Blog Post 1)
A new study published online today in JAMA Pediatrics2) purports to provide data showing that electronic cigarettes are “aggravating the tobacco epidemic among youth.”
The article reports the results of a cross-sectional sample of adolescents interviewed in 2011 and 2012 in the National Youth Tobacco Survey. Youths were asked to report their smoking status as well as their e-cigarette use, both any use and current use (at least once in the past month).
The study finds that e-cigarette use is associated with smoking status. In addition, e-cigarette use is associated with heavier smoking and with fewer periods of smoking abstinence.
The study concludes that “e-cigarette use is aggravating rather than ameliorating the tobacco epidemic among youths.”
(See: Dutra LM, Glantz SA. Electronic cigarettes and conventional cigarette use: a cross-sectional study. Published online March 6, 2014. JAMA Pediatr. doi:10.1001/jamapediatrics.2013.5488.)
The Rest of the Story
The authors of this study make one of the most cardinal errors in all of epidemiology. They ignore the principle that “correlation does not equal causation.”
Here, they find a correlation between e-cigarette use and higher and more sustained levels of smoking. But because this is a cross-sectional study, they cannot determine which came first. In other words, what is the direction of the causal relationship? Does the e-cigarette use precede, and cause, the smoking? Or does the smoking precede, and cause, the e-cigarette use?
The problem is that in this cross-sectional study, there is no way to determine the direction of the observed relationship.
The authors admit this in the paper. They write: “This is a cross-sectional study, which only allows us to identify associations, not causal relationships.”
Furthermore, later in the paper they reinforce this point more specifically, writing: “the cross-sectional nature of our study does not allow us to identify whether most youths are initiating smoking with conventional cigarettes and then moving on to (usually dual use of) e-cigarettes or vice versa…”.
Thus, the authors readily acknowledge that it is impossible from this study to determine whether or not e-cigarettes lead to smoking or whether smoking leads to e-cigarette experimentation.
Nevertheless, this does not stop the authors from drawing a conclusion. They conclude, despite their acknowledged inability to draw such a conclusion, that: “e-cigarette use is aggravating rather than ameliorating the tobacco epidemic among youths.”
In other words, despite acknowledging that they cannot tell from their study whether e-cigarette use precedes smoking or whether smoking precedes e-cigarette use, they nonetheless draw the conclusion that e-cigarette use precedes smoking.
In my view, there is only one possible explanation for this: Dr. Glantz is no longer playing by the rules of science. He is now a man on a mission: to destroy the e-cigarette industry and to remove e-cigarettes as an option for smokers trying to quit. He has apparently drawn the pre-determined conclusion that e-cigarettes are aggravating the tobacco epidemic among youth, and he will stop at nothing to draw this conclusion and disseminate it to the public.
Apparently, the science no longer matters. You can acknowledge that a study does not allow you to determine the direction of a relationship, but then go ahead and draw such a conclusion anyway. Frankly, this is junk science, and it is just as bad as what we have attacked the tobacco industry for doing in years past.
Whether e-cigarette use precedes smoking or smoking precedes e-cigarette use is a critical question, but it is one which needs to be answered through longitudinal research. We need studies that follow the trajectory of teen tobacco/e-cigarette use over time. That is the only way to determine which comes first.
The problem with what Dr. Glantz has done is that he is already disseminating the “answer” to this important research question without having actually done the research. That obviates the need to do the research because it is too late. The answer has already been disseminated, and it is going to affect important public policy as well as clinical decisions.
Another problem with what Dr. Glantz has done is that it is fundamentally dishonest. He is essentially lying to the public about the science regarding electronic cigarettes. He knows full well - as he acknowledges in the paper - that this study provides no answer regarding whether e-cigarettes precede and lead to smoking or whether youths who are heavier and more dependent smokers are more likely to experiment with e-cigarettes. Nevertheless, he is telling the public that he has answered the question and that the answer is that e-cigarette use precedes and leads to smoking. This is tantamount to lying to the public.
The rest of the story is that this is what the tobacco industry used to do. It is not how we in tobacco control should be conducting our business.