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expert reaction to unpublished conference presentation on nicotine e-cigarettes and clotting

An unpublished presentation*, to be given at the European Respiratory Congress (ERS) International Congress, looks at the impact of nicotine e-cigarettes on the body compared to non-nicotine e-cigarettes. 


Dr Adam Jacobs, Senior Director of Biostatistics at Premier Research, said:

“The information available lacks sufficient detail to be able to assess the research fully, and it has not been peer-reviewed or published.  So we should be extremely cautious about accepting any of the claims at face value.

“It’s hard to interpret the results, as they say nothing about their statistical methods. The authors claim statistical significance, but without knowing how the values were calculated it’s impossible to say how meaningful they are.

“It’s important to note that the researchers did not look at any clinical outcomes. The headline suggests that patients may somehow suffer from deleterious effects of blood clotting, but that is not what they have shown at all. I’m not even sure whether they have looked at the patients themselves or just at blood samples taken from the patients.

“There is no clinical outcome investigated in this study.  So the statement in the press release ‘with long-term use, [vaping] could result in heart attack or stroke’ is absolutely not supported by the study. They have investigated neither long term use nor heart attacks nor strokes.

“Overall, I don’t find this research compelling. It is based on a small sample, doesn’t investigate the clinical outcomes referred to in the press release, and is hard to assess even on its own terms because of the lack of detail in how it is described.  The suggestion that e-cigarettes ‘have similar impacts on the body as smoking traditional cigarettes’ is an extraordinary claim and this study simply does not appear to provide the extraordinary evidence to support it.” 


Dr Jamie Hartmann-Boyce, Senior Research Fellow and Director of the Evidence-Based Healthcare DPhil Programme, Centre for Evidence-Based Medicine, University of Oxford, said:

“This small study in 22 adults who smoked occasionally looked at very short-term outcomes (up to one hour) after puffing on nicotine e-cigarettes, and compared this to what happened after people puffed on non-nicotine e-cigarettes.

“The press release makes statements about long-term risks of things like heart attack and stroke, but this study did not look at these.

“In addition, this study hasn’t been published yet, which means it hasn’t been peer reviewed and data from it haven’t been provided, so it is difficult to assess what the researchers have done.

“The authors report that, unsurprisingly, puffing on nicotine e-cigarettes had a short term effect  on a number of measures – the same was not seen in people using non-nicotine e-cigarettes, suggesting the changes were due to the nicotine. This is to be expected, as nicotine is a stimulant.

“The harm from smoking cigarettes comes from the burning of tobacco, not from nicotine. Nicotine has been used safely for decades as nicotine replacement therapy in patches, gums and lozenges – and in this form is one of the most safe and effective tools for quitting smoking. Nicotine e-cigarettes are not harmless, but international scientific experts agree they are likely to be substantially less harmful than smoking. The single best thing someone who smokes can do for their health is to quit smoking, and a growing body of evidence shows nicotine e-cigarettes can help with this.

“Though the press release states that ‘e-cigarettes that contain nicotine have similar impacts on the body as smoking traditional cigarettes,’ this study only looks at a small subset of short-term measures. Results of this small, short-term study should not discourage people who smoke from switching to vaping, and certainly should not encourage anyone who vapes to switch to smoking – the two are not the same.”


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

“This conference presentation documents well-known short-term effects of nicotine, but these are not considered to be related to cardiovascular disease. Nicotine on its own, without combustion products from cigarettes, poses minimal health risks.

“Long-term users of nicotine products such as Swedish oral tobacco or nicotine chewing gum have no increased risk of heart attacks or strokes. Press releases and media stories that suggest that vaping is as dangerous as smoking because of effects like this are misleading. Smokers who switch to using e-cigarettes dramatically reduce the risks to their health.” 


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

“This study appears to demonstrate well-known effects of nicotine, which in pure form is known to have adverse effects on humans of similar magnitude to those of coffee. The study definitely does not provide evidence on the relative harms of vaping nicotine and smoking tobacco because the experiment does not appear to have made any measurements of the effect of tobacco smoking for comparison. The study conclusion, that vaping nicotine is likely to be as harmful as smoking tobacco, is therefore completely without foundation.”



* ‘Electronic cigarettes containing nicotine increase thrombotic activity and impair microcirculation’ will be presented at ERS International Congress. 


Declared interests

Dr Jamie Hartmann-Boyce: “No conflicts of interest.”

Prof Peter Hajek: “No conflict of interest.”

Dr Adam Jacobs: “I don’t have any conflicts of interests to declare.”

No others received.

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