A recent study suggests that vaping may be linked to erectile dysfunction. The results are alarming if they're valid, though there are several critical reasons to doubt their validity.
A recent series of studies has linked electronic cigarette use (vaping) to a host of negative outcomes, including bone damage, stroke, cigarette smoking 'relapse', and depression—and that's just since September. These associations are very likely spurious for several reasons, as discussed in the links above, and it appears we have to add yet another negative consequence of vaping to this speculative list of maladies. According to a November paper published in the American Journal of Preventative Medicine, vaping may raise your risk of erectile dysfunction (ED):
"The use of ENDS [electronic nicotine delivery systems] seems to be associated with erectile dysfunction independent of age, cardiovascular disease, and other risk factors. While ENDS remain under evaluation for harm reduction and smoking-cessation potential, ENDS users should be informed about the possible association between ENDS use and erectile dysfunction."
The study involved 13,711 male participants age 20 or older who reported their experience with erectile dysfunction. Only 4.8 percent of these participants were current electronic cigarette users (vapers) and just over two percent reported vaping daily. Data for the paper came from the Population Assessment of Tobacco and Health (PATH) study, which we've discussed elsewhere. Current daily vapers were more than twice as likely to report ED compared to never-vapers.
The media, of course, played up the results. Outlets from CNN and Forbes to Insider and People ran copycat stories, but they all left out the most interesting and important details from the study. When we take those into consideration, the results look a lot less impressive than the headlines suggest.
Poor measures of vaping, smoking and ED
Study participants were classified as current someday ("i.e., not every day or occasional") or daily vapers, or smokers if they consumed cigarettes “every day or some days.” Beyond this self-reported information, the researchers didn't know how much or which e-liquids the vapers in their study used, nor did they know how many cigarettes each smoker consumed. This is a common problem in vaping research: e-cigarette use is defined so broadly that there's no way to establish a dose-response relationship between vaping and the health outcome in question.
Men were similarly classified as having ED based on a 1-item question: “Many men experience problems with sexual intercourse. How would you describe your ability to get and keep an erection adequate for satisfactory intercourse?” As a result, the study may have erroneously identified participants as having ED who actually don't or missed others with mild symptoms. The researchers summed up the problem with these data gaps towards the end of the paper, writing:
"... the analyses were based on both self-reported covariate data, ENDS use status, and ED status, all of which are subject to misclassification, recall, and social desirability bias ..."
Chicken or the egg: did vaping precede ED?
Another critical issue is that the study simply provided a snapshot of people who reported vaping and experiencing ED. There's nothing wrong with this cross-sectional study design; it can help answer a number of important questions, but it's not useful if you're trying to assess the long-term risks of a given exposure, vaping in this case. To highlight one potential issue, did the participants develop ED before they began vaping? If so, that means electronic cigarettes aren't to blame, though this study can't account for that possibility.
Confounding factors
On a related note, some other exposure besides vaping could have caused the participants' ED. The researchers adjusted their models for several common variables, but they still had blind spots. For example, many prescription drugs can cause or contribute to ED, but the study included no information about medication or drug use. Even something like alcohol, that highly addictive substance many of us consume without hesitation, has been linked to ED in previous studies. Pornography use, a favorite pastime of millions of American men, has also been posited as a cause of ED, particularly in younger age groups.
Did these or other factors contribute to the frequency of ED reported in the present study? I don't know, and neither do the researchers. That's the problem.
Here's another oddity buried deep in the paper:
Nevertheless, this study failed to detect an association between cigarette smoking and ED, also when accounting for current daily smoking versus nondaily smoking (data not shown).
Why would vapers and dual users of vapes and cigarettes face a higher risk of erectile dysfunction than smokers? They both consume nicotine, which the researchers suggested as the most plausible cause of ED. They speculated that some cigarette smokers may have refused to respond to the ED question because they suffer from ED, or they could have been “light smokers overall.” That's certainly possible, but, again, this is all guesswork.
In fairness, the authors didn't claim that vaping causes ED, only that there appears to be an association between the two. They were also careful to acknowledge some of the limitations we've discussed. Vaping certainly could carry some so-far undiscovered side effects; we should remain open to that possibility as new evidence comes in. But if vaping plays any role in the development of sexual dysfunction in men, studies of this caliber won't tell us anything useful.
