By Brad Rodu
In an extraordinary leap of logic, a report in Tobacco Control links “ever” use of e-cigarettes – even a single experimental puff – to subsequent “ever” use of cigarettes. Researchers from the University of Hawaii, University of Connecticut and the Norris Cotton Cancer Center in New Hampshire base their findings on surveys of high-school students on the Hawaiian island of Oahu. The journal’s press release publicizing the study quotes first author Thomas Wills: “Teens who use e-cigarettes are more likely to try the real thing a year later.”
In the journal and the release, the terms “use” and “try” are used interchangeably to make the case for the e-cigarette as a gateway to smoking. The news media eagerly took the bait (see here and here).
Wills defines an e-cig user as anyone who “smoked [sic] e-cigarettes 1-2 times…3-4 times…a few e-cigarettes a year…a few e-cigarettes a month…a few e-cigarettes a week…[or] every day.” In other words, students who ever took a puff on an e-cig were counted together with students who used them more often. Wills similarly distorts the definition of cigarette smoking.
Such broad definitions are pointless from a scientific perspective, but they have one advantage: by inflating the number of users, they support a (false) linkage between e-cigs and cigarettes.
If we use the generally accepted definition for adolescent substance use – i.e., used in the past month – the prevalence of e-cig use was 8 percent and cigarette use was 4 percent during the study. By manipulating the definitions, Wills claims that 31 to 38 percent of students used e-cigs and 15 to 21 percent of students smoked.
Those numbers are then used to suggest that students who were e-cigarette users were two to four times more likely to use cigarettes at the one-year follow-up than students who had never used an e-cigarette. This is not a surprising finding. As I have repeatedly noted (here and here): “If you have ever used one tobacco product, you are likely to have ever used another.”
Even if we accept the authors’ definitions and analysis, the majority of new smokers at follow-up were students who had never used e-cigarettes, as shown in this table.
|Number of Ever Cigarette Smokers at Follow-Up Among Never Smokers at Baseline, According to E-Cigarette Use|
|E-Cigarette Use at Baseline (n)||Percent Smoking at Follow-up||Number|
|Never (926)||5 percent||46|
|Ever 1-2 times (60)||14||8|
|Ever 3-4 times (82)||11||9|
|More often (73)||19||14|
The bottom line: although “ever” e-cig users were more likely to ever use a cigarette than “never” e-cig users, the numbers still show that most new “ever” users of cigarettes at follow-up (46 of 77) were teens who had never used an e-cig.
Another flaw in the Tobacco Control article is that the authors write that they completed a “[l]ongitudinal school-based survey with a baseline sample of 2,338 students (9th and 10th graders…) in Hawaii…in 2013…and followed up 1 year later…” (The number was repeated in the journal’s press release). That is, in fact, a gross overstatement, as there was only complete follow-up information for 1,302 students. Since, of those, 161 had used cigarettes at baseline, my results in the table above are based on 1,141 students from Table 2 of the publication. However, Wills’ results are based on only 1,070 students.
A co-author of the article, James Sargent, was cited in this blog last year for co-authoring a “fatally flawed” gateway article about youth e-cig use. My examination of that study revealed similar problems with defining “ever” or current use. The first author of that study, Brian Primack, is quoted in a Reuters’ story about the current study, as is Adam Leventhal, first author on a third flawed gateway study.
I have described how the National Institutes of Health is spending hundreds of millions of dollars to fund anti-tobacco research. These studies are prime examples. Primack reported that his work was supported by $1.3 million in grants from the NIH’s National Cancer Institute; Leventhal listed NCI grants totaling nearly $13 million; the Wills study acknowledges a $660,000 NCI grant.
Taxpayers continue unwittingly to finance an ill-conceived battle against tobacco harm reduction.