Secades‐Villa 2014.

Methods	Randomised controlled trial Country: Spain Setting:Community‐based, conducted in Addictive Behaviors Clinic at Oviedo University
Participants	92 smokers of > 10 CPD, aged > 18, motivated to quit, recruited by flyers, local media ads and word of mouth Mean 64.1% women; mean age 45.8 (SD 12.1); mean CPD 21.7 (SD 8.7); mean FTND 5.7 (SD 1.8); CBT 35.4% in full‐time work, CBT+CM 55.8%
Interventions	1. CBT (control) group: Group‐based counselling, 5 to 6 participants. 1‐hour sessions, weekly over 6 weeks. Main technique nicotine fading, based on weekly 30% reduction, with abstinence required from week 5 onwards. Also info about tobacco, a behavioural contract, self‐monitoring, withdrawal strategies, physiological feedback, social reinforcement, relapse prevention Cotinine and CO collected twice a week, i.e. 11 samples over the 6 weeks 2. CBT + CM: As CBT, plus voucher system, beginning in week 5 CBT session; negative ≤ 80 ng/ml. First negative specimen earned 80 points (1 point = EUR 1), with a 20‐point increase for each subsequent and consecutive negative sample. Missing samples counted as negative, and missing or failed set the reward back to 80 points. Max value EUR 300 (3 consecutive negative specimens) Points could be exchanged for vouchers for “leisure activities, cinema, theatre, museums, sports events, gyms, adventure sports, meals in restaurants, training, purchases in department stores, bookshops, clothes shops and art shops, and spa and beauty services”.
Outcomes	Primary: 7‐day PPA at EoT, at 1 month and at 6 months; CA at 6 months (all 3 time point tests to be negative) Biochemical validation by CO < 4 ppm, cotinine < 80 ng/ml Secondary: Treatment retention; % attending throughout the 6‐week course Testing was twice a week, rather than daily+
Notes	New for 2015 update Funding was from Spanish Ministry of Science and Innovation grant PS12011‐22804, and predoctoral grants BP12‐037; FOundation for the Promotion of Applied Science Research and Technology in Asturias; and Spanish Ministry of Economy and Competitiveness (BES‐2012‐053988).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Eligible participants were randomly assigned …, in accordance with a computer‐generated randomization list” (p. 64)
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence biochemically validated
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Attrition at 6 months not reported (at 1 month, 10 control and 1 intervention lost to follow‐up)