ICRF 1994.

Methods	Setting: primary care, UK Recruitment: patients registered with practice invited to join
Participants	1686 smokers (over 15 cpd)
Interventions	2 × 2 factorial design ∙ Nicotine patch and 16‐page Health Education Authority (HEA) pamphlet ∙ Placebo patch and HEA pamphlet ∙ Nicotine patch and 46‐page booklet with more detailed information on cessation with the use of patches All participants seen once by a doctor and 4 times by a nurse
Outcomes	Sustained abstinence at 12 months Validation: salivary cotinine or expired CO
Notes	Comparison between different self‐help materials Not used in meta‐analysis No clinically or statistically significant differences between materials in either patch condition
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random allocation of study numbers to intervention groups
Allocation concealment (selection bias)	Low risk	Sequential allocation of study numbers and pre‐coded packages
Blinding (performance bias and detection bias) All outcomes	Low risk	Biochemical validation; similar levels of intensity across interventions
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only early abstainers were followed up at 6 months and 12 months; 9.2% lost to follow‐up at 12 weeks All losses included as smokers