White 2021.

Study name	Cigarette nicotine reduction in the presence of an alternative: investigating how cigarette nicotine content and e‐liquid content affect smoking
Methods	Design: RCT (2x2x2 design) Setting: USA
Participants	50 Inclusion criteria: daily smoker.
Interventions	All received study cigarettes and a vape pen with e‐liquid to use for 12 weeks Study cigarettes  (very low nicotine content (0.4 mg/g of tobacco)) Study cigarettes  (normal nicotine content (15.8 mg/g of tobacco; double‐blind)) Vape pen ‐ E‐liquids contained low nicotine (0.3%) levels of nicotine Vape pen ‐ E‐liquids contained moderate nicotine (1.8%; open‐label) Flavours: only tobacco/menthol flavour options Flavours: tobacco/menthol, mint, fruit and dessert flavour options
Outcomes	CPD during week 12 was the primary outcome.
Starting date
Contact information
Notes	Study recruitment ended early due to concerns about pending regulations and the availability/relevance of the study vaping products

BMI: body mass index; CAR: continuous abstinence rate; CO: carbon monoxide; COPD: chronic obstructive pulmonary disease; cpd: cigarettes per day; CVD: cardiovascular disease; EC: electronic cigarette; ECG: electrocardiogram; FTND: Fagerström Test for Nicotine Dependence; NNAL: carcinogen found in tobacco smoke; NRT: nicotine replacement therapy; PP(A): point prevalence (abstinence); QoL: quality of life; TQD: target quit date; wk: week; yr: year