Tashkin 2001.

Methods	BUPROPION Randomized controlled trial Setting: multi‐centre, USA Recruitment: advertisements for volunteers
Participants	404 smokers with mild to moderate COPD. (Excludes 7 early drop‐outs who did not take any study medication); 45% F, av. age 53‐54, av. CPD 28, 18% in Bupropion group and 23% in Placebo had a history of depression.
Interventions	1. Bupropion SR 300 mg/day for 12w from 1w before TQD 2. Placebo All participants had brief face‐to‐face counselling at each clinic visit (weeks 1‐7, 10, 12), telephone counselling 3 days after TQD
Outcomes	Abstinence at 52w, sustained from w4 (unpublished data from GSK, Lancet paper reports 6m data) Validation: CO =< 10 ppm at each visit
Notes	12m unpublished data used from 2003/2. ITT population defined as those taking at least one dose of study medication. Funding: Glaxo Wellcome Inc
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomised as per code provided by Glaxo Wellcome, using block sizes of four stratified by centre. Within each block of four, two participants were assigned placebo and two bupropion SR. The randomisation codes were kept at the study sites during the trial and we instructed investigators to break the code only for a medical emergency."
Allocation concealment (selection bias)	Low risk	See above
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Double‐blind study, but further detail not provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	64% intervention and 73% control followed up at 6m. "All participants who withdrew from the study were taken to be smokers thereafter."