Wennike 2003.

Methods	Study design: RCT Location: Denmark Setting: clinic Recruitment: newspaper advertisements
Participants	N = 411 Specialist population?: no Participant characteristics: 254/411 (61.8%) female; average age: 44.5 y; average cig/day: 24; nicotine dependence: FTND 6.4 Preference for quitting abruptly versus gradually: not reported
Interventions	All participants received information on behavioural smoking reduction and the general implications of smoking and its effects on health parameters. They were asked to reduce their daily number of cigarettes as much as possible by increasing the intervals between cigarettes, or increasing the time to first cigarette in the morning, or removing habitual cigarettes. Smoking cessation was recommended as the ultimate goal throughout the study Comparator: placebo gum Modality of support: face‐to‐face Overall contact time: ranged between 2 h 15 mins and 4 h 30 mins Number of sessions: 9 Pharmacotherapy: placebo gum was provided free of charge for ad libitum use for up to 12 months Quit date set?: no Intervention: nicotine gum Modality of support: face‐to‐face Overall contact time: ranged between 2 h 15 mins and 4 h 30 mins Number of sessions: 9 Pharmacotherapy: participants who scored ≤ 5 in the Fagerström test were allocated to 2 mg nicotine gum and those scoring 6 ‐ 10 were allocated to 4 mg nicotine gum. Nicotine gum was provided free of charge for ad libitum use for up to 12 m Quit date set?: no
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 24 m Biochemical validation: exhaled CO
Funding source	Pharmacia AB, Sweden
Author conflicts of interest	Not reported
Notes	Relevant comparisons: 1) Reduction method versus reduction method (pharmacotherapy)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information given
Allocation concealment (selection bias)	Unclear risk	No information given
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: “This 2‐year, double‐blind, randomized, placebo controlled trial with parallel groups tested the efficacy and safety of nicotine gum in smoking reduction”; “The placebo gum was similar in appearance and taste, but contained no nicotine”. Comment: Does not specify who was blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence was biochemically verified
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "153 (37%) completed the 24‐month study" Comment: Therefore overall attrition was high, and was not reported split by groups