The Dogma of Evidence-based Medicine

byChristianKl1y25th Jan 201838 comments


In polite society it's currently fashionable to be in favor of Evidence-based Medicine and proclaim that we don't have enough of it. In this article I want to argue that this preference isn't backed up by good reasons. The paradigm of Evidence-based Medicine isn't backed up by evidence that proves the virtues of the paradigm but by faith.

What's Evidence-based Medicine in the first place? The term was defined in a scientific paper by Guyatt et al in their paper "Evidence-Based Medicine - A New Approach to Teaching the Practice of Medicine" in 1992. According to the paper Evidence-based medicine requires new skills of the physician, including efficient literature searching and the application of formal rules of evidence evaluating the clinical literature. Evidence-based Medicine was supposed to be about replace theory-based medicine with empirically-backed medicine.

They make the assumption that physicians who learn the skill of literature searching and applications of formal rules of evidence will produce better clinical results for their patients. Theoretically there are valid reasons why someone might believe in this assumption. For a community who sincerely beliefs in evidence-based thinking instead of practicing belief-in-belief I would however expect that they test their assumptions.

It would be possible to run a controlled study whereby some doctors get more classes on learning those efficient literature searching skills and the skills of application of formal rules of evidence. If the cost of that experiment would be too big, it would even be possible to seek correlation evidence. To my knowledge, nobody tried to run either study.

I opened a question on Skeptics.StackExchange to find out whether anybody could find studies who prove core assumptions of Evidence-Based Medicine and nobody replied with studies that validated the idea that teaching doctors more of those evidence based skills improves patient outcomes.

Brienne Yudkowsky wrote on Facebook that she thinks that the Hamming question for epistemic rationality might be "To which topics, or under what circumstances, do you apply different epistemic laws?". For many people medicine is such a field. The majority of supposed defenders of Evidence-based Medicine accept without evidence from controlled studies that those Evidence-based methods of practicing medicine are better. At the same time, they fight alternative medicine paradigms for not providing enough studies that back up their claims.

According to the core assumption in Evidence-based Medicine results that are found in one patient population generally generalize to other patients populations. If that would be true it should be easy to replicate studies. In reality replication often fails even when there's a lot of attention invested to get comparable patient populations.

In real world clinical settings the patient population is more diverse than the carefully chosen patient population of a trial. In the clinical trial patients often only take one drug and while in normal clinical practice patients often take multiple drugs to fight multiple diseases.

Another part of the core Evidence-based Medicine dogma is the dualistic notion that doctors should focus on creating clinical effects for their patients through proper intervention and not through placebo effects. This means that while patients don't care if they get better because of mind or matter, doctors are primarily focused on the matter. An alternative therapist who might get clinical effects for their patients by spending an hour talking to them get rejected in favor of a doctor who interviews a patient for 5 minutes and then gives them a pill. These dogmatic beliefs about how to think about the placebo effect are also largely formed without scientific investigation of the placebo effect. There's a strong double standard about what kinds of beliefs need studies to back them up and what can be accepted without empirical evidence because they make theoretic sense.

There's a belief that placebo blinding procedures generally result in patients not knowing whether or not the the patient got the placebo or verum. Rabkin et al investigated in their paper "How blind is blind?" how well patients can tell what they got. 78% of the patients and 87% of the doctors could correctly distinguish between placebo and verum when they were asked. A research community that would sincerely belief in the tenets of evidence-based medicine would start asking patients in every trial for their subjective belief of whether they got placebo. They behavior of the community we do have that keeps following their established rituals without questioning those rituals looks more like belief-in-belief.

One hypothesis is that patients know whether they take a placebo or verum because verum has side effects. In an environment where the placebo controlled effects of antidepressant as Kirsch et al described in their paper only makes on average 1.8 out of a 50 point scale, there's the question whether antidepressants with high side-effect unblind themselves and are thus better in direct comparison to antidepressants with less side effects. Unfortunately, the ethical review boards don't care about those issues and rather focus on preventing consent forms getting signed with pencils.

There's one Evidence-based Medicine belief that will look very strange to future students who want to make sense of our beliefs. It's the belief that the blind man sees better. The belief that it's bad to clearly see the object under investigation in all it's details. It's true that the practice of blinding can helps us from falling victim to various biases but having access to less data also prevents us from seeing real patterns. Ironically, this blindly leads to researchers not being interested in the subjective experience of their patients to the point that they don't gather data about whether the patients think that they got verum.

Why do we think we need Evidence-based Medicine in the first place? We don't want to trust in human authorities. We want science to free us of the need to trust authorities. Instead of asking us how we can develop justified trust in human authorities, we dream for objective knowledge that transcends human authorities.

I proposed in my post about Prediction-based Medicine a system in which we let doctors make predictions about the outcomes of their treatment and use the quality of those predictions to establish authority. Once we solve the problem of trust the knowledge production itself can get more diverse. One scientists might understand a disease better by doing phenomenological investigation of the subjective experience of patients. Another scientists might use a lot of sensors and run machining learning algorithms to better understand disease. Both profit if they don't have to fit inside the bureaucracy of Evidence-based Medicine and can focus on producing knowledge that helps doctors make better predictions about how to treat their patients.

It won't be as Hahnemann said "Wer heilt, hat Recht" ("He who cures is right") but "He who can predict in advance that he will cure the patient and then actually cures the patient is right".