Introduction: Electronic cigarette use is significantly higher among 15-24-year-olds than in other age-groups. Electronic cigarettes, which may contain nicotine, could be a gateway to smoking initiation among young people. In this article, we reviewed the literature on smoking initiation or smoking enhancement by the use of e-cigarettes. Methods: We carried out a qualitative analysis in January 2016. We selected all longitudinal studies among adolescents or young adults using electronic cigarettes. Results: The analysis focused on 5 of the 544 articles identified, corresponding to five prospective observational studies. Four studies concluded that e-cigarette use was statistically associated with a high risk of smoking initiation. Young vapers were 8.3 (95% CI = 1.-58.6) to 12.7 (95% CI = 4.0-40.3) times more likely to initiate smoking at 1 year than non-vapers. Previous exposure to electronic cigarettes increased the risk of smoking conventional cigarettes by 14-year-old adolescents by 75% at 1 year follow-up. Conclusion: Trying e-cigarettes during adolescence or young adulthood may have contributed to starting and continuation of smoking. However, these results must be interpreted cautiously due to methodological weaknesses.
Keywords: electronic cigarettes; smoking; adolescent.