Ikonomidis 2018.

Study characteristics
Methods	Design: (acute phase) Randomized cross‐over assignment (outcomes measured within hours of the intervention and hence do not meet the criteria of 1 week or more); chronic phase: non‐randomized, single‐group assignment Recruitment: Hospital smoking cessation unit Setting: Hospital smoking‐cessation unit, Greece Study start date: 31 January 2017; Study end date: Estimated completion date: December 2021
Participants	Total N: 90 Inclusion criteria: Active conventional cigarette smoker Adults 18 to 60 years Exclusion criteria: Health condition adversely affected by smoking, history or presence of cardiovascular disease Inclusion based on specific population characteristic: No 54% women; mean age 50.2; mean cpd 23.4; mean FTND: Not reported Motivated to quit: Yes – recruited from smoking cessation unit E‐cigarette use at baseline: Not reported
Interventions	EC: not clear E cigarette details: In the chronic phase, all 70 participants were instructed to replace their conventional cigarettes (con‐cig) with an e‐cig containing nicotine (12 mg/dL (e‐cig fluid with nicotine concentration of 12 mg/mL (propylene glycol 74.3%, glycerin 20%, flavoring 4.5%, nicotine 1.2%))) for 1 month
Outcomes	1 month; Self‐report and objective measures Cessation: Self‐report cessation at 1 month. CO measured at 1 month. Cessation data not used as < 6 months Adverse events and biomarkers: Exhaled CO concentration Heart rate; blood pressure Other outcomes measured: Oxidative stress as assessed by malondialdehyde (MDA) plasma concentrations Aortic stiffness as assessed by pulse wave velocity (PWV) and augmentation index (AIX75)
Study funding	This study was supported by a grant from the Hellenic Cardiology Society and Hellenic Society of Lipidiology and Atherosclerosis.
Author declarations	None
Notes	New for 2020 update. Acute phase of trial not relevant for the review as very short‐term outcomes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not specified
Allocation concealment (selection bias)	Unclear risk	Not specified
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded and differential levels of support given
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Objective measures used for all outcomes reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	70 participants and 20 controls recruited – no dropout
Selective reporting (reporting bias)	Unclear risk	NCT record states that chronic endothelial integrity, platelet aggregation and high‐shear stress‐dependent platelet function would be assessed but is not reported in this research letter – however study estimated completion date is December 2021, so perhaps data not ready for publication or limited capacity in the research letter – not the primary publication
Other bias	Unclear risk	Few details – written as commentary. Trial registration suggests this is an ongoing study