Balfour et al. Respond

Wasim Maziak takes issue with only one of our article’s many topics: youth vaping as a gateway to cigarette smoking. He is correct that we subject the prospective studies to greater scrutiny than we do the articles challenging them. The prospective studies constitute the gateway theory evidence base, yet they have been subjected to relatively little critical examination. Covering as much territory as does our article, we did not have space to analyze every cited article. But as with each subject we consider, we provide ample references from which readers can draw their own conclusions.

Maziak asserts that the authors “also ignored studies that addressed their critiques of the gateway effect—by having a longitudinal design, adjusting for other tobacco and substance use, and examining regular cigarette smoking rather than experimentation—and still revealed the same association.” He cites one study¹ of which we were unaware. We had found only three studies^2–4 that included other tobacco use. Only one of these⁴ also included marijuana, although solely in a sensitivity analysis in supplementary material. In the article’s text referring to this sensitivity analysis, the authors wrote that vaping-smoking “[a]ssociations decreased in magnitude with adjustment for marijuana use.”^4(p184) They failed to mention that the association with past 30-day smoking became nonsignificant. Similarly, as noted in our article, two articles by Wills et al.,^5,6 using the identical data set, demonstrate that the inclusion of marijuana and three other variables⁵ eliminates the statistically significant relationship between vaping and subsequent smoking reported in the article that omitted these variables.⁶

Maziak considers the authorship of our article “unbalanced” because we believe there is substantial evidence that vaping can help some adult smokers to quit smoking, and that this can improve public health. We provide substantial documentation. Having devoted our careers to the welfare of both youth and adult smokers, we call for a more balanced consideration of the impacts of vaping because both are important and the current fervent emphasis on youth may come at a potentially significant cost to adult smokers. The powerful influence on the media and legislators of well-funded organizations like the Campaign for Tobacco Free Kids⁷ and the Truth Initiative,⁸ singularly focused on youth vaping, belies Maziak’s claim that “adolescents are a vulnerable population without a legal and political voice.” One could argue that the marginalized populations comprising adult smokers are the vulnerable groups lacking a political voice.