Vaping and Stroke Risk: New Study Hypes the Wrong Conclusion

According to a slew of recent headlines, electronic cigarette users (vapers) are more likely than smokers to have a stroke earlier in life. “Adults who vape could suffer a stroke at least a decade younger than those who smoke tobacco,” MSN reported on Monday. “E-cigarette users have a 15% higher risk of stroke at a younger age than traditional tobacco smokers, according to preliminary findings.”

Relying on data from the National Health and Nutrition Examination Survey (NHANES) from 2015 to 2018, the researchers identified 79,825 adults with a history of stroke who also smoke and/or vape: 7,756 (9.72%) used e-cigarettes; 48,625 (60.91%) used traditional cigarettes, and 23,444 (39.37%) used both.

The study found that vapers typically suffered a stroke around 48, participants who smoked and vaped (dual users) at 50, while plain ole' smokers experienced a stroke at 59. The paper's co-author and chair of the neurology department at Brown University's Warren Alpert Medical School, Dr. Karen Furie, suggested that e-cigarettes “aren't as benign as first thought” based on the results.

We should always be open to new evidence, and vaping may indeed be more harmful than the existing data show. For now, though, there are several crucial reasons we should be skeptical of this conclusion.

Highlighting the wrong result

First problem: these “preliminary findings” haven't been published in a journal yet. The authors are scheduled to present their research next week at the American Heart Association's annual meeting, so the data haven't even been released to the public. That prohibits us (as well as the media) from drawing any firm conclusions about the study, though we can make some tentative observations based on the abstract.

While news reports focused on the alleged stroke risk of vaping, here's the most striking conclusion from the study:

Stroke was far more common among traditional cigarette smokers than e-cigarette users or people who used both, 6.75% compared to 1.09% and 3.72%, respectively.

So although vapers and dual-users who suffer strokes tend to have them earlier than smokers, their overall stroke risk is much lower. This makes sense in light of earlier research on vaping and tobacco use. Many studies have shown a strong dose-response relationship between smoking and stroke; the fewer cigarettes you smoke, the lower your risk.

Several clinical trials have found that vaping helps smokers cut their cigarette consumption, and smokers who replace some or all of their tobacco use with vaping appear to experience reduced stroke risk. [1] One 2019 clinical trial involving 114 individuals who smoked 15 or more cigarettes daily for at least two years found that switching to vaping (with or without nicotine) led to “significant improvement in vascular health within one month ...”

Considered alongside these earlier studies, the new AHA presentation, again assuming its results are valid, actually suggests that vaping, while not entirely harmless, reduces stroke risk for smokers. As this August 2017 review noted:

Although Ecs [electronic cigarettes] might pose some cardiovascular risk to users, particularly those with existing cardiovascular disease, the risk is thought to be less than that of cigarette smoking based on qualitative and quantitative comparisons of EC aerosol versus cigarette smoke constituents. The adoption of ECs rather than cigarette smoking might, therefore, result in an overall benefit for public health.

The AHA presenters rightly noted that “more research is needed to better evaluate the long-term effects of e-cigarettes and their role in heart and stroke health.” But as I've argued previously, many tobacco researchers don't seem to actually believe that statement. Instead of objectively reporting what the data show or don't show, they tend to minimize evidence indicating that vaping offers a public health benefit while trying to link electronic cigarettes to adverse outcomes, however tenuous the association may be.

With a presentation titled “E-cigarette users face 15% higher risk of stroke at a younger age than traditional smokers,” I think Dr. Furie and her colleagues have unfortunately fallen into that trap.

[Editor's note: The AHA recently announced that the researchers will not present their results.]

[1] Nicotine-containing electronic cigarettes are often defined as tobacco products. That's an erroneous definition because it would also include nicotine gums and patches, which nobody defines as tobacco products.