Friday, January 06, 2017

First Longitudinal Study to Examine Progression from Vaping to Smoking among Young People Finds No Effect of Vaping

The first longitudinal study that examines progression from vaping to smoking among young people has been published in the journal Addictive Behaviors. The study followed college freshmen at Virginia Commonwealth University for one year to examine whether vaping at baseline was associated with the progression from never smoking to ever and/or current smoking at follow-up.

(See: Spindle TR, et al. Electronic cigarette use and uptake of cigarette smoking: A longitudinal examination of U.S. college students. Addictive Behaviors 2017; 67:66-72.)

As reported by Dr. Stan Glantz, the major finding of the study was that: "controlling for a wide range of demographic and behavioral variables, ... e-cigarette users at baseline were about 3.4 times as likely to be smoking cigarettes a year later as young adults who were not using e-cigarettes."

According to Dr. Glantz, the "evidence just keeps piling up" that experimentation with e-cigarettes causes youth to become cigarette smokers.

The article itself concludes that: "Given that never-smoking participants who had tried e-cigarettes were more likely to initiate cigarette use later, limiting young adults' access to these products may be beneficial."

In other words, the paper appears to be concluding, like Dr. Glantz, that e-cigarette experimentation causes youth to become cigarette smokers.

These conclusions, if accurate, are ominous for the role of vaping as a harm reduction strategy in tobacco control because although e-cigarettes may help many smokers quit, this benefit would be largely offset if e-cigarettes also propel many youth to become smokers.

The Rest of the Story

Before you throw in the towel on the prospects for e-cigarettes as a harm reduction strategy in tobacco control, you may want to consider this:

You have only been told part of the story. There is another part to the story which is curiously omitted by Dr. Glantz and de-emphasized in the paper.

Here is the rest of the story:

The finding that "[current] e-cigarette users at baseline were about 3.4 times as likely to be smoking cigarettes a year later as young adults who were not using e-cigarettes" is just one finding in the paper. A second finding, which is actually more critical than the first and more relevant to the question of whether vaping leads youth to progress to regular cigarette smoking, is the following:

Current e-cigarette users at baseline were no more likely to progress to current smoking than young adults who were not using e-cigarettes.

Dr. Glantz doesn't even mention this key finding. While he reports the finding from the left column of Table 3 (the association between current vaping and ever use of cigarettes), he hides the finding from the right column of Table 3 (the association between current vaping and current use of cigarettes).

What this means is that all we know for sure about the young people who Dr. Glantz would have us believe have become smokers because of e-cigarettes is that they have at least once tried a cigarette, but that they have not smoked a cigarette in the past 30 days. So all these kids who Dr. Glantz would have us believe have been addicted to cancer sticks because of e-cigarettes are actually not current smokers. If the result of regular e-cigarette use is that while you may try a cigarette, one year later you end up not being a smoker, then vaping is doing no harm and e-cigarettes are not serving as a gateway to "a lifetime of addiction to smoking," as the CDC would like us to believe.

Why would someone who is reporting the results of this important study omit this critical finding, the key finding of the entire paper? Clearly, it's because that person is trying to hide that result from you. It's because, I think, the finding being hidden from you is damaging. It's damaging to a pre-determined conclusion that would be threatened if this finding were to be revealed.

Now the authors of the paper itself do not hide this finding completely, but they do de-emphasize it in three ways. First, they de-emphasize the finding by putting it in parentheses. In other words, while they highlight the "positive" finding (current e-cigarette use is associated with young adults trying a real cigarette), they mention the "negative" finding only parenthetically (current e-cigarette use is not associated with young adults becoming smokers).

The abstract reports the results as follows: "Ever use of e-cigarettes (but not current use) also increased participants' likelihood of being current smokers at time 2." The parentheses are not mine, but are in the original manuscript text.

Second, they omit the finding from the "highlights" to the paper, which reports that current e-cigarette use is associated with young people trying a cigarette, but hides the finding that it is not associated with young people actually becoming smokers. The authors also ignore this critical finding in the conclusion section of the abstract, where they conclude that limiting young adults' access to e-cigarettes may be beneficial even though they have not demonstrated any harms and in fact have produced evidence that there are no harms.

Third, the authors try to explain away this critical finding by pointing out that the estimate is unstable because there were so few kids who progressed from vaping to current smoking. In an apparent attempt to explain away the key finding of the paper, the authors emphasize that: "Indeed, only six initial nonsmokers transitioned from a time 1 current e-cigarette user into a current cigarette smoker at time 2."


And alas, that is the entire point here. Out of a sample of 3,757 college students, the investigators were only able to find six young people who transitioned from being a vaper to becoming a smoker!!!

On the other hand, there were 20 students who had used cigarettes at baseline but had ceased smoking and were using only e-cigarettes at follow-up, and there were an additional 45 students who had smoked and vaped at baseline but were only vaping at follow-up. So while e-cigarettes were associated with positive health outcomes for 65 students, they were associated with negative outcomes for just six students.

As you can see, one could easily conclude from this paper that e-cigarette use was actually beneficial to this population of college students.

I wouldn't go that far. However, I do think it is clear that the main finding of the study is that there is no evidence that vaping is causing youth to become smokers and that in fact, the paper provides strong evidence that vaping is not associated with progression to smoking. After all, only six of the 3,757 students were shown to have progressed from vaping to smoking, and those six students were no more likely to have progressed to smoking than students who were not vaping at baseline.

The rest of the story is that far from adding to the (non-existent) evidence that vaping leads youth to become smokers, this study actually provides evidence that the phenomenon of youth becoming vapers and then progressing to become smokers is actually quite rare. Thus, the study actually provides evidence that use of e-cigarettes does not lead over time to youth becoming smokers.

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