E-cigarette use is associated with other tobacco use among US adolescents.

Objectives: To examine whether tobacco initiation via e-cigarettes increases the likelihood of subsequent tobacco use among a large representative sample of US adolescents.
Methods: This study is a retrospective longitudinal analysis from a representative sample of US middle and high school students (n = 39,718) who completed the 2014 and 2015 National Youth Tobacco Survey. The adjusted odds ratios of lifetime and current use of tobacco use were estimated by logistic regression analysis while controlling for important socio-ecological factors associated with tobacco use.
Results: E-cigarette initiators were more likely to report current use of cigarettes (AOR 2.7; 1.9-4.0, p < 0.001), cigars (AOR 1.7; 1.2-2.4, p < 0.01), or smokeless tobacco (AOR 3.1; 2.2-5.4, p < 0.001), and lifetime use of the same products as well. Also, lifetime and current use of e-cigarettes significantly increased the likelihood of cigarettes, cigars, and smokeless tobacco use.
Conclusions: Initiation of tobacco via e-cigarette, lifetime, and current use of e-cigarettes are associated with higher odds of lifetime and current use of cigarettes, cigars, and smokeless tobacco. Collectively this suggests e-cigarettes may lead to an increased use of tobacco among adolescents.