Objective: Contingency management (CM) reduces cocaine use in methadone patients, but only about 50% of patients respond to CM interventions. This study evaluated whether increasing magnitudes of reinforcement will improve outcomes.
Method: Cocaine-dependent methadone patients (N = 240) were randomized to 1 of 4 12-week treatment conditions: usual care (UC); UC plus standard prize CM, in which average expected prize earnings were about $300; UC plus high magnitude prize CM, in which average expected prize earnings were about $900; or UC plus voucher CM, with an expected maximum of about $900 in vouchers.
Results: All 3 CM conditions yielded significant reductions in cocaine use relative to UC, with effect sizes (d) ranging from 0.38 to 0.59. No differences were noted between CM conditions, with at least 55% of patients in each CM condition achieving 1 week or more of cocaine abstinence versus 35% in UC. During the 12 weeks after the intervention ended, CM increased time until relapse relative to UC, but the effects of CM were no longer significant at a 12-month follow-up.
Conclusions: Providing the standard magnitude of $300 in prizes was as effective as larger magnitude CM in cocaine-dependent methadone patients in this study. Given its strong evidence base and relatively low costs, standard magnitude prize CM should be considered for adoption in methadone clinics to encourage cocaine abstinence, but new methods need to be developed to sustain abstinence.
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