As e-cigarettes become more popular, there has been a push to understand whether they are a “gateway” to regular, combustible cigarettes.
Two recent studies on e-cigarettes as gateways to smoking in teens and young adults have made headlines. And opponents of e-cigarettes have welcomed any crude signal of gateway effects.
As a public health professor with related research and interests in tobacco policy as well as in the complex factors that influence use of tobacco/nicotine products, I want to offer some thoughts on this research. Looking for a gateway effect between e-cigarettes and smoking is understandable. But is it the best question to ask about e-cigarette use?
The Studies
These studies find evidence for a small association (or limited gateway) between e-cigarette use in nonsmokers and a progression to trying cigarettes in a one-year study period.
The more recent of the two studies was published in September 2015 (authored by Primack et al), in JAMA Pediatrics. Researchers followed 694 12-26-year-olds for a year. None had tried cigarette smoking at the study’s start, though 16 had tried e-cigarettes. (Perhaps the worthiest headline would be that only 2% of never-smokers tried e-cigarettes.)
A year later, 10% of the never-triers of e-cigarettes had taken at least one puff on a cigarette. But 38% (six of 16) of e-cigarette triers had taken at least one cigarette puff. This study focused on cigarettes and reports no information on prior hookah, cigar, marijuana, alcohol or smokeless tobacco use. If even two of the 16 were discounted because of prior use of other products, these results would likely be statistically insignificant.
The other study (authored by Leventhal et al) was published in August 2015 in JAMA. They followed 2,530 14-year-old school students for one year. None were smokers of any combustible tobacco products, including cigars, hookah and cigarettes at the start of the study, but 222 had tried e-cigarettes.
