Okuyemi 2022.

Study characteristics
Methods	Design: RCT Recruitment: The study identified African‐American current cigarette smokers using the electronic health record in the University of Minnesota Fairview Health system. The authors sent recruitment letters that provided a brief description of the study and invited recipients who were interested in the study to contact study staff. Participants were also invited to refer contacts outside their family to the study. Setting: Study visits were conducted in the Delaware Clinical Research Unit (DCRU) through the Clinical and Translational Science Institute (CTSI) at the University of Minnesota, USA. Study start date: June 2018. Study end date September 2019. (NCT record: Start date November 15 2016. End date March 8 2019).
Participants	Total N: 234 Nicotine EC arm: 118 Non‐nicotine EC arm: 116 Inclusion criteria: 1) Self‐identification as African‐American or black, 2) smoked ⩾ 5 cigarettes daily for the past yr, smoking status confirmed by expired CO ≥ 5 ppm or positive NicAlert screen, 3) willingness to use EC, 4) 18‐79 years Exclusion criteria: 1) Recent unstable or untreated psychiatric diagnosis including substance abuse (DSM‐IV criteria), 2) EC use in the past 30 days, 3) planning to quit smoking in the next 30 days, 4) pregnancy or nursing, 5) CO was < 5 ppm and no cotinine detected in the urine Female: 43.9%. Mean age 50.8 (SD 11.2). Mean CPD 11.5 (SD 6.0) Motivated to quit: No E‐cigarette use at baseline: No
Interventions	EC: Refillable  EC with 24 mg of nicotine added. Nicotine EC rechargeable Halo G6 brand 2.4% nicotine (24 mg, equivalent to the nicotine content of combustible cigarettes) EC ‐ No‐nicotine EC rechargeable Halo G6 brand 0% nicotine (0 mg) For both groups: A free Halo G6 brand rechargeable EC starter kit with the accessories including the charger, batteries, and a 2‐week supply of liquid cartridges. The Halo G6 device was 3.3‐4.2 (average 3.7) volts. The prefilled cartomizers coil resistance was 2.2‐2.8 ohms. At the wk‐2 visit, participants received an additional 4‐wk supply of cartridges. Participants were given oral and written instructions about how to use the products.  Ad lib for 6 weeks. All participants were provided with EC by the study; menthol and non‐menthol flavoured EC cartridges were available. Participants could purchase their own if needed after 6 weeks. Participants were compensated for their time and transportation: $40 at baseline, $40 at week 2, $50 at week 6, and $20 at week 12, for a maximum of $150 over 12 weeks.
Outcomes	Baseline, 2, 6, and 12 weeks (all visits were in‐person except week 12 which was a telephone survey) Biomarkers at baseline and 6 weeks. Urinary biomarkers (NNAL, NNK) and total nicotine equivalents (TNE, total nicotine + total cotinine + total 3‐hydroxycotinine + nicotine N‐oxide). Expired carbon monoxide (CO)  Combustible cigarettes self‐reported number of cigarettes smoked per day (and baseline). EC use (Penn State EC Dependence Index) EC dependence (10‐item Penn State EC Dependence Index) Nicotine withdrawal symptoms (baseline, week 2, 6, 12) (modified Minnesota Nicotine Withdrawal (MNWS) Data collection was self‐administered and collected on electronic tablets.
Study funding	ClearWay Minnesota Grant Award #RC‐2014‐0009
Author declarations	The authors declared that they had no competing interests.
Notes	New to 2022 update
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: ”To ensure balance in the number of intervention assignments between the study groups, randomization was blocked (block size unknown to staff or investigators) by nicotine versus no nicotine e‐cigarettes.” No other information given
Allocation concealment (selection bias)	Unclear risk	No information given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Single‐blind. Interventions equally intensive
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Biomarkers measured
Incomplete outcome data (attrition bias) All outcomes	Low risk	Nicotine EC arm: 109/118 Non‐nicotine EC arm: 106/116
Selective reporting (reporting bias)	Low risk	Reported outcomes in NCT record