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The use of e-cigarettes is associated with an increased risk of heart attack, heart disease and strokes, according to a study to be presented on February 6 at the International Stroke Conference of the American Stroke Association in Honolulu.
Concern about the health effects of using e-cigarettes has increased in recent years, fueled by rising popularity and the conviction that they are safe alternatives to regular cigarettes.
The consumption of e-cigarettes among students increased by 900 percent between 2011 and 2015. In 2018, there were more than 3.6 million young people in the US, including one in five students, e-cigarettes the Centers for Disease Control and Prevention. 19659008 "E-cigarettes are kind of harmless," says Paul Ndunda, author of the study and assistant professor at the School of Medicine at the University of Kansas in Wichita. "But this study and previous other studies show that although they are less harmful than regular cigarettes, their use still poses risks."
The researchers used data from the Behavioral Risk Factor Surveillance System of 2016, a telephone survey sponsored by several federal agencies, including the CDC. The survey covers people in all 50 states who are asked about risky health behaviors such as smoking and whether respondents have been diagnosed with health issues.
Of the over 400,000 respondents in 2016, 66,795 reported consuming e-cigarettes at least once and compared to non-users, e-cigarette users had a 71 percent higher risk of stroke, a 59 percent higher risk of heart attack and a 40 percent higher risk Risk of heart disease.
Ndunda says the nature of the analysis prevented the research team from accurately calculating the absolute risk of heart attack and stroke from the database.
The results have not been published in a peer-reviewed scientific journal, but Ndunda says the researchers plan to submit their findings soon.
"These results are important because they are qualitatively and quantitatively consistent with previous studies," says Stanton Glantz, a tobacco and e-cigarette researcher at the University of California, San Francisco, who was not involved in this work however, another study in which the consumption of e-cigarettes was associated with a higher risk of heart attack. "The fact that the risk factors for stroke and heart attack are not so different is the same pattern you see when smoking cigarettes, adding to the burden on this study."
Many e-cigarette consumers, however, also smoke conventional cigarettes
In fact, Ndunda found that e-cigarette consumers smoke twice as often as traditional cigarettes, compared to people who do not use e-cigarettes.
To see the health effects of consuming e-cigarettes alone, Ndunda and his colleague Drs. Tabitha Muutu compared people who had used only e-cigarettes – not conventional cigarettes – with non-smokers.
"Even in this group, stroke risk was 29 percent higher and heart risk 25 percent higher," says Ndunda. Taken together, these two analyzes indicate an additive effect of the use of e-cigarettes and conventional cigarettes.
"So if you're a dual user, and you're a lot of e-cig users, you're actually worse off," says Glantz, who found a similar additive effect in his study.
Scientists are not quite as sure as e-cigarettes lead to this higher risk.
Smoking e-cigarettes can contribute to the gradual build-up of fat deposits in the arteries, says Glantz. However, he believes that the researchers may detect a link between an increased risk of heart attacks and strokes and the use of e-cigarettes due to a more immediate effect on the cardiovascular system.
You could have this pre-existing accumulation, says Glantz. "and then you use the e-cigarette and trigger a series of inflammatory processes, the release of oxidants and things that interfere with the normal function of the blood and blood vessels and cause a heart attack or stroke."
"This study has certainly restrictions, "says Ndunda. First, this study could not distinguish between occasional use of e-cigarettes and those who smoke more frequently. "It's probably important how much you use and we could not rate it here," says Ndunda.
E-cigarettes can deliver a range of nicotine concentrations and a variety of chemical flavors, making the analysis even more complicated. The design of the study also means that only a correlation between the use of e-cigarettes and the risk and not cause and effect can be demonstrated.
Ndunda added that a study that detects e-cigarette users early and then tracks their health over a longer period of time provides a clearer picture of the effects of steam products.
Dr. Chitra Dinakar, a clinical professor of lung and intensive care medicine at the Stanford University School of Medicine, who has studied the health effects of e-cigarettes, says that this work, which only consults adults 18 and older, does not reflect the risk of stroke among younger ones users. However, she says, "This is an important issue worthy of ongoing review."
Jonathan Lambert is an intern at the Science Desk of NPR You can follow him on Twitter: @evolambert [19459029