June 26, 2020

expert reaction to review of the effects of tobacco cigarettes, e-cigarettes and waterpipe use on the body and clinical outcomes

A review, published in the European Heart Journal, looked at he effects of tobacco cigarettes, e-cigarettes and waterpipe use on the body and clinical outcomes.

Prof John Britton, Director of the UK Centre for Tobacco & Alcohol Studies and Consultant in Respiratory Medicine, University of Nottingham, said:

“This paper provides an unsystematic overview on evidence relating to the likely relative risks of nicotine use, and of questionable reliability: for example, that e-cigarette use increases the risk of chronic obstructive pulmonary disease by 194% but COPD is a disease with a lead time of decades, so to attribute a risk directly to e-cigarettes – which have been widely used for less than a decade and are almost exclusively used by former smokers – is inappropriate.”

Dr Nick Hopkinson, Reader in Respiratory Medicine at Imperial College London, said:

“Most users of e-cigarettes are doing so in order to cut down or quit smoking to reduce the risk to their health. In the UK, of the 3.6million people who vape 54% have quit smoking completely https://ash.org.uk/media-and-news/press-releases-media-and-news/in-2019-around-half-as-many-britons-now-vape-as-smoke-and-the-majority-are-ex-smokers/  . The harmful chemicals present in cigarette smoke are either absent from e-cigarette vapour or present at much lower levels, which is why reports like “Nicotine without the smoke” https://www.rcplondon.ac.uk/projects/outputs/nicotine-without-smoke-tobacco-harm-reduction from the Royal College of Physicians support vaping as a means of reducing an individual’s harm from smoking.

“In this review the search strategy used to identify papers is not defined so it is not clear if it is a systematic review of all the evidence. There are also a number of reasons to be cautious about measuring risk in this area and the figure in the paper runs the risk of misleading people.

1. Most of the illnesses or disease events seen in people who vape e.g myocardial infarction or COPD are likely to be due to their past smoking history, not their use of an e-cigarette.

2. People who need to use a substitute source of nicotine (i.e. an e-cigarette) to quit may have smoked more intensely than those who were able to quit without using an aid which also makes comparisons difficult.

3. The important comparison for individuals is between carrying on smoking or switching to vaping, as that is the choice that most people are making in relation to e-cigarette use, rather than between vaping and nothing.

“It is important to note that the best evidence around vaping and blood vessel function is that in people who switch from smoking to vaping there is a substantial improvement in endothelial function.  https://www.onlinejacc.org/content/74/25/3112

“No serious commentator claims that vaping is completely harmless, but the hazard compared to smoking is much lower. In the long term smokers who have switched to vaping should be encouraged to quit vaping too, though not at the expense of going back to smoking. Non-smokers should avoid vaping.

Prof Jacob George, Professor of Cardiovascular Medicine and Therapeutics, University of Dundee, said:

“Firstly, this publication cannot be described a study. It is a clinical review of the available evidence. It does not provide de novo evidence on its own. Secondly, the authors correctly state that in terms of comparative risks of tobacco cigarettes are significantly greater than electronic cigarettes and the available evidence on the risk of e-cigarettes on lung cancer is not sufficient to draw any robust conclusions. What we cannot say for certain, and the study does not provide further clarity on either, is how much of the effects seen in electronic cigarette smokers are due to prior tobacco cigarette use. No study so far has accurately and absolutely quantified prior impact of tobacco cigarette smoking on vascular dysfunction in individual e-cigarette users as we know that most electronic cigarette smokers are former users of tobacco cigarettes and a number are dual users also. Disentangling this from the distinctive impact of e-cigarettes on vascular function is still required to fully understand the risks versus the benefits of e-cigarettes, which on a comparative basis contains significantly fewer than the 7000 harmful chemicals present in every tobacco cigarette that is smoked.” 

Prof Jamie Brown, Deputy Director of the Tobacco and Alcohol Research Group, University College London (UCL), said:

“This review appears to replicate the finding that e-cigarettes are substantially less harmful than cigarettes without being safe. There is now a huge number of studies on e-cigarettes, which makes an exact quantification of the risks difficult. To provide confidence, it is crucial to be transparent and systematic about how studies are selected and graded. The approach taken by this clinical review is unclear. The last 2016 Cochrane review on e-cigarettes found no evidence that smokers who used e-cigarettes for two years or less had increased health risks compared to smokers who did not use e-cigarettes. An update is due in the autumn.

“There is no direct evidence yet on COVID-19 and e-cigarettes:  https://www.qeios.com/read/UJR2AW.5 (Note: JB is an author and this is a preprint, which is not yet peer-reviewed).

“The WHO advice on vaping and COVID-19 is at odds with Public Health England https://www.gov.uk/government/publications/covid-19-advice-for-smokers-and-vapers/covid-19-advice-for-smokers-and-vapers.”

‘Effects of tobacco cigarettes, e-cigarettes and waterpipe smoking on endothelial function and clinical outcome’, by Thomas Münzel et al. was published in European Heart Journal on Friday 26 June at 00:05 UK time.

DOI:10.1093/eurheartj/ehaa460

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

www.sciencemediacentre.org/tag/covid-19

Declared interests

Dr Nick Hopkinson: Dr Hopkinson is the Medical Director of the British Lung Foundation And Chair of Action on Smoking and Health

Prof Jacob George: I was the chief investigator of the Vesuvius Trial. I have no direct conflicts of interest to declare

Prof Jamie Brown: I have received unrestricted research funding for studies on smoking cessation from pharmaceutical companies who manufacture smoking cessation medications. I have not and will not receive funding from e-cigarettes manufacturers or the tobacco industry

None others received