Evaluation of Dual Use: Real Time Reductions in Combustible Cigarette Smoking During Co-Occurring Use of E-Cigarettes A Secondary Analysis of a Naturalistic Randomized Clinical Trial.

Abstract

Introduction: The pattern and trajectory of dual use are critical to differentiating it as a health benefit vs. harm.

Methods: Based within a large, naturalistic randomized controlled trial of e-cigarette in the U.S., adults who smoke were given a 1-month sample of tank-style e-cigarette to use as they wish (n=427) or not (n=211). Analyses are restricted to participants from the e-cigarette group who became dual users by one month (DU; n=315) vs. participants in control group who exclusively used combustible cigarettes (EUCC; n=182). Primary outcomes are based on changes in combustible cigarette smoking (cigarettes per day; CPD) across daily diaries within sampling period, and at 3 and 6-month follow-up.

Results: DUs reported significantly more diary days of large smoking reduction (smoking 1-50% of baseline CPD: 23.1% of all diary days) and not smoking (5.6% of all diary days) than did EUCCs (6.8% and 1.4%, respectively) during sampling period (p's < .001). Among DUs, 18.4% reported smoking 1-50% of baseline CPD and 9.5% were not smoking at Week 12; 17.5% reported smoking 1-50% of baseline CPD and 9.2% were not smoking at Week 24. In contrast, among EUCCs, 7.1% reported 1-50% of baseline CPD at Week 12 and 1.7% were not smoking. At Week 24, 8.2% reported 1-50% of baseline CPD and 7.1% were not smoking. Among DUs, e-cigarette use days were associated with greater probability of non-smoking days (8%) than non-e-cigarette use days (3%, p <.001).

Conclusion: Compared to continued cigarette smoking, initiating dual use reduced smoking and increased cigarette-free days.

Implications: Contrary to some claims that dual use of combustible and e-cigarettes may perpetuate or even increase harmful exposure, evidence from the current analyses, collected in real time as dual use unfolds, suggest that dual use leads to significant and sustained reductions in cigarette smoking.