Efficacy of contingency management in improving retention and compliance to methadone maintenance treatment: a random controlled study

BACKGROUND: Compliance with methadone maintenance treatment (MMT) in China is poor. OBJECTIVE: To evaluate the effects of adjunctive contingency management (CM) on the efficacy of methadone maintenance treatment (MMT) in patients with opioid dependence. HYPOTHESIS: A 12-week prize-based contingency management (CM) intervention can increase the retention and compliance of heroin abusers to standardized MMT programs in Shanghai. METHODS: 160 heroin-dependent patients from three voluntary MMT clinics in Shanghai were randomly assigned to a treatment as usual group (MMT, n=80) and an intervention group (MMT+CM, n=80). Daily use of methadone was recorded and urine drug tests were conducted weekly during the first 12 weeks and then at week 16, week 20 and week 24. RESULTS: The 12-week retention rates for the intervention (MMT+CM) and treatment-as-usual (MMT) groups were both quite high: 87.5% and 86.2%, respectively. The average durations of using methadone in the two groups were equal (70 days versus 71 days, respectively). There was a non-significant increase in the mean longest drug-free period (7.4 weeks versus 6.5 weeks) and in the mean number of negative urine tests (7.9 versus 7.6). Secondary analysis of the 24-week outcomes (12 weeks after termination of the adjunctive CM treatment) also found no significant differences between the groups. Among those who remained in the program the severity of addiction as assessed by the Addiction Severity Index decreased dramatically over the 24 weeks but, again, there were no significant differences in the addiction measures between those in the intervention group and those in the treatment-as-usual group. CONCLUSION: Prize-based CM is not effective in improving the retention and compliance of heroin abusers to MMT in Shanghai. The main reasons for failure to replicate western studies were the unexpectedly high baseline rates of compliance in this sample (86%) and the relatively weak financial incentives provided by the CM program. CM programs are context dependent so a careful preliminary situational analysis is needed to determine their potential effectiveness at a particular site and to identify the types of incentives (prizes) that will effectively encourage behavioral change in the target participants.