Ratner 2004.

Methods	Setting: Preadmission clinic, teaching hospital, Canada Recruitment: Smokers awaiting surgery, not selected for motivation
Participants	237 smokers; 52% F, av. age 49, av. cpd 12; 16.5% precontemplators, 35% contemplators Provider: research nurse
Interventions	Intervention: Initiated 1‐3 weeks before surgery: 15 min face‐to‐face counselling, materials, nicotine gum, quit kit, hotline number. Post‐operative visit, 9 telephone calls, weekly for 1 m, biweekly for 2 m Control: usual care
Outcomes	Abstinence at 12m (7 day PP) Validation: cotinine <100 ng/mL based on mailed 'Nicotest' strips,. Self reported non smokers failing to return strips are classified as smokers in this analysis. 'it was not possible to verify whether participants had tested their own urine'
Notes	No information on % using NRT or other medication, classified as moderate take‐up of treatment.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization
Allocation concealment (selection bias)	Low risk	Sealed envelopes opened after baseline data collection
Incomplete outcome data (attrition bias) All outcomes	Low risk	30 I & 29 C lost to follow‐up treated as smokers. 9 deaths excluded from denominators