Electronic cigarette use and tobacco cigarette smoking initiation in adolescents. An evidence review

This systematic review of longitudinal cohort studies aimed to explore whether electronic cigarette (e-cigarette) use by adolescents in Europe and North America, who had never smoked conventional tobacco cigarettes (tobacco cigarettes) at baseline, was associated with subsequent initiation of tobacco cigarette smoking.

Nine of the 14 unique longitudinal studies with follow-up periods between 4 and 24 months were eligible for inclusion in a meta-analysis of the association between ever use of e-cigarettes and subsequent initiation of tobacco cigarette use. Based on primary study adjusted odds ratios, our meta-analysis calculated a 4.06 (95%confidence interval (CI): 3.00-5.48) times higher odds of initiating tobacco cigarette smoking for those who had ever used e-cigarettes at baseline, although the odds ratio was reduced slightly (to 3.71 times odds, 95%CI: 2.83-4. 86) when only the four high-quality studies were included. The initial meta-analysis model had a moderate to high statistical heterogeneity, sensitivity analysis restricted to high-quality studies had a low to moderate statistical heterogeneity.