Huber 2003.

Methods	Study design: Randomized controlled trial Country: Germany Recruitment: Community volunteers
Participants	174 smokers 55% women, av. age 38, av. cpd 28 Therapists: experienced counsellors, each took 2 groups in each condition
Interventions	1. 5 x 90‐min weekly meetings. Included contracting, reinforcement, relaxation, skills training, nicotine gum 2. Same schedule of meetings, 45 mins only, focus on sharing experiences. Nicotine gum 3. As 1, no nicotine gum. Not included in meta‐analysis
Outcomes	PPA at 12 m Validation: CO ≤ 4 ppm
Notes	Included in 2009 update. No non‐group control, in comparison 2.1.2
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomized, method not described
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Biochemical validation of abstinence
Incomplete outcome data (attrition bias) All outcomes	Low risk	31 people attending 2 or fewer meetings not included in analysis. Said to be evenly distributed. Later dropouts included as smokers