Association between e-cigarette use and future combustible cigarette use: Evidence from a prospective cohort of youth and young adults, 2017-2019.

INTRODUCTION:A surge in popularity of e-cigarettes prompts concern given the association between e-cigarettes and future cigarette use. However, much of the evidence for this association comes from early, less efficient, and lower nicotine e-cigarettes than are available and widely used now. The goal of this study was to examine the relationship between e-cigarette use in 2018 and subsequent smoking initiation and continued e-cigarette use. METHODS:Participants included members of a national longitudinal panel of youth and young adults aged 15-27 who, in 2017, reported never having used a nicotine containing product (n = 3360). Logistic regression analyses assessed associations between participants' self-reported ever e-cigarette use in 2018 and ever cigarette use, current cigarette use, and current e-cigarette use in 2019, after controlling for demographic and psychosocial variables. RESULTS:Compared with those who still had never used an e-cigarette, those who reported ever e-cigarette use in 2018 had significantly higher odds of ever cigarette use (aOR = 7.29, 95% CI [4.10, 12.97]), current cigarette use (aOR = 8.26, 95% CI [3.17, 21.53]), and current e-cigarette use (aOR = 9.70, 95% CI [6.41, 14.69]) one year later in 2019. CONCLUSIONS:These findings show that the pod mod style, high nicotine containing e-cigarettes subject young users to the same risks of transitioning to combustible cigarettes as their earlier, less efficient predecessors. Strong regulation of all nicotine products, including e-cigarettes, is needed to prevent the trajectory of e-cigarette to cigarette use among youth and young adults.