Van Staden 2013.

Study characteristics
Methods	Design: Single‐group within‐subject design Recruitment: Participants from a military hospital in South Africa Setting: South Africa Study start date/ end date: Not specified
Participants	Total N: 15, mean age 38 years, smoked 20 cpd (range 10 ‐ 30), for an average of 17 years (range 5 ‐ 27) Total N: 13 completed the study (5 women) Inclusion criteria: Adults who smoke daily, of at least 10 cpd Exclusion criteria: History of lung disease Inclusion based on specific population characteristic: No Motivated to quit: Not specified E‐cigarette use at baseline: Not specified
Interventions	EC: Cig‐a‐like Participants were asked to use an EC only for 2 weeks (i.e. no cigarettes) EC: 'Twisp eGo' cartridge 0.8 ml containing 0.0144 mg of nicotine
Outcomes	The following measurements were taken at baseline and 2‐week follow‐up: Blood pressure and pulse Arterial and venous COHb and blood oxygen saturation
Study funding	"We are grateful for the sponsorship of the eGo e‐cigarette packs by Twisp and also for the valuable advice and laboratory assistance given by Col. (Dr) J Lubbe, Chemical Pathologist, 1 Military Hospital, Pretoria with regard to the measurement of the cotinine levels. We also wish to acknowledge Professor Martin Veller for his insightful contributions during the preparation of this manuscript and also Dr Richard van Zyl‐Smith for his assistance and review."
Author declarations	"The sponsor of the Twisp e‐cigarette had no role in the design and conduction; the collection, analysis and interpretation of the study; or in the preparation, review or approval of the manuscript."
Notes	Dropouts (N = 2) were due to illness (headache and fever) and undertaking a military course associated with high stress and exposure to others smoking, making it difficult to abstain from cigarettes The paper states that the EC cartridge contained 0.8 ml of solution with 0.0144 mg of nicotine. This would be an unusually low concentration of nicotine and we have assumed an error in units where milligrams should have been grams (0.0144 grams of nicotine would make the concentration 18 mg/ml)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Prospective cohort
Allocation concealment (selection bias)	High risk	Not randomized
Incomplete outcome data (attrition bias) All outcomes	Low risk	2/15 lost to follow‐up
Selective reporting (reporting bias)	Unclear risk	Unable to determine prespecified outcomes