Effect of unguided e-cigarette provision on uptake, use, and smoking cessation among adults who smoke in the USA: a naturalistic, randomised, controlled clinical trial

Abstract

Background: As summarised in the most recent Cochrane review, the few clinical trials on e-cigarettes are largely focused on smoking cessation. We aimed to determine the naturalistic uptake, use, and impact of e-cigarettes among adults who may or may not want to stop smoking.

Methods: In this naturalistic, randomised, controlled clinical trial, adult smokers, across the motivational spectrum and with minimal history of e-cigarette use, were recruited online from the general community within 11 cities across the USA. Participants were randomly assigned (2:1) to either receive either a free 4-week supply of flavoured, tank-style e-cigarette, or not. E-cigarette group participants received a battery and device with up to 30 pre-filled tanks, offered among five flavours, with minimal instructions on use. The study's primary purpose was to descriptively assess naturalistic uptake and usage of the e-cigarette, and to secondarily assess its impact on smoking behavior. The latter, assessed through six months of follow-up, included: a) self-reported 7-day point prevalence abstinence, b) incidence of quit attempts, and c) smoking reduction. This trial is registered at ClinicalTrials.gov, NCT03453385.

Findings: Between 5/2018 and 3/2022, 638 adult smokers were enrolled and randomly assigned (427 in the e-cigarette group and 211 in the no-product control group). Uptake of e-cigarettes was robust: approximately 70% of participants used the product, with average usage exceeding 4 days per week during the initial 30 days. Based on an intent-to-treat approach where missing data is imputed as smoking, almost all behavioral outcomes favored the e-cigarette group relative to no-product control, including point prevalence abstinence at six months (Odds Ratio [OR] = 1.8; 95% Confidence Interval [CI] = 1.0-3.1), cumulative incidence of 24-hr quit attempts (OR = 1.5; 95% CI = 1.0-2.2), and having reduced smoking by at least 50% since baseline (OR = 1.8; 95% CI = 1.2-2.7). Results were similar under an alternative imputation.

Interpretation: Complementing cessation-focused trials, results suggest that unguided e-cigarette use also leads to smoking cessation, allaying the notion that causal effects of e-cigarettes on cessation are not reflective of real-world scenario of self-determined use. For smokers who may not be able to quit using existing pharmacologic approaches, e-cigarettes may be considered to achive that purpose.

Funding: National Cancer Institute.

Keywords: E-cigarettes; Public health; Randomised clinical trial; Smoking cessation.

Fig. 1

Consort flow of recruitment. Legend: ∗ reasons not mutually exclusive; five most common reasons shown (others available upon request).

Fig. 2

E-Cigarette uptake. Legend: ∗ non-users included (0 days). ∗∗ Users only. Solid blue bars represent percent using e-cigarette within no-product control group. Solid orange bars represent percent using e-cigarette within e-cigarette group. Solid blue lines represent number of days using e-cigarette, with non-users included, within the no-product control group. Solid orange lines represent number of days using e-cigarette, with non-users included, within the e-cigarette group. Dashed blue lines represent number of days using e-cigarette, based on users only, within the no-product control group. Dashed orange lines represent number of days using e-cigarette, based on users only, within the e-cigarette group.

Fig. 3

Cigarette and E-Cigarette dependence. Legend: ^a E-cigarette dependence within control group not shown given low uptake. Solid blue lines represent cigarette dependence scores within no-product control group. Solid orange lines represent cigarette dependence scores within e-cigarette group. Dashed orange lines represent e-cigarette dependence scores within e-cigarette group.