Gateway or common liability? A systematic review and meta‐analysis of studies of adolescent e‐cigarette use and future smoking initiation

Background and Aims Studies have consistently found a longitudinal association between e‐cigarette use (vaping) and cigarette smoking. Many have interpreted such association as causal. This systematic review and meta‐analysis evaluated the plausibility of a causal interpretation by (1) estimating the effect of adolescent vaping on smoking initiation, adjusted for study quality characteristics, (2) evaluating the sufficiency of adjustment for confounding based on the social development model (SDM) and the social ecological model (SEM) and E‐value analyses and (3) investigating sample attrition and publication bias. Methods Systematic review and meta‐analysis of longitudinal studies that examined the association between e‐cigarette use at baseline and smoking at follow‐up. Participants were non‐smokers aged