This article reports the findings and methodology of an evaluation of the efficacy of an abstinence-based contingency management intervention as an addition to usual care in community treatment settings.
The evaluation involved random assignment to usual care or usual care plus abstinence-based incentives for 12 weeks. Eight community-based outpatient psychosocial drug abuse treatment programs were involved in the evaluation, which involved 415 cocaine or methamphetamine users beginning outpatient substance abuse treatment. 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. The evaluation measured retention, counseling attendance, total number of substance-free samples provided, percentage of stimulant-free and alcohol-free samples submitted, and longest duration of confirmed stimulant abstinence. The evaluation found that 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. The overall conclusion of the evaluation is that the abstinence-based incentive procedure, which provided a mean of $203 in prizes per participant, was effective in improving retention and associated abstinence outcomes. (publisher abstract modified)