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expert reaction to study of people who vape and smoke (dual users) and quitting smoking

A study published in Tobacco Control looks at dual use of e-cigarettes and cigarettes and quitting.


Dr Sarah Jackson, Principal Research Fellow, UCL Tobacco and Alcohol Research Group, University College London (UCL), said:

“This study does not assess whether vaping helps smokers to quit. Rather, it describes patterns of smoking and vaping over time among a group of adults who both smoked cigarettes and vaped (‘dual users’) when the study started. The results show that most dual users are likely to carry on smoking or continue to both smoke and vape – that is, most dual users don’t quit smoking. This is consistent with what we’d expect, given that not all of these people are even trying to quit, and that even among those who do try to stop smoking the majority are unsuccessful (because quitting smoking is incredibly difficult).

“If we want to know whether vaping helps people to stop smoking, we need to look at differences in quit rates between smokers who vape and smokers who don’t vape. Other studies have done this, using observational and experimental study designs, and have shown that smokers who try to quit with an e-cigarette are more likely to be successful. At the population level, increases in e-cigarette use among smokers have been associated with increases in overall quit rates (i.e., the proportion of smokers quitting) and quit success rates (i.e., the proportion of quit attempts that are successful).”


Prof John Britton, Emeritus Professor of Epidemiology, University of Nottingham, said:

“In my view the findings here are predictable in a model in which smokers who try vaping do it for two principal reasons – to reduce or quit smoking (whether for health, social or cost reasons) and to manage short periods of smoking abstinence during the day.

“Smokers who are highly motivated to quit or are less dependent, and who try vaping, are likely to quit more easily and hence don’t meet the entry criteria for this study, which by definition and sampling reasons will be biased towards people who have been dual using for some time. Those who find it harder to quit tobacco but find that vaping helps to reduce smoking will be more likely to remain dual users. Those who are vaping as a means to manage temporary abstinence don’t even intend to quit, so will remain dual users.

“So the design of this study selects people who find it hard to quit, or don’t want to. In that context the good news is that some at least manage it. What the study can’t tell us is whether more smokers who become dual users manage to quit than smokers who do not. Evidence with NRT used in this way shows that those smokers are indeed more likely to quit and I see no reason why vaping should be any different.

“So the message of this paper is that quitting is difficult, but that vaping may help you to achieve it. To say that vaping stops you quitting in the ‘real world’ is wrong.”


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

“The conclusion that vaping ‘did not contribute to substantial smoking cessation at the population level’ does not follow from the data. The study excluded vapers who stopped smoking and only looked at those who did not manage this and became dual users. Despite this selection of those who did not benefit fully straight away, over 25% of dual users in fact did quit smoking later.

“There is a serious methodological problem in excluding smokers who switched completely to vaping, and only assessing the efficacy of vaping for smoking cessation on those who became dual users. It is like removing the best apples from a fertilised orchard, measuring what is left, and declaring that fertilisation had no effect. 

“The press release by Tobacco Control is particularly misleading. It claims that dual use is harmful, when actually it is associated with reduced smoking and later quitting and so it is in fact beneficial. It also asserts that the study found that vaping doesn’t help smokers quit more easily, when the paper makes no such claim.”


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

“This study cannot address the issue of whether vaping e-cigarettes helps or hinders smoking cessation at a population level, however tentatively such a conclusion may be phrased – so it is surprising to see such a claim being made by a serious scientific journal. Everyone in the study was vaping and smoking at the start of the study and so there was no comparator group of people smoking but not vaping. Even if such a group had been included, teasing apart any possible effect of vaping from pre-existing characteristics of smokers is extremely difficult.

“As it happens, well-conducted population-level studies have found that people who use e-cigarettes when trying to quit smoking are more likely to succeed, and that increased use of e-cigarettes over time in the population has been associated with an increase in cessation rates. This confirms the very strong evidence from randomised trials where smokers are randomly allocated to receive e-cigarettes or products such as nicotine patches, gum and lozenges; these studies clearly show e-cigarettes to be superior.

“The claim in the press release that the data show that using e-cigarettes may not aid cessation in population samples is particularly surprising given that daily users of e-cigarettes at the start of the study were more likely to quit smoking within the next two years than non-daily users. This is in the opposite direction of what they appear to be claiming.”



Trajectories of ENDS and cigarette use among dual users: analysis of waves 1 to 5 of the PATH Study’ by Nandita Krishnan et al. was published in Tobacco Control at 23.30 UK time on Tuesday 13th December 2022.




Prof Robert West: “In the past 5 years I have consulted for Pfizer that makes the anti-smoking drug, varenicline.”

Dr Sarah Jackson: “I have no conflicts of interest.”

Prof Peter Hajek: “No conflict of interest.”

Prof John Britton: “No conflicts.”

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