A landmark study, published on January 25 in the Journal of the National Cancer Institute, found no evidence that vaping is a gateway to smoking among youth. The data come from the largest, longitudinal study of youth smoking initiation -- the PATH (Population Assessment of Tobacco and Health) study -- and include two waves of observations on nearly 12,000 U.S. youth.
The surveys asked numerous questions about both vaping and smoking behavior, including the frequency of these behaviors. It also assessed numerous risk factors for smoking that can be controlled for in multivariate analyses of smoking initiation rate differences between various groups. The baseline survey was conducted in 2013/2014 and the one-year follow-up survey occurred in 2014/2015.
The main reported finding of the study was that ever use of e-cigarettes at baseline is a risk factor for ever use of cigarettes at follow-up. This is consistent with the findings of several other studies.
The Rest of the Story
Buried deep within the article is the rather startling, but most critically relevant finding of the entire study: The investigators were unable to report a single youth out of the 12,000 in the sample who was a cigarette naive, regular vaper at baseline who progressed to become a smoker at follow-up. Why? Because the number of these youth was so small that it was impossible to accurately quantify this number.
Based on my own calculations from the data presented, out of the 12,000 youth, there were only 21 who were even past 30-day e-cigarette users at baseline (cigarette naive) who progressed even to ever smoking at follow-up. These youth reported using e-cigarettes only 1-5 days in the past 30 days at baseline, so it is not even clear that they were regular vapers. They literally could have tried an e-cigarette once 30 days earlier.
It is possible that vaping was not a gateway to smoking for any of these 21 youth, but even if it was, they represent just 0.2% of the youth population.
In addition, the study found that although ever use of e-cigarettes increased the risk of smoking initiation, recent use of e-cigarettes (within the past 30 days) did not increase the risk of smoking initiation. This finding is consistent with the hypothesis that youth who try e-cigarettes and do not particularly enjoy them such that they become regular users are the ones who are more likely to try smoking, but that youth who actually become vapers are not any more likely to subsequently try a real cigarette.
The bottom line is that despite the widespread claims that vaping is a gateway to smoking initiation among youth, the most definitive study to date of this issue fails to provide any evidence to support that contention. If anything, it provides evidence suggesting that vaping acts as a kind of diversion that can keep some youth away from cigarette smoking.
We will certainly need to await the results from future waves of the PATH study to have a clearer idea of the trajectory of youth vaping and smoking, but at the present time, I do not believe there is any evidence that vaping serves as a gateway to smoking among youth. In contrast, the evidence to date suggests that a culture of vaping is replacing, not enhancing, a culture of smoking.