Contingency management for cocaine use in methadone maintenance patients: when does abstinence happen?

Contingency management (CM) is an efficacious intervention for cocaine abusing methadone patients, but typically only about half of patients respond. By investigating time to onset of cocaine abstinence and factors associated with abstinence, we may be able to more efficiently direct CM approaches to patients most likely to benefit. Onset of cocaine abstinence was evaluated in cocaine abusing methadone maintenance patients (N = 193) enrolled in one of three randomized clinical trials of CM. Participants received standard treatment with frequent urine toxicology monitoring or standard treatment plus CM during the trials. Slightly more than half the sample obtained at least 1 week of cocaine abstinence, and approximately a third of the sample obtained at least 4 weeks of cocaine abstinence. Discrete-time survival and hazard analyses found Weeks 1 and 2 of the intervention period had the greatest probability for the initiation of abstinence, and few participants initiated any period of abstinence after Week 4. Patients randomized to CM, those with more years of cocaine use, and those with less recent cocaine use were more likely to achieve abstinence. Overall, these results indicate onset of cocaine abstinence is likely to occur early in treatment and in individuals with less severe cocaine use. Practical implications of these results for designing and implementing CM interventions in methadone maintenance clinics are discussed.