Evidence-Based Medicine

In the comments, Bruce Charlton writes:

The failure to fund trials is combined with a suffocating dominance of the perspective of self-styled ‘evidence-based medicine’ (EBM) – including the groundless notion that only mega-trails should be taken seriously. . . Since the vast majority of randomized trials are industry funded, EBM has meant that industry has a de facto monopoly on ‘reputable’ therapeutic knowledge.

Delivering us into the hands of Big Pharma was not – of course – intended by the socialistic founders of EBM, but it has happened nonetheless.

This reminds me of something one of my students said. We were discussing male/female differences — in particular, the observation that women are more religious than men. One student said that in her experience, guys were either not religious at all or very religious.

I agree with her. I think this is why EBM has the form it does. Its male founders — not understanding the tendency that my student pointed out — went from one extreme (medical orthodoxy, unrelated to evidence) to another (evidence-based medicine). Reliance on evidence is a good idea, yes, but the founders of EBM couldn’t help making it resemble a religion. You might think that relying on evidence is the opposite of religion but they made the whole thing as religious as possible. EBM became just another way — just another excuse, really — to sneer at people.

Yes, Canker Sores Prevented (and Cured) by Omega-3

Here is a comment left on my earlier canker-sore post by a reader named Ted:

I found out quite by accident WALNUTS get rid of [canker sores] quite quickly. The first sign of an ulcer I chew walnuts and leave the paste in my mouth for a little while (30 seconds or so).

The first time was by accident, my ulcers disappeared so quickly I knew it had to be something I ate. And the only thing I had eaten differently the past day was walnuts.

Flaxseed oil and walnuts differ in lots of ways but both are high in omega-3. My gums got much better around the time I started taking flaxseed oil. I neither noticed nor expected this; my dentist pointed it out. Several others have told me the same thing. Tyler Cowen’s gums got dramatically better. One reader started and stopped and restarted flaxseed oil, making it blindingly clear that the gum improvement is caused by flaxseed oil. There is plenty of reason to think the human diet was once much higher in omega-3. All this together convinces me that omega-3 can both prevent and cure canker sores. Not only that, I’m also convinced that canker sores are a sign of omega-3 deficiency. You shouldn’t just get rid of them with walnuts; you should change your diet. Omega-3 has other benefits (better brain function, less inflammation, probably others).

Let’s say I’m right about this — canker sores really are prevented and cured by omega-3. Then there are several things to notice.

1. Web facilitation. It was made possible by the internet. My initial interest in flaxseed oil came from reading the Shangri-La Diet forums. I didn’t have to read a single book about the Aquatic Ape theory; I could learn enough online. Tyler Cowen’s experience was in his blog. Eric Vlemmix contacted me by email. No special website was involved.

2. Value of self-experimentation. My flaxseed oil self-experimentation played a big part, although it had nothing to do with mouth health. These experiments showed dramatic benefits — so large and fast that something in flaxseed oil, presumably omega-3, had to be a necessary nutrient. Because of these results, I blogged about omega-3 a lot, which is why Eric emailed me about his experience.

3. Unconventional evidence. All the evidence here, not just the self-experimentation, is what advocates of evidence-based medicine and other evidence snobs criticize. Much of it is anecdotal. Yet the evidence snobs have, in this case, nothing to show for their snobbery. They missed this conclusion completely. Nor do you need a double-blind study to verify/test this conclusion. If you have canker sores, you simply drink flaxseed oil or eat walnuts and see if they go away. Maybe this omnipresent evidence snobbery is . . . completely wrong? Maybe this has something to do with the stagnation in health research?

4. Lack of credentials. No one involved with this conclusion is a nutrition professor or dentist or medical doctor, as far as I know. Apparently you don’t need proper credentials to figure out important things about health. Of course, we’ve been here before: Jane Jacobs, Elaine Morgan.

5. Failure of “trusted” health websites. Health websites you might think you could trust missed this completely. The Mayo Clinic website lists 15 possible causes — none of them involving omega-3. (Some of them, we can now see, are correlates of canker sores, also caused by lack of omega-3.) If canker sores can be cured with walnuts, the Mayo list of treatments reads like a list of scurvy cures from the Middle Ages. The Harvard Medical School health website is even worse. “Keep in mind that up to half of all adults have experienced canker sores at least once,” it says. This is supposed to reassure you. Surely something this common couldn’t be a serious problem.

6. Failure of the healthcare establishment. Even worse, the entire healthcare establishment, with its vast resources, hasn’t managed to figure this out. Canker sores are not considered a major health problem, no, but, if I’m right, that too is a mistake. They are certainly common. If they indicate an important nutritional deficiency (too little omega-3), they become very important and their high prevalence is a major health problem.

Evidence Snobs

At a reunion of Reed College graduates who majored in psychology, I gave a talk about self-experimentation. One question was what I thought of Evidence-Based Medicine. I said the idea you could improve on anecdotes had merit, but that proponents of Evidence-Based Medicine have been evidence snobs (which derives from Alex Tabarrok’s credit snobs). I meant they’ve dismissed useful evidence because it didn’t reach some level of purity. Because health is important, I said, ignoring useful information, such as when coming up with nutritional recommendations, is really unfortunate.

Afterwards, four people mentioned “evidence snobs” to me. (Making it the most-mentioned thing I said.) They all liked it. Thanks, Alex.

Stoplights, Experimental Design, Evidence-Based Medicine, and the Downside of Correctness

The Freakonomics blog posted a letter from reader Jeffrey Mindich about an interesting traffic experiment in Taiwan. Timers were installed alongside red and green traffic lights:

At 187 intersections which had the timers installed, those that counted down the remaining time on green lights saw a doubling in the number of reported accidents . . . while those that counted down until a red light turned green saw a halving in . . . the number of reported accidents.

Great research! Unexpected results. Simple, easy-to-understand design. Large effects — to change something we care about (such as traffic accidents) by a factor of two in a new way is a great accomplishment. This reveals something important — I don’t know what — about what causes accidents. I expect it can be used to reduce accidents in other situations.

It’s another example (in addition to obstetrics) of what I was talking about in my twisted skepticism post — the downside of “correctness”. There’s no control group, no randomization (apparently), yet the results are very convincing (that adding the timers caused the changes in accidents). The evidence-based medicine movement says treatment decisions should be guided by results from controlled randomized trials, nothing less. This evidence would fail their test. Following their rules, you would say: “This is low-quality evidence. Controlled experiment needed.” The Taiwan evidence is obviously very useful — it could lead a vast worldwide decrease in traffic accidents — so there must be something wrong with their rules, which would delay or prevent taking this evidence as seriously as it deserves.

Twisted Skepticism (continued)

Writing about advances in obstetrics, Atul Gawande, like me, suggests there is a serious downside to being methodologically “correct”:

Ask most research physicians how a profession can advance, and they will talk about the model of “evidence-based medicine”—the idea that nothing ought to be introduced into practice unless it has been properly tested and proved effective by research centers, preferably through a double-blind, randomized controlled trial. But, in a 1978 ranking of medical specialties according to their use of hard evidence from randomized clinical trials, obstetrics came in last. Obstetricians did few randomized trials, and when they did they ignored the results. . . . Doctors in other fields have always looked down their masked noses on their obstetrical colleagues. Obstetricians used to have trouble attracting the top medical students to their specialty, and there seemed little science or sophistication to what they did. Yet almost nothing else in medicine has saved lives on the scale that obstetrics has. In obstetrics . . . if a strategy seemed worth trying doctors did not wait for research trials to tell them if it was all right. They just went ahead and tried it, then looked to see if results improved. Obstetrics went about improving the same way Toyota and General Electric did: on the fly, but always paying attention to the results and trying to better them. And it worked.

Is there a biological metaphor for this? A perfectly good method (say, randomized trials) is introduced into the population of medical research methods. Unfortunately for those in poor health, the new method becomes the tool of a dogmatic tendency, which uses it to reduce medical progress.