Reblogged:Causation? Which Way? Is There Any?

[Gus Van Horn blog]

Just about anyone who has ever heard a physician discuss the use of cotton swabs to remove earwax will have heard that the practice can cause Bad Things to happen. ("Q-tips can push wax further into the ear canal, which can cause impaction, discomfort, or a rupture in the ear drum....") Some people follow this advice and others ignore it. I have lived in both camps, but will leave it at that for now.

But I have never reviewed the literature on the subject, and that's where a writer known as the Resident Contrarian comes in. The Resident Contrarian admits up front that he is a layman and asks that you not rely on him for medical advice. Fair enough, but he asks some good questions and makes some solid points.

My favorite comes from his consideration of a very commonly-cited study:

Image by Alexander Grey, via Unsplash, license.

[K]ids whose ears were cleaned by cotton tipped swabs were three to four times as likely to have plugs, and that effect is strong enough that we can at least to some extent disregard the small sample size.

But an obvious objection springs to mind - what if causation swings the other way? If the mothers in this survey were more likely to use cotton tipped swabs on kids who had hyper-active earwax production, then the study authors could have their correlation/causation flipped. To their credit, they acknowledge this before saying something seemingly irrational... [bold]

If the Resident Contrarian has indeed performed a thorough literature review, we have an example of conventional medical wisdom that may be complete bunk. Nonetheless, it's easy to see how such a state of affairs could have arisen: Earwax is not that important in the grand scheme of things, is hard to study, or both -- and erring on the side of caution is a common enough practice.

If you're going to pick between too much earwax and damage to the inner ear, you'll probably take the wax -- every day of the week and twice on Sundays if you're choosing on behalf of someone else.

A possible case in point: When I was young, I had heard this advice and followed it for some time. A doctor eventually surprised me during a routine checkup by asking me if I used Q-Tips, as I had lots of wax buildup. He was mildly surprised by my negative answer, then performed a procedure to remove the wax.

It was a couple of days before I became acclimated to how much better my hearing became, and I decided to start using cotton swabs to keep things that way. I have been using them ever since.

In the process of making that decision, I reconsidered the advice and immediately wondered How are the swabs pushing wax into the ear? Who holds them down on the way into the ear? Do people ever push inward when applying pressure?

I realized that while there was advice, that advice didn't work for me, and there was no sensible mechanical explanation for how the bad result was supposed to come about.

So, while anecdotes are not data, my experience comports with the idea that this bit of medical advice is questionable.

-- CAV

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