Meier 2017.

Study characteristics
Methods	Design: Randomized cross‐over trial (e‐cig vs placebo) Recruitment: via local media outlets Setting: Community, USA Study start date/Study end date: Not specified.
Participants	Total N: 24 Inclusion criteria: ≥ 18, People who smoke daily (≥ 10 cpd) Not interested in quitting in next 30 days English‐speaking Interested in using EC Exclusion criteria: Using cessation meds Use of ECs in last 6 m Exhaled CO < 6 ppm, History of CV trauma or uncontrolled hypertension Pregnant Inclusion based on specific population characteristic: No 25% women; mean age 48.5; mean cpd 16.3; FTND not reported Motivated to quit: No (eligibility criteria was to not want to quit in next 30 days) E‐cigarette use at baseline: 8/24 (33%) had previously tried an EC, avg 9.4 months since last use, avg length of use 3.6 days
Interventions	EC: Cig‐a‐like Smoked “as usual” for 1 week followed by 2 weeks of either placebo or active 1st generation EC BluCig starter kit with up to 7 cartridges (prefilled, with either active 16 mg or 0 mg nicotine solution) Participants were instructed “this e‐cig may or may not contain nicotine; we ask that you try it at least once, but use it however you like; smoke regular cigarettes as you wish.” Shown how to charge the device and sampled the product during the visit. Provided a handout on how to use the product (e.g., switching cartridges) and general information about ECs
Outcomes	1 week in each condition, in person Adverse events and biomarkers: Adverse events, not clear how collected Exhaled CO Other outcomes measured: Vaping Regular smoking Perceived reward from ECs Intentions/confidence to quit Cotinine Withdrawal symptoms
Study funding	“..supported by grants P01 CA138389, P30 CA138313 (Hollings Cancer Center Support Grant) from the National Cancer Institute of the National Institutes of Health and UL1 TR000062 from the National Center for Advancing Translational Science of the National Institutes of Health. BWH was supported by K12DA031794”
Author declarations	“KMC has received grant funding from the Pfizer, Inc., to study the impact of a hospital‐based tobacco cessation intervention. He also receives funding as an expert witness in litigation filed against the tobacco industry. We have no other declarations of interests to declare”
Notes	New for 2020 update.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: “Participants were randomized to receive either an active or placebo EC first”, no further information provided.
Allocation concealment (selection bias)	Unclear risk	Refer to 'Random sequence generation'.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: “Participants and research staff conducting sessions were blinded to dose. All cartridges were pre‐loaded by the manufacturer. Labeling was removed by a research team member not involved in participant contact to mask placebo versus active ECs. We restricted flavor options to regular tobacco flavor or menthol to most closely match usual cigarette brand flavor profile and reduce unwanted variance in product”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: “Participants and research staff conducting sessions were blinded to dose. All cartridges were pre‐loaded by the manufacturer. Labeling was removed by a research team member not involved in participant contact to mask placebo versus active ECs. We restricted flavor options to regular tobacco flavor or menthol to most closely match usual cigarette brand flavor profile and reduce unwanted variance in product”
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not specified
Selective reporting (reporting bias)	Low risk	All expected outcomes reported