Lee 2019.

Study characteristics
Methods	Design: Randomized controlled trial Recruitment: Recruited from motor company. Setting: Motor company, medical office in Korea Study start date: 5 January 2012; Study end date: 31 August 2012
Participants	Total N: 150 N per arm: EC: 75; NRT: 75 Inclusion criteria: Male At least 10 cpd in previous year Smoked for at least 3 years Motivate to stop smoking entirely or reduce consumption Exclusion criteria: Past history of serious clinical disease Attempted to stop smoking in past 12 months by using NRTs Inclusion based on specific population characteristic: No 0% women; mean age 42.3; mean cpd: Not reported, 1.01 packs per day; mean FTND 4.05 Motivated to quit: Yes, or to reduce E‐cigarette use at baseline: Not specified
Interventions	EC: Refillable Both arms received 50 mins education session on smoking cessation and use of smoking cessation aids in medical office (no further detail given). Asked to return to medical office every 4 weeks (to 24 weeks?) for “evaluation and counseling by an independent health practitioner” Arm 1: 50‐min education sessions on smoking cessation and the use of smoking‐cessation aids, instructed to visit the medical office each month for evaluation and counseling by a health practitioner who was unaffiliated with the study. Participants supplied with eGo‐CTM EC (nicotine 0.01 mg/mL) from Ovale in 12‐wk supply Arm 2: As (1) but instead of EC given 2 mg nicotine gum in 12‐wk supply
Outcomes	12, 24 weeks (in person) Cessation: continuous abstinence from 9 ‐ 24 weeks, exhaled CO < 10 ppm, negative urine cotinine Adverse events and biomarkers: Yes but just note ‘adverse events’ Other outcomes measured: 7‐day PPA, cigarette reduction
Study funding	“none”
Author declarations	“none declared”
Notes	Study listed as ongoing study KCT0001277 in the 2016 review update
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “computer‐generated randomization sequence with a block size of 2”
Allocation concealment (selection bias)	Low risk	Quote: “The enrolment and assignment of all subjects were performed by a clinical research coordinator not involved in the study”
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Not blinded but both interventions active with equal amounts of support, so performance bias judged unlikely
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants not blinded but results biochemically validated
Incomplete outcome data (attrition bias) All outcomes	Low risk	61/75 NRT and 71/75 EC FU at 24 weeks
Selective reporting (reporting bias)	Low risk	All prespecified outcomes reported