Assessment of the so-called “gateway effect” based on electronic vapour product classifications
Since electronic cigarettes (e-cigs) became popular as alternatives to conventional cigarettes, with subsequent market growth amongst smokers, there is currently a debate as to whether e-cigs may be a "gateway" to conventional cigarette smoking or not. Such fears are related to the possibility that prior use of e-cigs could conceivably result in conventional cigarette smoking initiation amongst never smokers. Although the common definition of a “gateway effect” is based on the concern that current use of a potential low-risk product could facilitate the use of higher-risk products in the future, there is actually no agreed method for assessing a "gateway effect" for e-cigs. Consequently, this creates a lack of clarity and confusion among researchers, politicians, media, vapers and smokers, which often leads to misleading study interpretations and conclusions being drawn.
To this end, we have described a framework based on product classification to assess any so-called “gateway effect”: ‘alternative product’, ‘transition product’, ‘substitution product’ or ‘gateway product’.
Each of these four categories corresponds to a different probability of a consumer switching from a potential low-risk product to a high-risk product, and vice versa, based on the motives for using them. Using an approach such as dynamic population modelling, it will be possible to classify e-cigs in one of these four product categories and thereby to assess whether e-cigs are a ‘gateway’ or a ‘roadblock’ to conventional cigarette smoking. Here we describe this innovative approach.