Wong 2012.

Methods	Country: Canada Double‐blind, randomized, placebo‐controlled trial
Participants	286 participants who were smokers and scheduled for elective ambulatory or inpatient general surgical, orthopaedic, urologic, plastic, gynaecologic, ophthalmologic or neurosurgical procedures (151 varenicline /135 placebo)
Interventions	Intervention: varenicline initiated 1 week before the target quit date (24 hours before surgery) and continued for a total of 12 weeks, including a 1‐week titration as follows: days 1 ‐ 3: 0.5 mg once daily; days 4 ‐ 7: 0.5 mg twice daily; and days 8 ‐ 12 weeks: 1 mg twice daily. Control: Placebo following the schedule described for varenicline above. Both intervention and control participants received 2 15‐minute standardized counselling sessions by trained research co‐ordinators. The first counselling session occurred in the preoperative clinic, the second before discharge for ambulatory participants or 24 hours after surgery for inpatients.
Outcomes	Abstinence on target quit day/at admission to hospital. 7‐day point‐prevalence abstinence rate at 12 months after start of treatment (Primary outcome for study). Also reported: 7‐day point‐prevalence abstinence rate at 3 and 6 months after the target quit date, self‐reported changes in the number of CPD, stage of change at 3, 6 and 12 months.
Notes	Perioperative complications and adverse events were recorded, as documented in hospital charts. Smoking abstinence was biochemically validated using exhaled CO and urinary cotinine.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization list.
Allocation concealment (selection bias)	Unclear risk	Stratified block randomization in blocks of 40. Participant assignments were placed in sequentially‐numbered opaque, sealed envelopes and kept at each centre by an independent research pharmacist who was not involved in participant care or outcome assessments.
Blinding (performance bias and detection bias) All outcomes	Low risk	Participants, healthcare personnel and research staff were blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Intention‐to‐treat analysis. Numbers and reasons for drop‐out similar across groups.
Selective reporting (reporting bias)	Low risk	All outcomes as prespecified in the article are reported.
Other bias	Unclear risk	666/965 eligible participants declined to participate in the study. Perioperative complications were recorded; however the authors do not present a definition of perioperative complications.

CO: carbon monoxide
 CPD: cigarettes per day
 NRT: nicotine replacement therapy
 PACU: perioperative anaesthetic care unit