Understanding Young Adult E-Cigarette Use and Dependence: Conceptualization, Measurement, and Validation

Introduction. Electronic Nicotine Delivery Systems (ENDS) use among young adults (18-24) is rapidly increasing. Identifying individuals likely to perpetuate in using ENDS is essential to understanding their risk of experiencing direct or indirect harm and to informing future intervention and policy making. Many motivational factors drive ENDS use. However, multifactorial measures indexing motives among cigarette smokers query behaviors unique to smoking that may not translate to ENDS. This research used a systematic mixed-methods approach to develop a novel measure of motives for continuation targeted at young adult ENDS users. Methods. Data for this research come from three samples of young adult ENDS users. We first conducted intensive qualitative interviews. Qualitative methods were used to identify emergent themes related to continuation. These themes informed the development of an item pool. In the following two studies we used item response theory and classical test theory methods to guide item selection. We then examined the internal consistency of the novel measure’s subscales, evaluated their independence and stability, and assessed concurrent, discriminant, incremental, and predictive validity. Results. Our analytic approach ensured that the novel measure was sensitive to differences in motives among young adults. We provided preliminary evidence of the measure’s internal consistency and validity. We also identified a subset of motives that evidenced unique covariance and should be examined further for independence and clinical utility. Conclusion. The novel measure is an internally consistent, multidimensional assessment of ENDS motives for continuation. The measure evidences incremental and predictive validity when examining tobacco use outcomes.