title: Extended voucher-based reinforcement therapy for long-term drug abstinence.
abstract: 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.
authors.affiliation: Treatment Research Institute, 600 Public Ledger Building, 150 South Independence Mall West, Philadelphia, PA 19106, USA. ccarpenedo@tresearch.org
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Carpenedo
authors.forename: Kimberly C
authors.initials: KC
authors.lastname: Kirby
authors.forename: Karen L
authors.initials: KL
authors.lastname: Dugosh
authors.forename: Beth J
authors.initials: BJ
authors.lastname: Rosenwasser
authors.forename: Donald L
authors.initials: DL
authors.lastname: Thompson
mesh_terms: D000328:Adult; D001521:Behavior Therapy / Q000379:methods*; D003042:Cocaine / Q000652:urine; D019970:Cocaine-Related Disorders / Q000517:prevention & control* / Q000628:therapy* / Q000652:urine; D003153:Community Health Services / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D055502:Secondary Prevention; D013997:Time Factors; D014040:Token Economy
chemical_list: D003042:Cocaine