Dual use of combustible and electronic cigarettes: A fine-grained naturalistic cohort study to investigate dynamic use patterns and trajectories that lead to smoking cessation

As the tobacco product landscape continues to shift, there has been a dramatic increase in poly-tobacco use, particularly the dual use of combustible and electronic (e-)cigarettes. The health implications of dual use are unclear, as are the treatment and policy decisions as to how to best manage it. On one hand, dual use has the

potential to decrease both individual and population harm, insofar that toxicant exposure is lowered and eventual cessation of combustible cigarettes becomes possible, as growing evidence suggests. However, harm reduction is maximized only when dual users transition completely away from combustible cigarette smoking, and when

that transition is sustained. Indeed, the potential benefits of e-cigarettes are unrealized if dual users fail to quit smoking. Thus, dual use has the potential to reduce or perpetuate harm. The critical difference between these two outcomes is how these harm reducing/promoting tobacco products are used interchangeably; i.e., patterns

and trajectories over time. Unfortunately, the natural course of dual use, particularly in comparison to exclusive smoking or vaping, is unclear. Cohort studies of dual use, often derived as secondary analyses from national surveillance projects with yearly assessments, suggest that, for some, dual use can be either transient or

prolonged. Almost all of these studies lack detail on anything beyond use status (using vs. not), and particularly lack detail on daily patterns of use over time. A focused and more granular assessment of dual use patterns is needed to understand who these individuals really are, and how their smoking and vaping behaviors do and do

not change over time. Within a nationally based cohort study of dual users (n=396), and exclusive users of both combustible (n=198) and e-cigarettes (n=198), natural use histories will be assessed through a combination of a) detailed daily diaries over 3 months, b) serial bursts of nightly diaries that coincide with c) episodic monthly

surveys over a 1-year follow-up, and d) biological verification of combustible cigarette smoking. Study aims are to 1) describe, and 2) compare the consistency of use behaviors over time, within and across cohorts. As a third aim, using a within-subjects approach, we aim to assess the defining day-to-day patterns of dual use that best

predict subsequent abstinence from combustible cigarette smoking. The proposed project is the largest and longest study of dual users (vs. exclusive users) ever conducted with a priori design considerations to more fully understand the complex interplay between these two products, one of which is the root cause of significant

cancer incidence and mortality, and the other is a controversial harm reduction option with fast growing population appeal. Building upon a successful program of cancer prevention research using naturalistic research designs, remote methods, and team science, the proposed study expands our foundational knowledge regarding

tobacco use behavior and cessation among and across different groups of tobacco product users. Ultimately, and regardless of outcome, our results will inform clinical and regulatory decision making of novel products that may enable or impede the proliferation and marketing of the fastest growing segment of the tobacco marketplace.