August 17, 2017

expert reaction to study of adolescents, e-cigarettes and smoking

In new research published in Tobacco Control scientists assess whether adolescent e-cigarette use was associated prospectively with initiation or escalation of cigarette use.

Prof. Linda Bauld, Professor of Health Policy at the University of Stirling, said:

“This study does not provide evidence that using e-cigarettes causes young people to become smokers. It simply shows that some teenagers who try an e-cigarette might go on to try tobacco, and on both occasions it could be just once. If e-cigarettes were causing smoking, then the steady decline in youth smoking we’ve seen in national surveys in recent years would be reversed. But it’s not – smoking amongst young people in the UK is at an all-time low.

“Many of the reasons why this study doesn’t demonstrate that e-cigarette use causes smoking are described by the authors themselves in this carefully written article. These include the facts that: many students who participated in the baseline survey couldn’t be followed up one year later; that use of e-cigarettes was only self-reported; that important questions about e-cigarettes were not included (type of device and whether they contained nicotine); that only ‘ever use’ (experimentation) of both e-cigarettes and tobacco was measured; and that the study took place at a time when important policies that we now have in the UK to limit youth experimentation with e-cigarettes (age of sale, advertising bans) had not yet been introduced. Other factors not measured in the study may be relevant in considering why teenagers experiment with tobacco or e-cigarettes. These include a shared tendency towards sensation seeking and risk-taking and the fact that these teenagers may engage in other risky behaviours like alcohol or drug use which weren’t considered in the article.

“There are even more reasons to be cautious. One of them is how the results are described. The authors state in their press release, for example, that among the teenagers who had never smoked but had tried an e-cigarette when they joined the study, 118 out of 343 reported smoking at least one cigarette (34%) one year later. Among the group who had not smoked and never used an e-cigarette, the figure was 124 out of 1383 (just 9%). This sounds alarming – but presented another way it quickly becomes apparent that it may not be. In fact, out of the relevant sample of over 1,700 young people, 242 had tried a tobacco cigarette at one year. 49% of these happened to have tried an e-cigarette before trying tobacco, but in fact a slightly higher proportion – 51% – hadn’t tried an e-cigarette first. Which came first – and why – might simply be a matter of chance, rather than anything else.”

Prof. Robert West, Professor of Health Psychology at UCL, said:

“The authors of this study correctly warn readers that it cannot show a causal connection between using and e-cigarette and later smoking. In the UK and the US it seems unlikely that e-cigarette use by young people is causing more of them to smoke because smoking rates in this age group now are declining at least as fast as they were before e-cigarettes started to become popular.”

Prof. John Britton, Director of the UK Centre for Tobacco & Alcohol Studies at the University of Nottingham, said:

“This paper, like the report by Miech et al also published in Tobacco Control earlier this year, demonstrates that young people experiment with things. What matters is not whether use of e-cigarettes is associated with use of tobacco, which is to be expected, but whether the availability of e-cigarettes results in more children becoming smokers than would otherwise have been the case. The very small proportions of children in this study who experiment with smoking after e-cigarettes, and the lack of evidence of escalation of smoking behaviour, are reassuring in that respect. However the acid test of whether e-cigarettes are generating new smokers will lie in the 2016 smoking, drinking and drug use survey data, which will tell us whether the sustained decline in uptake of smoking among young people over the past ten years has been sustained.”

Prof. Peter Hajek, Director of the Tobacco Dependence Research Unit, Queen Mary University of London (QMUL), said:

“People who drink white wine are more likely to also try red wine than teetotallers and kids who like superhero comics also try superhero films, whether their friends do the same or not. Common sense would not suggest that this shows gateway effects.

“To be fair, the authors seem aware that the obvious explanation of their finding is that kids who try smoking are the same kids who also try vaping and the other way round, whatever their friends are doing. The finding that vapers with no smoking friends were more likely to try smoking later on than those whose friends smoke is most likely because among the latter, those who wanted to try smoking had tried one of their friends’ cigs already.

“The claim in the BMJ press release, that e-cigarettes may be prompting UK teens to try smoking, is not really justified. It also clashes with other much more relevant data that show the exact opposite: Vaping experimentation is accompanied by a decline, not an increase, in smoking in young people. Rather than leading to smoking, access to vaping seems more likely to deflect some adolescents who would have otherwise smoked and help those who already smoke to switch to a much less risky alternative.”

* ‘Do electronic cigarettes increase cigarette smoking in UK adolescents? Evidence from a 12-month prospective study’ by Mark Conner et al. published in Tobacco Control on Thursday 17 August 2017.

Declared interests

Prof. Hajek: “No conflicts of interest.”

Prof. West: “I have not and will not accept any kind of funds, payments or hospitality from companies that make e-cigarettes because of the risk of being perceived as tainted on that count. I undertake research and consultancy for companies that manufacture smoking cessation medications and licensed nicotine replacement products. My salary is funded by Cancer Research UK.”

Prof. Bauld: served as a peer-reviewer to the journal Tobacco Control. She provided comments on the original article, which were addressed by the authors in the resubmitted and published version

None others received.