Oncken 2015.

Study characteristics
Methods	Design: Randomized cross‐over study Recruitment: Newspaper advertisements, radio announcements, and from local general medicine practices Setting: Lab‐based study, Connecticut, USA Study start date: October 2012; Study end date: June 2015
Participants	Total N: 27 Inclusion criteria: non‐treatment‐seeking people who smoke who were willing to try EC for 2 weeks and abstain from conventional cigarette smoking 18 – 55 years of age who smoked at least 10 cpd Exclusion criteria: Pregnant Previous myocardial infarction or stroke Uncontrolled hypertension (blood pressure (BP) > 160/100) Insulin‐dependent diabetes COPD or current asthma Known allergy to propylene glycol 45% women; mean age 42; 70% white; 15% Hispanic, 15% black; mean cpd 16; 45% had tried EC at baseline, 50% smoked menthol cigarettes Motivated to quit: No E‐cigarette use at baseline: Not specified
Interventions	EC: Cig‐a‐like Prescribed Joye eGo‐C (www.joyetech.com) and e‐Juice (18 mg/mL nicotine) procured from American eLiquid (www.americanliquid.com) Cross‐over study between menthol‐flavored and non‐menthol tobacco‐flavored EC. Requested not to smoke their regular cigarettes during study period, but most (60%) reported intermittently smoking cigarettes during study
Outcomes	Follow‐up at 1 wk and 2 weeks BP, heart rate, body plethysmography, static lung volumes and airways resistance (Raw) and specific conductance (sGaw) – taken at lab visits after abstaining from EC for at least 2 hrs, then taken again after inhaling EC and repeated 5 mins later Adverse events also reported but method for measuring not stated Also measured nicotine concentrations, rates of cigarette and EC use
Study funding	This project was supported by Academic Enhancement funds from the Department of Medicine at the University of Connecticut Health Center (to CO) and the Clinical Research Center at the University of Connecticut Health Center
Author declarations	CO is currently receiving study medication (nicotine inhaler and placebo) from Pfizer pharmaceuticals for an NIH funded of nicotine inhaler for smoking cessation during pregnancy
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not stated; Quote: "Subjects were then randomly assigned to use the menthol or plain e‐cigarette cartridge for one week, switching to the other cartridge for the second week"
Allocation concealment (selection bias)	Unclear risk	No detail given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	No detail given on blinding but equal levels of support between arms, so performance bias judged unlikely
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Some subjective outcomes but equal levels of support between arms so differential misreport judged unlikely
Incomplete outcome data (attrition bias) All outcomes	Low risk	20/27 followed up
Selective reporting (reporting bias)	Unclear risk	Unable to determine prespecified outcomes