Effects of varying the monetary value of voucher-based incentives on abstinence achieved during and following treatment among cocaine-dependent outpatients.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 17222282 · doi:10.1111/j.1360-0443.2006.01664.x
What was done
A parallel-group randomized controlled trial was conducted with 100 cocaine-dependent outpatients at a university research clinic. All participants received 24 weeks of community reinforcement approach (CRA) outpatient treatment. During the first 12 weeks, participants were randomized to receive voucher-based incentives contingent on cocaine-negative urine samples set at either high monetary value (maximum $1995/12 weeks) or low monetary value (maximum $499/12 weeks). Outcomes were tracked via urine toxicology and self-report instruments through an 18-month post-treatment follow-up.
What was found
The abstract reports directional findings without providing exact figures, percentages, or test statistics. Increasing voucher value resulted in longer durations of continuous cocaine abstinence during the 24-week treatment window. Point-prevalence abstinence measured every 3 months across the 18-month follow-up remained higher in the high-value voucher arm compared to the low-value arm. Although longer in-treatment abstinence predicted subsequent abstinence during follow-up, this association attenuated over time.
Why it matters
It demonstrates a clear incentive magnitude effect in contingency management for cocaine dependence, establishing that larger monetary rewards improve both immediate and intermediate-term abstinence, even after active incentives end.
Limits
The study was conducted at a single university clinic with a modest sample size (n = 100). The abstract omits exact point estimates, effect sizes, and confidence intervals. Long-term treatment gains showed decay over the 18-month follow-up period.
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