Objective: To assess whether incentives improved treatment outcome in ambulatory cocaine-dependent patients.
Method: Forty cocaine-dependent adults were randomly assigned to behavioral treatment with or without an added incentive program. The behavioral treatment was based on the Community Reinforcement Approach and was provided to both groups. Subjects in the group with incentives received vouchers exchangeable for retail items contingent on submitting cocaine-free urine specimens during weeks 1 through 12 of treatment, while the group without incentives received no vouchers during that period. The two groups were treated the same during weeks 13 through 24.
Results: Seventy-five percent of patients in the group with vouchers completed 24 weeks of treatment vs 40% in the group without vouchers (P = .03). Average durations of continuous cocaine abstinence documented via urinalysis during weeks 1 through 24 of treatment were 11.7 +/- 2.0 weeks in the group with vouchers vs 6.0 +/- 1.5 weeks in the group without vouchers (P = .03). At 24 weeks after treatment entry, the voucher group evidenced significantly greater improvement than the no-voucher group on the Drug scale of the Addiction Severity Index (ASI), and only the voucher group showed significant improvement on the ASI Psychiatric scale.
Conclusions: Incentives delivered contingent on submitting cocaine-free urine specimens significantly improve treatment outcome in ambulatory cocaine-dependent patients.