Randomized trial of contingent prizes versus vouchers in cocaine-using methadone patients

Contingency management (CM) interventions frequently utilize vouchers as reinforcers, but a prize-based system is also efficacious. This study compared these approaches. Seventy-four cocaine-dependent methadone outpatients were randomly assigned to standard treatment (ST), ST plus a maximum of $585 in contingent vouchers, or ST plus an expected average maximum of $300 in contingent prizes for 12 weeks. CM participants achieved longer durations of abstinence (LDA) than ST participants, and CM conditions did not differ significantly in outcomes or amount of reinforcement earned. Although long-term abstinence did not differ by group, LDA during treatment was the best predictor of abstinence at 9 months. Thus, reinforcement with prizes was similar to voucher CM in promoting LDA, which is associated with posttreatment benefits.