William Cayley: Evidence based medicine—are we really there yet?

bill_cayley_2People almost invariably arrive at their beliefs not on the basis of proof, but on the basis of what they find attractive.” Blaise Pascal

Can we make evidence based medicine work if we don’t understand the evidence?

I appreciated this week’s BMJ analysis piece by Margaret McCartney et al, which gave recommendations for ways to make “evidence based medicine work for individual patients” (more specifically, how to make evidence based guidelines work for individuals). And if you’d like a more humorous, and musical, version of the same message, take a look at James McCormack’s recent video:

Whether you prefer the written analysis or the musical video, they both make clear the point that there needs to be more emphasis on shared discussion in the application of evidence to individual patient life situations, and much less emphasis on unilaterally directing this or that course of action.

However, when discussing recent, well researched, and “well evidenced” guidelines, I’ve been startled to hear people (who I think would espouse support of EBM) criticize the guidelines for their conclusions, without engaging in a discussion of their evidence base. Two cases in point: the 2013 American College of Cardiology/American Heart Association guideline on the treatment of blood cholesterol and the 2016 US Preventive Services Task Force guideline on aspirin use to prevent cardiovascular disease and colorectal cancer.

Both guidelines have good evidence reviews, and both have (I think) appropriate discussions of shared decisions. They may not be perfect, but they seem to be about the best we can get to, given the fact that all knowledge is limited, clinical science is ever evolving, and we simply cannot find clear answers to all clinical questions. Nevertheless, I’ve been startled to run into more than a few clinicians who take issue with these guidelines’ conclusions, without engaging in a discussion of the evidence.

In Mortimer Adler’s classic How to Read a Book, he argues that “To disagree without understanding is impudent.” While I’m not sure I’d choose the word “impudent” in my discussion of evidence based medicine, Adler makes a salient point. To disagree with conclusions, without engaging with the underlying reasoning, is taking an invalid intellectual shortcut.

Granted, evidence based medicine is a complex and ever evolving approach to understanding medical knowledge. Granted, there are manifold problems with evidence based medicine as an intellectual enterprise (evidence that is important but unpublished, “hijacking” of the term “evidence” for all sorts of information that isn’t really evidence, problems with trial reporting, etc).

Nevertheless, if we are to espouse (and teach and practice) truly evidence based medicine, our discussions with each other and with our patients need to be first and foremost about the evidence, and then secondarily about the policies and recommendations.

Whether with a colleague or a patient, to leap directly to recommendations without engaging with the evidence constitutes an intellectual shortcut that betrays the first principles of evidence based medicine.

William E Cayley Jr practices at the Augusta Family Medicine Clinic; teaches at the Eau Claire Family Medicine Residency; and is a professor at the University of Wisconsin, Department of Family Medicine.

Competing interests: I declare that I have read and understood BMJ policy on declaration of interests and I have no relevant interests to declare.