Strecher 2008.

Methods	Randomised controlled trial Location: 2 HMOs: in Washington State and Michigan, USA Funding: National Cancer Institute grants. NRT was provided by GlaxoSmithKline Recruitment: participants were recruited from the memberships of 2 HMOs participating in the National Cancer Institute's Research Network: Group Health in Washington State and Henry Ford Health System in Michigan
Participants	1866 participants aged 21 ‐ 70, currently smoking at least 10 CPD, seriously considering quitting in the next 30 days, were randomised to 1 of the 16 study arms. One of the inclusion criteria was that participants were not currently enrolled in another formal smoking cessation programme or were not currently using pharmacotherapy for smoking cessation and had no medical contraindications for NRT; average age 46.3 years, 59.5% female, 78.9% white, > High School 63.8%, average CPD 21.8
Interventions	Compares variants of an Internet‐based intervention to support NRT‐assisted quit attempts Intervention: A web‐based smoking cessation programme plus nicotine patch. 5 components of the intervention were randomised using a factorial design. Intervention group  was assigned to high‐depth tailored success story, outcome expectation, and efficacy expectation messages; high personalised source; and multiple exposure to the intervention components Control: Participants in this group were assigned to low‐depth tailored success story, outcome expectation, and efficacy expectation messages; low personalised source; and single exposure to the intervention components
Outcomes	Primary outcome: self‐reported 7‐day PPA at the 6‐month post‐quit date follow‐up Secondary outcomes: programme and NRT use
Notes	Not included in comparisons as used fractional factorial design
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐based randomisation
Allocation concealment (selection bias)	Low risk	Centralised ‐ Stratified random allocation within HMO site immediately after assessment
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	76% responded to the 6‐month follow‐up. All randomised participants were included in ITT