The effect of higher versus lower wattage e‐cigarettes on smoking: A randomized controlled trial

AIMS: To assess whether higher wattage e-cigarettes (HWe), with improved nicotine delivery, enhance complete substitution compared with lower wattage e-cigarettes (LWe) and whether complete switching lowers exposure to a cigarette-derived lung carcinogen, using urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) as a biomarker. DESIGN: A 3-arm randomized controlled trial with a 12-week treatment period and follow-ups at 26 and 52 weeks. Participants were enrolled from June 2017 to December 2022, with all visits completed by March 2023. SETTING: Academic medical centers in the United States. PARTICIPANTS: 372 adults who smoked and were not interested in quitting [mean age = 40 years; standard deviation (SD) = 11.0; 63% female; mean cigarettes per day = 17; SD = 8.9] were randomized and comprised the analytic sample. INTERVENTION: A 12-week supply of HWe, LWe or usual brand cigarettes (UBC). MEASUREMENTS: The primary outcome was between-group differences in complete substitution rates at week 12, defined as self-reported smoking of 1 or fewer cigarettes in the past 7 days [confirmed by exhaled carbon monoxide (eCO) < 4 ppm], with missing data imputed as smoking, and self-reported use of e-cigarettes during the 7-day period. Additional outcomes included urinary NNAL through week 12. FINDINGS: At 12 weeks, complete substitution rates were 6.0% (8 of 134) with HWe and 9.0% (12 of 133) with LWe, with no statistically significant between-group difference. Complete substitution rates were 3.7% (HWe) vs. 9.0% (LWe) at 26 weeks, and 4.5% vs. 5.3% at 52 weeks, with no statistically significant between-group differences. Among those who completely switched, mean NNAL levels decreased over 12 weeks with both LWe [mean decrease: 2.4 pmol/mg creatinine; 95% confidence interval (CI) = 1.2-3.7; P = 0.002] and HWe (mean decrease: 2.3 pmol/mg creatinine; 95% CI = 1.1-3.6; P = 0.002). CONCLUSIONS: Provision of higher and lower wattage e-cigarettes to adults who smoked and were not interested in quitting resulted in comparable substitution rates. Complete switching from cigarettes to higher and lower wattage e-cigarettes reduced urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol. TRIAL REGISTRATION: NCT03113136 (ClinicalTrials.gov).