Vaping and heart attacks

Junk science veteran Stanton Glantz is excited about a study that purports to show that vaping causes heart attacks (myocardial infarction). The study was published in November last year but appeared in the obscure, low status (and possibly predatory) journal Cureus and, thankfully, the media never picked it up.

The author, Talal Alzahrani, had previously produced a widely criticised study claiming that e-cigarette use is associated with heart attacks which included dual users of vapes and cigarettes and therefore could not isolate the effect of smoking from the putative effect of vaping. Glantz was a co-author. Glantz himself has had a study claiming that vaping causes heart attacks retracted. The new study, written by Alzahrani alone, seeks to avoid the earlier problem by looking only at vapers who say that they have never smoked. 

As Glantz says on his blog:

 

To get enough adult e-cigarette users who never smoked, Alzahrani combined data from the US National Health Interview Surveys from 2014 through 2021, which yielded 1237 never smoking e-cigarette users.  After controlling for other risk factors for heart attack, he found that current e-cigarette users had 2.6 times the odds of having had a heart attack as non-e-cigarette users (95% CI 1.44-4.77) compared with never smokers who did not use e-cigarettes.

 

This is not far off the risk associated with smoking and is highly implausible from the outset since vapes do not contain many of the substances in cigarettes that are known to cause heart disease. The most suspicious thing about the study is that it does not show how many heart attacks occurred among the vaping and non-vaping groups. All we are given are the adjusted relative risks.

And there must have been some huge adjustments because everything about the vaping group implies that they would suffer fewer heart attacks.

 

A total of 139,697 subjects were never users, and 1,237 subjects were current e-cigarette users. The data analysis showed that current e-cigarette users were significantly younger than never users. E-cigarette users were less likely to be female (40% vs. 60%, p <0.01), or have diabetes (3% vs. 10%, p <0.01), have hypertension (11% vs. 32%, p <0.01), hypercholesterolemia (8% vs. 27%, p <0.01), have or be overweight or obese (56% vs. 65%, p <0.01) compared to never users.

 

The average age of the vapers was 28 whereas the average age of the control group was 50. Heart attacks are very rare among young people and there were only 1,237 never-smoking vapers to study. If you can find the data from the US National Health Interview Surveys, you may be able to confirm or deny, but I would bet the following:

Firstly, that there were a tiny number of heart attacks among the never-smoking vapers. I would be very surprised if there were more than ten.

Secondly, that a larger proportion of the controls had a heart attack than the never-smoking vapers.

Thirdly, that the claimed association between vaping and heart attacks is purely the result of adjustments made to the data that defy logic.

Why else would he not show the unadjusted figures? Why else would he not submit his study - which, if its findings were true, is incredibly important - to a decent journal?  

Nullius in verba.