title: The Efficacy of Contingency Management on Cocaine Craving, using Prize-based Reinforcement of Abstinence in Cocaine Users.
abstract: BACKGROUND
  Contingency management (CM) is one of the most common therapies in the domain of drug addiction. This study has been carried out with the purpose of evaluating the efficacy of contingency management intervention.
  
  
  METHODS
  In an experimental design, between December 15, 2014 and November 20, 2015, fifty men (between 18 and 31 with an average age of 24.6) with a history of cocaine use, were selected voluntarily and were randomly assigned into two groups of CM and control group. The CM group were awarded coupons for negative urine tests, over a period of twelve weeks. The urine tests were taken from the participants twice per week, with cutoff concentrations for positive set at 300 ng/ml and self-reporting index of cocaine craving (response rate = 96%) were evaluated in two phase, through pretest and posttest measures. The data were analyzed by parametric covariance test. Additionally, the qualitative data, resulted from demographic measures, were coded and were analyzed with the help of an analysis instrument of qualitative data i.e. ATLAS.ti-5.2.
  
  
  RESULTS
  The primary outcome was the number of negative urine tests and the secondary outcome included the cocaine usage craving index over twelve weeks. The mean of (95% of confidence) number of negative cocaine urine tests was 15.4 (13.1-17.8) in the CM group and 19.7 (17.7-21.6) in the control group (P = 0.049). Also, results showed that CM has a significant effect on reducing craving (p<0.01).
  
  
  CONCLUSIONS
  The findings of this study, while having practical aspects in this domain, can be valuable in planning remedial procedures.
authors.affiliation: PhD. Student of Clinical Psychology, Department of Psychology, Faculty of Humanities, University of Science and Culture, Tehran, Iran.
authors.forename: Bijan
authors.initials: B
authors.lastname: Pirnia
authors.affiliation: Ph.D. of Psychology, Associate Professor, Department of Psychology, Faculty of Humanities, Tarbiat Modares University, Tehran, Iran.
authors.forename: Seyed Kazem Rasoulzadeh
authors.initials: SK
authors.lastname: Tabatabaei
authors.affiliation: M.D., Psychiatric, Associate Professor, Department of Psychiatry, Faculty of Medicine, Behavioral Research Center, Baqyiatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Tavallaii
authors.affiliation: Ph.D. of Psychology, Assistant Professor, Department of Psychology, Faculty of Humanities, University of Science and Culture, Tehran, Iran.
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Soleimani
authors.affiliation: M.D., Internist, Baharloo Hospital, Tehran, Iran.
authors.forename: Kambiz
authors.initials: K
authors.lastname: Pirnia
keywords: Behavioral therapy; Contingency Management (CM); Craving; Psychotherapy; Token economy