The search for “evidence-based” guidelines

Fake Newspaper on Kitchen Table


The term gets thrown around like it is the end-all and be-all seal of authority. When we hear something is evidence-based, it instills a sense of accuracy, truth, and reliability. But is that justified?

As we have mentioned before, not all evidence is of equal quality. Therefore, we need to know more than whether something is based on evidence. We need to know the quality of evidence on which recommendations are based.

A recent article in JAMA highlighted the unfortunate disconnect between the promotion of evidence-based guidelines and the quality of the underlying evidence.

JAMA: Levels of evidence supporting American College of Cardiology/American Heart Association and European Society of Cardiology guidelines, 2008-2018

The authors started with a simple question:

What proportion of recommendations in current American College of Cardiology/American Heart Association (ACC/AHA) and European Society of Cardiology (ESC) guidelines are supported by evidence from multiple randomized controlled trials (RCTs), and how has this changed over the past 10 years?

It certainly seems like a reasonable question. Given the strength with which the ACC, AHA and ESC stress their guidelines on nutrition, cholesterol, statins and other topics, and how they openly criticize those who promote different viewpoints, we should expect the level of evidence supporting official guidelines to be exemplary.

Unfortunately, the JAMA study concluded what many in the “skeptical” world suspected. Only 8.5% of the recommendations from the ACC/AHA and 14% from the ESC were based on level A evidence (randomized control trials), with 41% and 54% coming from the lowest level, level C evidence (expert opinion only). What’s worse, these numbers have not improved at all in current guidelines when compared to the prior version, and in fact, quality of evidence may have decreased.

These medical associations are supposed to be the most trustworthy organizations in medicine, promoting the highest quality recommendations for guiding doctors and patients alike in their quest to promote health.

We find this troubling. We strive to match our recommendations with the level of evidence, and that is why we created guides to evidence ranking, and why we specify the strength of evidence behind our claims. We believe any influential group has the same responsibility to the public.

Hopefully studies like the one from JAMA will continue to highlight the all-too-common disconnect between the strength of recommendations and the strength of evidence. We all have our opinions and biases, but those have no place in official guidelines. We have to admit there is much that we do not know and make sure we are clear in differentiating evidence-based practice and opinion-based theory.

Regardless of the controversy — Are whole grains healthy?Is saturated fat dangerous?Should we all be on statins?Is cholesterol really a primary concern for us all? — we need to equalize strength of evidence with strength of recommendations. That is a big part of our mission.

Stay tuned for more evidence-based guides to help you on your path to health.

Thanks for reading,
Bret Scher, MD FACC


The Diet Doctor policy for evidence-based guides

Guide Our evidence-based guides are based on the currently best available scientific evidence. There are in-line references supporting each key statement or recommendations about diagnosis, treatment or prognosis.


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