E-cigarettes became available in the United States during 2007. Studies using national data have found an increase in e- cigarette use among adolescents as early as 2011. In 2014, e-cigarettes became the most commonly used tobacco product among adolescents; however, little is known about its association with other tobacco products use. Therefore, the present study aimed to: 1) Examine the association between initiating tobacco use via e-cigarettes and subsequent use of other tobacco products; 2) Examine the association between the exposure to e-cigarettes marketing messages and tobacco use; 3) Describe symptoms of nicotine dependence associated with e-cigarette use, compared with cigarette and dual use of e-cigarettes and cigarettes. All aims were carried out among data from the National Youth Tobacco Survey (NYTS) 2014 and 2015. The participants of NYTS were adolescents, and they self-reported their demographic characteristics and tobacco use in an anonymous 81-item pencil-paper questionnaire.
Findings from logistic regression modeling showed that initiating tobacco use via e-cigarettes was significantly associated with subsequent current use of cigarettes (adjusted odds ratio (AOR)=2.7; 95% confidence interval [CI], 1.9-4.0), cigars (AOR= 1.7; 95% CI, 1.2-2.4), smokeless tobacco (AOR= 3.1; 95% CI, 2.2-5.4), or any tobacco products (AOR= 4.4; 95% CI, 3.5-5.6). In addition, living with someone who used e-cigarettes at home significantly increased the likelihood of using tobacco products. Notably, e-cigarette marketing exposure was significantly associated with current use of cigarettes (AOR: 1.3, 95% CI: 1.1-1.6), hookah (AOR: 1.3, 95% CI: 1.03-1.7), cigars (AOR: 1.3, 95% CI: 1.1-1.6), and polytobacco (i.e. more than one tobacco product) use (AOR: 1.8, 95% CI: 1.5-2.1). Among adolescent daily tobacco users, 35.6% of e-cigarette users and 85.3% of cigarette users reported one or more dependence symptoms. These proportions increased to 74.3% among e-cigarette and 93.3% of cigarette dual (i.e. combined) users. Strong craving was the most commonly reported symptom with a range of 16.1-58.9% among different types of smokers in the study.
In conclusion, exposure to e-cigarette marketing messages and e-cigarette use were associated with use of other tobacco products. Furthermore, e-cigarette use is addictive. Despite cigarette and dual (i.e. e-cigarette and cigarette) users being more likely to report dependence symptoms than e-cigarette users, the addictiveness of e-cigarettes occurred at appreciable rates. Collectively, the findings suggest that e-cigarettes are associated with dependence symptoms and use of tobacco products and suggest that stricter regulations are needed to prevent adolescent access to and use of e-cigarettes.