Electronic cigarettes, nicotine use trends and use initiation ages among US adolescents from 1999 to 2018.

Introduction:
This text is a summary of a study examining the relationship between electronic cigarette (EC) use and cigarette smoking among adolescents. The study uses data from the National Youth Tobacco Survey from 1999-2018 to investigate trends in EC and cigarette use, as well as the ages of initiation for each product. The study also uses counterfactual models to compare actual use trends to those that would have been expected in the absence of ECs.

Key Points:

* The study found that exclusive cigarette use among adolescents has declined monotonically since 1999, while EC use has increased since its introduction in 2009.
* The EC initiation age is higher than that of cigarettes, and the age of smoking initiation has been occurring later after the appearance of ECs.
* The introduction of ECs is not likely to have increased the total prevalence of adolescent nicotine users or acted as a gateway to cigarette use.
* The study found that ECs are likely diverting adolescents from cigarettes.
* The study's findings suggest that ECs have substantial implications for harm reduction among youth.
* The study's data is cross-sectional, which limits the ability to draw causal conclusions and prevents consideration of temporal ordering of product use.
* The study's use of counterfactual models may not necessarily establish causality due to possible confounding influences.

Main Message:
The main message of this study is that ECs are not increasing the total prevalence of adolescent nicotine users or acting as a gateway to cigarette use. Instead, the study found that ECs are likely diverting adolescents from cigarettes, which have been shown to be much more harmful to health. These findings suggest that ECs have substantial implications for harm reduction among youth. However, it is important to note that the study's data is cross-sectional and that the use of counterfactual models may not necessarily establish causality. Therefore, further research is needed to confirm these findings and to examine other population-level confounders such as policies.

Foxon F, Selya AS. Electronic cigarettes, nicotine use trends and use initiation ages among US adolescents from 1999 to 2018. Addiction (Abingdon, England). 2020;115(12):2369-2378. doi:10.1111/add.15099