to CM (n = 70) or NCYC (n = 70). Participants were 37% Caucasian, 37% African American, and 18% Latino. Mean age was 36.8 (standard deviation = 10.2) years. Forty participants (29%) initiated PEP after a high-risk sexual exposure, with a mean exposure-to-PEP time of 32.9 hours. PEP course completion was greater in the CM group vs the NCYC group (adjusted odds ratio [AOR] 7.2; 95% confidence interval {CI}, 1.1-47.9), with a trend towards improved medication adherence in the CM group (AOR, 4.3; 95% CI, 0.9-21.9). Conclusions.  CM facilitated reduced stimulant use and increased rates of PEP course completion, and we observed a trend toward improved adherence. Participants in the CM group reported greater reductions in stimulant use and fewer acts of condomless anal intercourse than the control group. This novel application of CM indicated the usefulness of combining a CM intervention with PEP to produce a synergistic HIV prevention strategy that may reduce substance use and sexual risk behaviors while improving PEP parameters.