Friday, March 31, 2017

Vaping Opponents Have Lost Scientific Rigor; Now Concluding that E-Cigarettes Cause Heart Attacks Based on a Science Fair Project

Vaping opponents are using the results of a new "study" as evidence that vaping causes heart attacks.

Here is what my colleague Dr. Stan Glantz wrote about this "study":

"Every time I have posted a comment on a new study showing that e-cigarettes adversely affect blood vessels and blood in ways that increase risk of a heart attack, a friend and colleague who remains part of the (shrinking) collection of e-cigarette enthusiasts emails me and with he comment that, “if they are so bad where’s the evidence that e-cigarettes increase the risk of a heart attack?”  The first evidence just appeared. Using the National Health Interview Survey (NIHS), a large national survey done in the US, Nardos Temesgen and colleagues at George Washington University, found that the odds of a heart attack  increased by 42% among people who used e-cigarettes. This increase in risk was on top of the increases in risk due to any smoking that the e-cigarette users were doing. ... E-cigarette use increases the risk of a heart attack about as much as having diabetes. ... e-cigarettes represent an independent cause of heart attacks."

The Rest of the Story

Claiming that vaping causes heart attacks is a hugely important conclusion. And it is particularly important if vaping is as strong a risk factor for heart attacks as diabetes. If true, then the cardiovascular risks associated with vaping are not much lower than those associated with smoking, and the health benefits of switching from smoking to vaping are grossly overstated.

Before condemning electronic cigarettes, however, let's take a look at the rest of the story.

First, let's take a closer look at this "study." In what journal was it published?

It turns out, it was not published in any journal. It is not a peer-reviewed study.

In fact, it turns out that this study is merely an abstract that was presented by medical students at what is essentially a "science fair" project -- a "research day" in which medical students present posters summarizing their research. Now I'm not trying to demean medical student research, because that's how I started out myself, and two papers that I published as a medical student were actually quite interesting (one was the first to show that a dietary supplement - L-tryptophan - could cause pulmonary hypertension). However, these were peer-reviewed publications accepted by reputable medical journals. I wouldn't base a far-reaching conclusion on a medical school research day abstract.

Second, let's take a closer look at the study itself.

The study was merely a cross-sectional examination of the relationship between any history of a heart attack in the past and current e-cigarette use. The study did not follow people over time to see whether those using e-cigarettes were more likely to have a heart attack. Nor did it identify heart attack cases and retrospectively assess e-cigarette use. Instead, it was just a cursory, cross-sectional look at e-cigarette use prevalence among people with and without a lifetime history of a heart attack.

The study in no way proves that e-cigarettes cause heart attacks. It merely shows an association between ever having had a heart attack and currently using e-cigarettes, after controlling for smoking status. It is very possible (and quite likely) that many, if not most of the people with a history of myocardial infarction had experienced heart attacks years ago. And it is similarly likely that many of these heart attack victims had experienced the heart attack prior to starting to vape. In fact, it is likely that having a heart attack or a history of a heart attack was a stimulus that led the person to try vaping (because of the urgent need to quit smoking).

What the paper might actually be showing is simply that smokers who have experienced a heart attack are more motivated to try vaping to quit than smokers who have not had similar health problems. This makes complete sense and is certainly a plausible alternative explanation for the study findings.

Even the medical students who conducted the study do not conclude that vaping causes heart attacks. Appropriately, they merely conclude that they found a cross-sectional association and that further research is necessary before any conclusions can be drawn.

This is a great demonstration of what social scientists call "confirmation bias." When people have a pre-existing belief (i.e., vaping is terrible), they tend to interpret any scientific information in a way that reinforces their pre-existing beliefs (i.e., this study shows that vaping causes heart attacks). But science and scientific research is supposed to overcome this confirmation bias by establishing principles and procedures to promote objectivity.

Clearly, this is not happening with regards to the science of vaping. Now, vaping opponents have lost any semblance of scientific rigor and are willing to promote any research - even what essentially amounts to a science fair project - as supporting their pre-existing beliefs.

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