“By switching from cigarettes to e-cigarettes we found an average percentage point improvement of 1.5 within just one month,” said professor of cardiovascular medicine and therapeutics at Britain’s Dundee University, Jacob George, in a briefing about the study. “And to put that into context, each percentage point improvement in vascular function results in a 13% reduction in cardiovascular event rates, such as heart attack.”
Published in the Journal of the American College of Cardiology, this study will likely be scrutinized by health experts around the world, especially given recent claims. A week prior to the release of the above, research findings presented at the American Heart Association’s Scientific Sessions 2019, which to date remain unpublished in any peer-reviewed journal, suggested that e-cigarettes have a negative effect on cholesterol levels, and therefore also on heart and brain health.
The AHA findings indicated that the 45 participants who vaped, had lower total cholesterol and higher LDL (bad) cholesterol, while those who both vaped and smoked had lower “good” cholesterol levels. This is not the first time that a study is linking vaping and heart disease based solely on correlations.
This particular study found a cross-sectional association between e-cigarette use and riskier lipoprotein (cholesterol) profiles, and based solely on that cross-sectional correlation, the investigators concluded that vaping increases “bad” cholesterol levels and has a detrimental effect on cardiovascular health.
Biased studies keep extrapolating causation from correlations
Discussing the AHA findings on his blog page, Professor in the Department of Community Health Sciences at Boston University’s School of Public Health, Dr. Michael Siegel, pointed out something that all researchers should know very well.
“In a cross-sectional study, you have to be very careful in extrapolating from correlation to causation because this type of study design is very susceptible to confounding — that is, a third variable that is associated with both smoking/vaping status and cholesterol levels and makes it look like they are related but the relationship is actually driven by this third variable.”
The professor pointed out that therefore the paper provides no evidence that vaping increases cholesterol levels, and the fact that this should be so obvious to researchers indicates a bias against vaping products.
Switching to e-cigs improved endothelial function
In the current study, which took two years to complete and was funded by the British Heart Foundation charity, researchers recruited 114 long-term cigarette smokers who had smoked at least 15 cigarettes a day for at least two years. They were placed into one of three groups for a month and had vascular testing before and after. One group stuck to tobacco cigarettes, the second switched to e-cigarettes with nicotine, and the third switched to e-cigarettes without nicotine.
The results indicated that whether or not the e-cigarettes used contained nicotine, the endothelial function (a measure of how easily blood flows around the body) in those who switched from smoking, was significantly improved.
Not safe, but safer
In concluding, Professor Jacob George emphasized the fact that their study looked at the effects of vaping when compared to the ones of smoking, and therefore the findings should be considered in that context. “It is crucial to emphasize that e-cigarettes are not safe, just less harmful than tobacco cigarettes when it comes to vascular health,” George said. “They should not be seen as harmless devices for non-smokers or young people to try.”