Heavy smokers who use both cigarettes and e-cigarettes are at greater risk of stroke, say researchers. However, the same study shows that e-cigs alone do not increase the risk of stroke at all. The US study has now been criticised for being misleading.
The study, published in American Journal of preventive medicine, is an analysis of 160,000 Americans' self-reported health status with a focus on smokers and vejpers. The age range is 18 to 44 years and the data was collected between 2016 and 2017.
The results showed that smokers and former smokers who now use vejp have almost the same risk of stroke. For the group using both e-cigs and analogue cigarettes, the risk was even higher.
"Our analysis indicates that e-cigarettes' claimed benefits over smoking are not clear," the researchers write.
But the analysis has been criticised because the risk of stroke was assessed on the basis of reported cases, without taking into account when the person had their heart attack: it may well have happened before they started using e-cigarettes. This is also something the researchers emphasise.
"The results should be interpreted with caution. We have not been able to see the timeline between smoking and e-cigarette use," the researchers write.
Incorrect conclusions
According to several leading researchers in the field of e-cigarettes and health, the current study is grossly misleading. In particular, the authors state that double vaping (e-cigs + analogue cigs) is more risky than just smoking traditional cigarettes. The authors also write that the flavours in the e-liquid may be the reason for the increased risk.
"Such a claim is grossly contradictory. Their findings clearly show that e-cigarettes alone do not lead to increased risk," says Dr Lion Shahab, an epidemiologist and public health researcher at the University of London, to the Science Media Centre.
He argues that the potentially higher risk of double-firing is more likely to be due to the fact that heavy smokers who are already at risk are also part of the group that most often uses e-cigarettes to try to cut down on smoking.
"We know from previous studies that this particular group is at increased risk from the outset as they have ingested more harmful substances through smoking over a long period of time than others. They also have a greater need for nicotine, which explains the dual use", Lion Shahab adds. Science Media Centre.
Stroke leads to vejpning
Lion Shahab's criticism is echoed by John Britton, Professor and Director of Tobacco and Alcohol Studies in London.
'This study shows that there is a link between smoking and stroke. This is well known and an entirely expected result. It also shows that vejping itself does not increase the risk of stroke. This contradicts their entire reasoning. However, we see a clear pattern of reverse correlation - those smokers who have had a stroke or feel health effects from smoking are also those who are trying to quit smoking. The study is certainly not evidence that e-cigarettes increase the risk of stroke in ex-smokers." John Britton told Science Media Centre.
Long time for vessels to heal
Previous research has shown that the risk of heart disease is immediately reduced when someone quits smoking, regardless of whether they use e-cigarettes or other nicotine products. This became clear when researchers studying a similar statistic also took into account the time elapsed after quitting smoking in relation to e-cigarette use and the timing of reported heart disease such as stroke.
"It takes a long time to get rid of the harmful effects of smoking. It is only after six years that we can expect the risk of heart disease to be at the same level as for a non-smoker. And for e-cigarette users, that risk is the same as for non-smokers, six years after quitting," the cardiologist said. Konstantinos Farsalinos who led the study.
Vejpare improved blood vessels
Similar conclusions were reached by British researchers in the autumn of 2020, according to a controlled long-term study found that that ex-smokers who switch completely to e-cigarettes have better blood vessels within a month. The study was the first of its kind. It involved 114 smokers. All had smoked at least 15 cigarettes per day for at least two years prior to the study. They were randomly divided into three groups: one group continued to smoke, two groups switched from cigarettes to e-cigarettes, one with and one without nicotine.
The study showed that the ability of the vessels to contract had increased significantly for the group that used e-cigarettes instead of cigarettes, already after one month. Together with measurements of the stiffness of the vessels, the vejp participants showed clear signs of improved vascular health compared to the group that still smoked.
