Lifrak 1997.

Methods	Study design: Randomized controlled trial Setting: substance abuse outpatient facility, USA Recruitment: community volunteers
Participants	69 smokers av. age 39, av. cpd 25
Interventions	Therapists: nurse practitioner for 1 and 2, clinical social worker or psychiatrist experienced in addiction treatment for 2. Both interventions included use of nicotine patch (24‐hr, 10 wks tapered dose) 1. Moderate intensity ‐ 4 meetings with nurse who reviewed S‐H materials and instructed in patch use 2. High intensity. As 1 plus 16 weekly 45‐min cognitive behavioural relapse‐prevention therapy
Outcomes	Abstinence at 12 m, 1 wk PP Validation: urine cotinine for some participants, but no corrections made for misreporting
Notes	Both interventions regarded as counselling, used in comparison of intensity.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Block randomization (block size 10)
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Some biochemical validation of abstinence, all participants had active therapy
Incomplete outcome data (attrition bias) All outcomes	Low risk	12 administrative dropouts/exclusions not included, treatment group not specified. All others included