Extended voucher-based reinforcement therapy for long-term drug abstinence

Objective: To determine whether longer durations of voucher-based reinforcement therapy (VBRT) increase long-term abstinence compared to standard durations. Methods: Cocaine-abusing or dependent methadone-maintenance patients (N=130) were randomized to receive either Standard (12-week; n=62) or Extended (36-week; n=68) VBRT. Participants provided 3 urine samples weekly during VBRT, and each cocaine-negative sample produced a voucher exchangeable for goods and services. Results: Extended VBRT produced longer durations of self-reported continuous abstinence during study Year 1 (M = 74 vs. 46 days; F(1,128) = 5.23, P= 0.024), but not during Year 2. However, each week of abstinence during Year 1 was associated with an increase of 9.19 days of abstinence during Year 2, regardless of study condition (t(1)=4.92, P<0.001). Conclusions: Longer-duration VBRT can increase abstinence during VBRT, but may not maintain it afterwards. However, longer during-treatment abstinence begets later abstinence suggesting that further research regarding this relationship is needed.