Experimenting first with e-cigarettes versus first with cigarettes and transition to daily cigarette use among adolescents: the crucial effect of age at first experiment.

Introduction:
This text is a summary of a scientific study examining the relationship between e-cigarette use and daily smoking among French adolescents. The study aims to provide a more accurate estimate of the effect of experimenting with e-cigarettes on subsequent daily tobacco smoking and to investigate how the age at e-cigarette initiation affects subsequent daily smoking. The results will be discussed in the context of national specificities in terms of tobacco and e-cigarette marketing and regulation.

Key Points:

* The study used a large national representative cross-sectional sample of adolescents and a self-administered questionnaire.
* The study defined exposure as the first experimentation with either e-cigarettes or tobacco and classified subjects as exposed (e-cigarette first) and unexposed (tobacco first).
* The study handled uncertainties about the sequence of events defining exposure by defining three patterns of exposure to avoid misclassification bias.
* The study adjusted for gender, age, literacy, socioeconomic status, pre-exposure repeat school years, and experimentation with 12 other licit and illicit drugs.
* The study found that exposure reduced the risk of transition to daily smoking (RR=0.58, 95%CI=[0.54, 0.62]).
* The study also found that the effect of exposure on transition to daily smoking increased in a linear manner with age at exposure (RR=0.87, 95%CI=[0.78; 0.98] for 1 year, p<0.001).
* The study concluded that experimenting with e-cigarettes first (as opposed to tobacco first) appears to be associated with a reduction in the risk of daily tobacco smoking among French adolescents, but this risk varies negatively with age at experimentation, and early e-cigarette experimenters are at higher risk.

Main Message:
The study provides evidence that experimenting with e-cigarettes first is associated with a reduction in the risk of daily tobacco smoking among French adolescents. however, the study also highlights the importance of considering age at e-cigarette initiation, as early experimenters are at higher risk of daily smoking. The results suggest that e-cigarettes could potentially serve as a harm reduction tool for adolescents who are already experimenting with tobacco, but further research is needed to confirm these findings and to understand the long-term effects of e-cigarette use among adolescents. Regulators should take into account these findings when developing policies related to e-cigarette use and consider measures to prevent early initiation of e-cigarette use among adolescents.

Legleye S, aubin hJ, Falissard B, Beck F, Spilka S. Experimenting first with e-cigarettes versus first with cigarettes and transition to daily cigarette use among adolescents: the crucial effect of age at first experiment. addiction (abingdon, England). 2021;116(6):1521-1531. doi:10.1111/add.15330