Subtypes of Dual Users of Combustible and Electronic Cigarettes: Longitudinal Changes in Product Use and Dependence Symptomatology.

Introduction:
This text provides an analysis of the subtypes of dual users of combustible and electronic cigarettes and their longitudinal changes in product use and dependence symptomatology. The study conducted secondary analysis on 13 waves of data from 227 dual users who participated in a 2-year observational study. The k-means method for joint trajectories of cigarette and e-cigarette consumption was adopted to identify the subtypes of dual users. The time-varying effect model was used to characterize the subtype-specific trajectories of cigarette and e-cigarette dependence. The subtypes were also compared in terms of use contexts.

Key Points:

* The four clusters of dual users identified were light dual users, predominant vapers, heavy dual users, and predominant smokers.
* Heavy dual users and predominant smokers both smoked heavily at baseline, but heavy dual users were able to reduce cigarette use by maintaining vaping at the weekly to daily level.
* Predominant vapers appeared to engage in substitution, decreasing smoking and increasing e-cigarette dependence, and were more likely to live in environments with smoking restrictions.
* Environmental constraints can drive substitution behavior, and the substitution behavior is able to be sustained if people find the substitute to be effective.

Main Message:
This study characterizes subtypes of dual users based on the dynamic interactions between cigarette use and e-cigarette use as well as product-specific trajectories of dependence. The subtypes differ in not only sociodemographic characteristics but also contexts of cigarette and e-cigarette use. Higher motivation to use e-cigarettes to quit smoking and less permissive environment for smoking may promote substitution of cigarettes by e-cigarettes. The findings suggest that smoke-free indoor air policies are effective at modifying behavior and can be used to drive people to use reduced harm products, while vape-free indoor air policies are not strong enough to reduce vaping behavior. Future research is needed to investigate these patterns in larger, more diverse samples who are using current e-cigarette products.

Buu A, Tong Z, Cai Z, et al. Subtypes of Dual Users of Combustible and Electronic Cigarettes: Longitudinal Changes in Product Use and Dependence Symptomatology. Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco. 2023;25(3):438-443. doi:10.1093/ntr/ntac151