EBM vs Experience

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These are two basic methods of handling knowledge in medicine. Let's take them one by one.

Experience Based Medicine

If I have treated 30 patients a certain way and almost always had a good result, I'm inclined to treat any following patients the same way, until my luck changes. This is called "experience based medicine". It is in no way based on pure luck, since that wouldn't work. It is based on theoretical knowledge of pathophysiology coupled with real-life experience and it usually works fairly well. The problem is that you never know exactly why you have good results or if the same treatment would be valid in the hands of other physicians having another group of patients. You don't know if your own person has anything to do with it, or if you happen to live in an area where the patients react a certain way. Or possibly if your therapy only works because most of your patients are on another therapy of yours that is uncommon in other areas. Or maybe your patients are mostly related and have a common gene setup. Or... or...

Evidence Based Medicine

The best way to find out if a certain therapy works or not is to compensate for all the known and unknown variations I mentioned in the previous section. You can do that by selecting the patients you test on entirely randomly, so there's little chance there are factors in common among them, such as family traits, environmental factors in a certain neighborhood, etc. A "randomized" trial does just that. It's even better if the experience and bias of the doctor could be neutralized, and you can do that by not telling the doctor if he is treating the patient with the real thing or just placebo. Naturally, the patient doesn't know either, so there's two of them that are kept in the dark, which is why this method is called "double blind". Finally, you compare the outcome of the therapy with the outcome in the group that didn't get the therapy, which forms the control group. And this feature is called "controlled". Now, all together, say after me: "Randomized, controlled, double-blind study of... something", but don't say "Randomized, controlled, double-blind study of nifedipine in anesthetized dogs undergoing cardiac bypass" as one of my collegues once upon a time wrote... Can't be double-blind, since the dogs don't understand what's going on and are under anesthesia anyway. We laughed so hard he changed it. Or maybe it can, can it?

Which one should it be?

We know from experience that experience based medicine is not very effective. We make as many incorrect deductions from experience as we make correct deductions, and on the whole we don't progress much working that way. I think we even proved it using evidence based methods, even though the double-blind part may be hard to achieve.

Since we decided that evidence based medicine (EBM) is the only true religion for us, we have to have methods of dissipating the knowledge that is created this way. Remember, if you advance your knowledge by experience, you need nobody else to tell you, you experienced the knowledge first hand. But if you rely on EBM, you have to let someone else tell you about new discoveries, because there is by definition no way you could find out entirely on your own. You have to either read voraciously, go to seminars very often, or have some method of finding the information as you go along and find yourself in situations where you need to find out what the current state of the knowledge in a certain area is.

The standard way of keeping abreast of medical science has always been journals and symposia. Both these methods are best suited to the old experience based knowledge building, since journals and symposia only lay the groundwork for the knowledge that you would then gather during your daily work.

EBM is another beast, entirely. There is no synch between new discoveries and your need of knowing about them. You may go to a symposium and learn 20 new things out of 2,500 new things that have been discovered since the last time you went to a symposium. Exactly which 20 of those 2,500 things happen to be presented at that symposium is almost entirely up to chance. And which of the 20 things you learned actually become applicable to the random selection of patients you will see between the symposium and to that point in time when you forgot about these 20 new things, is also a totally random selection. The one thing this method guarantees is that you will not have learned the absolut majority of new discoveries that could have helped your patients, if you rely only on this method of knowledge distribution.

Another, much more promising, method is to check up on the current state of knowledge in every area relevant to the treatment or diagnosis of every patient you see. You have to check up on that knowledge, even if you are sure you know everything there is to know about it, because you can't be sure the state of knowledge hasn't changed recently. There are a number of tools available to do this, mostly web based collections of clinical guidelines. But there are two problems with this. The first is that these collections are rarely adapted to this way of working and usually come as a collection of literary works, i.e. PDF files of 50, 100 or even more pages. It's impossible to read through anything like that while the patient sits next to you waiting for your wise words. Makes you look like a total loser.

The other problem is that most doctors don't have the instinct to go look things up while actually doing clinical work. Traditionally, we sat down a couple of hours a week to study up on things from textbooks, but that won't help in the scenarios I'm describing here. If you read up on asthma therapy last summer, having spent half a day at it, you're probably not going to repeat that for a couple of years, so any new developments in asthma therapy will pass you by entirely unnoticed unless you check it up every time you see an asthma patient.

Finally, even if we as doctors are up to date and have been exposed to the latest knowledge of the pathologies we need to know, we tend to forget details, often important details. We need a checklist, just like the airplane pilots use, to remind us of the finer points of diagnosis and therapy.

Where do we go from here and why?

Why am I so incensed about this? Because I'm absolutely convinced that there is no greater source of suffering and expenses than the lack of immediacy in learning about new discoveries in diagnosis and treatments, and the lack of the checklist I mentioned in the previous section. When we flounder in diagnosis or treatment, it is very often due to forgetting about an alternative diagnosis or test we used to know about, or a treatment step we have actually learned. A simple short reminder of the most important elements in diagnosis and treatment of a disease would be immensely valuable, if it was available at the tip of your fingers at the right moment.

As you may have inferred by now, this is one of the major roles of the clinical guidelines that constitute the template for an "issue". That is why it is there.