Experts Question Recent JAMA Vape-Heart Study Results

Only days after a recent study suggested that e-cigarette use contributes to reduced heart and lung health in young adults, multiple experts are questioning the validity of its methods and findings.

The study, published in JAMA Cardiology on the JAMA Network, concluded that regular daily nicotine vape use in young adults who have never smoked combustible tobacco was associated with lower vascular function and cardiorespiratory fitness. More specifically, it suggested the findings showed e-cigarette use reduced vascular function, reduced carotid artery reactivity, and lowered peak oxygen uptake compared to non-vapers. It found the effects in these areas were comparable to those seen in tobacco smokers. A group of experts, including Dr Katherine East, Dr Eve Taylor, and Dr Harry Tattan-Birch, penned a response to the study, pointing out its limitations and criticizing the messaging. 

Dr Harry Tattan-Birch, Senior Research Fellow in the Department of Behavioral Science and Health, University College London (UCL), said of the methods used: 

“This small study draws conclusions that its design cannot support. It compares just 17 vapers, 19 smokers and 22 people who use neither at a single point in time, without adequately accounting for other differences between these groups that could explain the findings. Therefore, we cannot know whether the findings reflect effects of vaping itself or other differences between participants.” 

Dr Katie East, Associate Professor in Public Health, Brighton and Sussex Medical School, University of Brighton and University of Sussex, added:

“This study suffers from several methodological flaws. The research fails to isolate vaping from past smoking history completely, and smoking can have long-lasting cardiovascular and respiratory effects that could have exaggerated any negative impacts attributed to vaping. There were also notable asymmetries in the frequency and intensity of use between the smoking and vaping groups, such that moderate vapers (i.e., those who vape at least five days a week) who could have smoked previously were compared to established daily smokers (i.e., those who smoke at least five cigarettes per day) who had not vaped in the past three months.”

While the study was not billed as the culmination of a huge, multi-year, in-depth study of thousands of vapers and non-vapers, the headline alone was bold enough to get industry attention and mainstream media coverage. Taken at face value, the apparent limitations of the dataset and questionable conclusions may be ignored in favor of writing headlines that stoke readers’ and viewers’ fears. 

The messaging of the study came under fire, particularly as it pertains to the relative risks of vaping compared to smoking, and the harms this could do to the drive to encourage smokers to switch to vaping: 

“The authors also suggest their findings challenge the idea that vaping is a reduced-harm alternative to smoking from a cardiovascular perspective. This is a serious overinterpretation. Failing to find a statistically significant difference between just 17 vapers and 19 smokers does not mean their effects are equivalent. With such small samples, even substantial differences could easily be missed.”

“Vaping is not harmless, and people who do not smoke should not start. But this study cannot establish that vaping caused the differences observed, nor overturn the broader evidence that switching from smoking to vaping likely substantially reduces cardiovascular harm.” – Dr Harry Tattan-Birch.

“Currently in Great Britain, only 29% of adults accurately perceive vaping as less harmful than smoking. Overinterpreting such small-scale observational studies can further fuel public misperceptions of vaping, and risks discouraging adults who smoke from transitioning to a less harmful product.” – Dr Katie East

The experts’ response concluded by stating that while vaping is not risk-free, and there remain gaps in the evidence of its long-term cardiovascular and respiratory effects, one extremely small, cross-sectional convenience study cannot and should not challenge results from stronger studies on the reduced risk of vaping relative to smoking. It specifically pointed to a study of 24,000 adults that found lower cardiovascular disease incidence among exclusive vapers than exclusive smokers.