CBT alone in cocaine-dependent patients. Following informed consent, patients completed a two-week baseline assessment. Patients were then randomly assigned to one of the two treatment arms using computerized random numbers. The allocation sequence was provided in sealed envelopes and thus blind to the researchers and patients. After group allocation, patients received a 12-week intervention phase Selleckchem VX-770 (CBT + prizeCM

or CBT alone, week 1–12) followed by a 12-week maintenance phase (CBT + prizeCM or CBT alone, week 13–24). Six months after the last visit, patients were re-invited for a follow-up assessment and received a remuneration of 20$ for their participation (week 48). Patients were excluded by the study investigator and counted as drop-outs if they were absent for 3 consecutive weeks without any excuse. Dropout patients had the possibility of receiving a standard

treatment in other treatment centers in the region of Basel. Patients received 18 manual-guided individual CBT sessions for 24 weeks, in accordance with the CBT manual by Dürsteler-MacFarland et al. (2010), as based on the CBT manual by Carroll (1998). In the first 12 weeks, the 60-min therapy sessions took place weekly and urine samples were Selleck XAV 939 collected twice weekly. In weeks 13 to 24, the therapy sessions took place every second week and urine samples were collected weekly. Urine samples were collected and analyzed before CBT sessions and performed by the same therapist. Patients received an immediate feed-back about the results of their urinalyses. Urinalyses were tested onsite for the cocaine metabolite benzoylecgonine with the drug screen from Stephany Diagnostika GmbH (Germany). Therapy sessions were conducted by qualified psychologists and psychiatrists trained in the CBT manual for cocaine dependence, not all of whom were experienced in treating substance use disorders. All sessions were rated by therapists and audiotaped and supervised

weekly to monitor adherence to protocol. To monitor clinicians’ skill level, CBT sessions were videotaped monthly and rated by masters’-level independent evaluators. Prize-based CM was performed according to the protocol by Petry (2000) for the entire 24 weeks. According to the frequency of submitted urine samples patients in the EG had the chance to earn prizes twice weekly in the intervention phase (1–12 week) and weekly during the maintenance phase (13–24 weeks). For submitting a cocaine-negative urine sample participants had the chance to earn prizes of different magnitudes. Patients could draw from a bowl with 500 chips, of which 250 were non-winning. 219 had a value of 2$ (mini prizes: food supplies or hygiene articles), 30 a value of 20$ (medium prizes: vouchers), and the jumbo prize had a value of $500 (television or holiday vouchers).