Exclusive e-cigarette use among Parisian school students

The objective of the study, conducted during 5 years among 12-19 years old secondary school students in Paris, is to compare exclusive e-cigarettes users to exclusive tobacco users. Methods: Each year from 2013 to 2017, we randomly selected classes in Paris to include approximately 3500 students. Current e-cigarette or tobacco use was defined as use in the preceding 30 days. Students completed a one-page self-reported questionnaire in school. Data were analyzed using marginal multinomial logistic regression models in which exclusive tobacco smokers served as the reference group. Results: Among the 17 435 students included, 2.3% (n=392) reported exclusive e-cigarette use, 7.9% (n=1370) exclusive tobacco use and 3.2% dual use (n=555). Compared to exclusive tobacco smokers, e-cigarette users were: - less likely to use cannabis (adjusted odds-ratio (OR) =0.12, 95%CI=0.06-0.23); - more likely to have used e-cigarettes rather than traditional tobacco at smoking initiation (OR=9.59, 95% CI=4.81-19.13); - more likely to use a water-pipe at smoking initiation (OR=2.27, 95% CI=1.23-4.20). Compared to 12-14 year olds, the probability of being an exclusive e-cigarette user decreased with age with an OR=0.28 (95% CI=0.14-0.55) among 14-16 year olds and OR=0.12 (95% CI=0.06-0.24) among ≥ 17 year olds. The probability of being an exclusive e-cigarette user was lower if the best friend smoked tobacco (OR=0.35, 95% CI=0.23-0.56). Conclusions: Teenagers who are exclusive users of e-cigarettes differ from those who use tobacco in terms of smoking trajectory and concurrent cannabis use.