Effect of prize-based incentives on outcomes in stimulant abusers in outpatient psychosocial treatment programs: a national drug abuse treatment clinical trials network study.

CONTEXT Contingency management interventions that provide tangible incentives based on objective indicators of drug abstinence are efficacious in improving outcomes in substance abusers, but these treatments have rarely been implemented in community-based settings. OBJECTIVE To evaluate the efficacy of an abstinence-based contingency management intervention as an addition to usual care in community treatment settings. DESIGN Random assignment to usual care or usual care plus abstinence-based incentives for 12 weeks. SETTING Eight community-based outpatient psychosocial drug abuse treatment programs. PARTICIPANTS A total of 415 cocaine or methamphetamine users beginning outpatient substance abuse treatment. INTERVENTION All participants received standard care, and those assigned to the abstinence-based incentive condition also earned chances to win prizes for submitting substance-free urine samples; the chances of winning prizes increased with continuous time abstinent. MAIN OUTCOME MEASURES Retention, counseling attendance, total number of substance-free samples provided, percentage of stimulant- and alcohol-free samples submitted, and longest duration of confirmed stimulant abstinence. RESULTS Participants assigned to the abstinence-based incentive condition remained in treatment for a mean +/- SD of 8.0 +/- 4.2 weeks and attended a mean +/- SD of 19.2 +/- 16.8 counseling sessions compared with 6.9 +/- 4.4 weeks and 15.7 +/- 14.4 sessions for those assigned to the usual care condition (P<.02 for all). Participants in the abstinence-based incentive condition also submitted significantly more stimulant- and alcohol-free samples (P<.001). The abstinence-based incentive group was significantly more likely to achieve 4, 8, and 12 weeks of continuous abstinence than the control group, with odds ratios of 2.5, 2.7, and 4.5, respectively. However, the percentage of positive samples submitted was low overall and did not differ between conditions. CONCLUSION The abstinence-based incentive procedure, which provided a mean of 203 dollars in prizes per participant, was efficacious in improving retention and associated abstinence outcomes.