Prize‐based contingency management for the treatment of substance abusers: a meta‐analysis

Aim To review randomized controlled trials to assess efficacy of a prize‐based contingency management procedure in reducing substance use (where a drug‐free breath or urine sample provides a chance of winning a prize). Methods A meta‐analysis was conducted on papers published from J anuary 2000 to F ebruary 2013 to determine the effect size of studies comparing prize‐based contingency management to a treatment‐as‐usual control condition ( k  = 19 studies). Parallel analyses evaluated the efficacy of both short‐ ( k  = nine studies) and long‐term outcomes ( k  = six studies) of prize‐based contingency management. Results The average end‐of‐treatment effect size ( C ohen's d ) was 0.46 [95% confidence interval ( CI ) = 0.37, 0.54]. This effect size decreased at the short‐term (≤3‐month) post‐intervention follow‐up to 0.33 (95% CI  = 0.12, 0.54) and at the 6‐month follow‐up time‐point there was no detectable effect [ d  = −0.09 (95% CI  = −0.28, 0.10)]. Conclusion Adding prize‐based contingency management to behavioral support for substance use disorders can increase short‐term abstinence, but the effect does not appear to persist to 6 months.