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expert reaction to two new papers – investigating frequency of e-cigarette use and smoking reduction or cessation, and investigating frequency and type of e-cigarette use and quitting smoking

The relationship between e-cigarette use and smoking cessation or reduction has been explored in two papers published in the journals Addiction and Nicotine & Tobacco Research. The authors of the first paper report that daily use of e-cigarettes appears to be associated with reducing but not quitting smoking at follow-up after one year, while the authors of the other paper report that different types of e-cigarette have different effects on likelihood of quitting smoking, with the tank models (but not cigalike models) appearing to be associated with quitting cigarette smoking. The SMC also held a briefing with the authors of these papers.


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

“These two large surveys confirm that using e-cigarettes can help smokers reduce their cigarette consumption, and that some smokers may need to use e-cigarettes for a number of months or longer before they manage to stop smoking altogether. Finding out how to encourage more smokers to make the switch is an important research priority.”


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

“These two new studies make valuable contributions to the growing literature on e-cigarettes. Most previous studies have been cross-sectional surveys using broad definitions of use, whereas these new studies are longitudinal in nature so are more able to follow up individuals. Commonly previous studies have asked whether e-cigarettes have ever or recently been used, and have made broad assumptions about their impact on quit attempts and success in stopping smoking on that basis. Most previous studies have also not differentiated between types of e-cigarettes, whereas the second of these studies does investigate that aspect.

“What this new research tells us is what e-cigarette users already know. The type of device, how often it is used, and how much nicotine it contains, all matter. Some devices will be effective to help smokers to quit and others less so. Future studies need to maintain this focus and not treat all e-cigarettes, or all users, the same.”


Prof. Martin McKee, Professor of European Public Health, London School of Hygiene & Tropical Medicine, said:

“In the absence of definitive evidence from controlled trials of whether electronic cigarettes are effective as cessation aids (with the recent Cochrane review noting the poor quality of evidence), the paper by Brose et al. provides some additional insights. As the authors note, their data have many limitations, including self-selection and a considerable loss to follow-up, so that the numbers available for key analyses are small. There are also challenges in defining patterns of use of electronic cigarettes. On the other hand, this study does, at least to some extent, address the serious weaknesses of much earlier research that was quoted to support greater use of electronic cigarettes. The authors examine several end points. From a public health perspective, the only important one is complete cessation. For some important health outcomes such as cardiovascular disease, there are still considerable risks from smoking even one or two cigarettes per day and several very large studies showing no overall health benefit of reducing smoking, with the benefits only in those who quit entirely1. Indeed, one of the main concerns of those sceptical about electronic cigarettes is the potential for dual use in those who might otherwise have quit. Unfortunately this paper gives us little reassurance. Given the small sample size, it was always going to be difficult to achieve statistical significance. Yet, that said, the point estimates suggest that daily or less than daily use of electronic cigarettes is, if anything, associated with fewer people succeeding in quitting. This certainly helps to understand the growing interest of the tobacco industry in these products.

“The linked study by Hitchman et al. might, at first sight, provide be seen as providing more reassurance, suggesting that the small group who use the tank model of electronic cigarettes achieve some success in quitting. However, as the authors note, this group differs substantially, in terms of age and education, from users of other models and while these are adjusted for in the analyses, without a randomised controlled trial it will be impossible to determine whether the association is causal. Moreover, it is only if they use these products daily that, in this small study, they appear to achieve any benefit in terms of cessation. Thus, if this really does, eventually, turn out to be a true effect, then it argues for the use of these products within a regulated cessation programme, rather than using them as a consumer good.

“Clearly, these issues need to be examined in larger studies with less loss to follow up, but they certainly serve as a very serious challenge to the view expressed stridently by the supporters of electronic cigarettes that they are some remarkable disruptive innovation that will radically change tobacco control. Given the other concerns, not addressed by this study about the toxicity of long term inhalation of nicotine and the flavourings contained in these products, it seems that the precautionary approach adopted by public health authorities in many countries remains justified.”

1.One of the largest of such studies, of over 50,000 Norwegians followed for approximately 30 years concluded that “Long-term follow-up provides no evidence that heavy smokers who cut down their daily cigarette consumption by >50% reduce their risk of premature death significantly. In health education and patient counselling, it may give people false expectations to advise that reduction in consumption is associated with reduction in harm.”


Dr Mike Knapton, Associate Medical Director, British Heart Foundation (BHF), said:

Commenting on the first paper*:

“E-cigarette use is developing rapidly and more research is needed to fully understand the potential benefits and risks to people’s health.

“This study showed that e-cigarettes did not actually increase the number of successful quitters after one year but may potentially help users to reduce smoking and make more attempts to quit.

“E-cigarettes are a nicotine product that may reduce the harm associated with smoking but there are also concerns about e-cigarette use in young people, re-normalisation of smoking, deterring successful smoking cessation and questions about the long-term safety.”

Commenting on the second paperǂ:

“This research suggests that smokers who use tanks on a daily basis may be more likely to have quit smoking after a year than those who use other types of e-cigarettes, or do not use them at all.

“This is an interesting insight although the original survey was carried out in 2012 and may not reflect current use.

“As the use of e-cigarettes grows rapidly, with an estimated 2.1 million users in the UK, understanding the relationships between e-cigarette use and smoking cessation is critical in moving towards a smoke-free world.”


* ‘Is use of electronic cigarettes while smoking associated with smoking cessation  attempts, cessation and reduced cigarette consumption? A survey with a 1-year follow-up’ by Leonie Brose et al. published in Addiction on Tuesday 21 April 2015.


ǂ ‘Associations between e-cigarette type, frequency of use, and quitting smoking: findings from a longitudinal online panel survey in Great Britain’ by Sara Hitchman et al. published in Nicotine & Tobacco Research on Tuesday 21 April 2015. 


All our previous output on this subject can be seen at this weblink:


Declared interests

Prof. Peter Hajek: “I have no links with any tobacco or e-cigarette manufacturers. My research into the safety and effects of e-cigarettes is funded by UKCTAS, MHRA and NIHR.”

Prof. Linda Bauld chaired the programme development group on tobacco harm reduction that was responsible for producing guidance on harm reduction for the National Institute for Health and Care Excellence (NICE) in 2013.

Dr Mike Knapton has no personal conflicts of interest but the BHF is a funder of ASH, ASH Wales, and ASH Scotland and run No Smoking Day.  BHF also part-funded this research – but had no active involvement in the research other than funding.

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