Tseng 2016.

Study characteristics
Methods	Design: 2‐arm; double‐blind placebo‐controlled RCT Recruitment: Advertisements placed in Craigslist as well as flyers distributed on the street and placed in New York City venues with details for how to contact study staff. Setting: Community, USA Study start date: July 2014 – 2015 (month unclear); Study end date: Not specified
Participants	Total N: 99 (100 were randomized but 1 participant randomized to the control arm was found to be ineligible between randomization and baseline) N per arm: Nicotine EC: 50; Placebo EC: 49 Inclusion criteria: age 21–35; daily smoker; smoked ≧ 10 cigarettes a day (verified by a CO level of ≥ 8 ppm); interested in reducing cigarette consumption; able to provide consent; had a cell phone and was willing/able to receive text messages and counselling on their cell phone; willing to use an EC for 3 weeks Exclusion criteria: pregnant and/or breastfeeding; history of asthma, other airways diseases, or heart disease; currently using smoking cessation medications (including other forms of NRT, bupropion, or varenicline), or enrolled in a smoking cessation programme or another cessation trial; use of EC in the past 14 days or any other tobacco products (pipe, cigar, cigarillos, snuff, chewing tobacco, rolling tobacco, or hookah/shisha) in the past 30 days; moderate to severe drug use disorder defined as a score of ≥ 5 on the Drug Abuse Screening Test‐10 and/or a hazardous or active alcohol use disorder defined as at least 7 for men and at least 5 for women on the Alcohol Use Disorders Identification. Inclusion based on specific population characteristic: Young adults 32.3% women; mean age 28.43; mean cpd 14.33; FTND not measured but time to first cigarette was measured categorically. The mode category was 6‐30 mins (39/99; 41.5%) Smoking behavioural dependence scale (11 items): mode category ‘Moderate’ (51/99; 51.5%) Motivated to quit: Readiness to quit (1 – 10 scale, 1 – 8 apply to current people who smoke): 5.57 ± 1.49 E‐cigarette use at baseline: No use of e‐cigs in past 14 days (eligibility criterion)
Interventions	EC: Cig‐a‐like E‐cigarette details: 3 weeks of disposable 4.5% nicotine NJOY, King Bold (NJOY, Inc, Scottsdale, AZ) which resemble conventional cigarettes. NJOY also manufactured the non‐nicotine placebo EC. Both nicotine and placebo ECs were tobacco‐flavoured. The products were purchased by the investigators and provided to the participants free of charge Other stop‐smoking pharmacotherapies: None Behavioural support: Prior to receiving the ECs, participants were required to complete a 20‐ to 30‐minute telephone counselling session with a trained tobacco cessation Counsellor. The purpose of the telephone counselling was to review current smoking patterns and offer behavioural and environmental change strategies. These included specific smoking reduction options, such as eliminating cigarettes at work and in the home, carrying only those cigarettes needed for that day, dropping cigarettes associated with less intense triggers first, avoiding smoking triggers, and other strategies to manage urges. 18 participants were asked to reduce the number of cigarettes smoked daily by at least 50% of the total number of cigarettes smoked per day at baseline. To mimic real‐life EC use, minimum EC use instruction was provided. Participants were encouraged to replace cigarettes with as much or as little use of an EC as needed in order to reduce nicotine withdrawal symptoms
Outcomes	Week 1, 3 Cessation: Not applicable Adverse events and biomarkers: adverse events and symptoms related to EC use Other outcomes measured: self‐reported reduction of at least 50% in the number of cpd percentage reduction in number of cpd Use of ECs satisfaction with ECs
Study funding	“This work was supported by the National Center for Advancing Translational Sciences at the National Institutes of Health (grant number UL1TR000038).”
Author declarations	“None declared”
Notes	Study listed as ongoing study NCT02628964 in the 2016 review update
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “computer generated”
Allocation concealment (selection bias)	Unclear risk	Quote: “…was concealed from research assistants. Blinding of the allocation of nicotine or placebo EC was ensured by the identical appearance of the ECs”. However, not enough information given on how allocation was concealed at the point of randomization
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: “Blinding of the allocation of nicotine or placebo EC was ensured by the identical appearance of the ECs”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Blinding of the allocation of nicotine or placebo EC was ensured by the identical appearance of the ECs”
Incomplete outcome data (attrition bias) All outcomes	Low risk	Nicotine EC lost to follow‐up: 10/50; Placebo EC lost to follow‐up: 10/49
Selective reporting (reporting bias)	Low risk	All expected outcomes reported