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An Interview with Distinguished University Professor Gordon Guyatt, OC, FRSC on 2019 EBM, and Science-Based Medicine and Evidence-Based Medicine (Part Four)


Author(s): Scott Douglas Jacobsen

Publication (Outlet/Website): In-Sight: Independent Interview-Based Journal

Publication Date (yyyy/mm/dd): 2019/12/08


Dr. Gordon Guyatt, OC, FRSC is a Distinguished University Professor is the Department of Health Research Methods, Evidence, and Impact at McMaster University. He is a Fellow of the Canadian Academy of Health Sciences. The British Medical Journal or BMJ had a list of 117 nominees in 2010 for the Lifetime Achievement Award. Guyatt was short-listed and came in second place in the end. He earned the title of an Officer of the Order of Canada based on contributions from evidence-based medicine and its teaching. He was elected a Fellow of the Royal Society of Canada in 2012 and a Member of the Canadian Medical Hall of Fame in 2015. For those with an interest in standardized metrics or academic rankings, he is the 15th most cited academic in the world in terms of H-Index at 245 and has a total citation count of more than 261,883 (at the time of publication). That is, he has among the highest H-Indexes or the highest H-Index, likely, of any Canadian academic living or dead. He discusses: developments of EBM throughout 2019; and EBM versus SBM.

Keywords: Canada, evidence-based medicine, Gordon Guyatt, McMaster University, medicine, science-based medicine.

An Interview with Distinguished University Professor Gordon Guyatt, OC, FRSC on 2019 EBM, and Science-Based Medicine and Evidence-Based Medicine: Distinguished Professor, Health Research Methods, Evidence, and Impact, McMaster University; Co-Founder, Evidence-Based Medicine (Part Four)[1],[2]

*Please see the footnotes, bibliography, and citation style listing after the interview.*

1. Scott Douglas Jacobsen: What are some new developments in EBM? We have talked about those before. We can reference those. Let’s range from January 1, 2019 to the present. Your own repertoire of research.

Distinguished Professor Gordan Guyatt: I can talk about research known to me. One guy doing the most dramatic is working in perioperative medicine named P.J. Devereaux. He is a leading person in cardiology, particularly related to perioperative medicine. What he has found is that a lot of the people who we didn’t recognize before having the equivalent of heart attacks when they are undergoing surgery. We didn’t know about it. Because when they were under surgery, they are under narcotics and painkillers, and sedation.

So, when they are having heart attacks and nobody notices, what he started to do was to routinely measure their – more and more sophisticated ways to – enzymes released from the heart when the heart is damaged, he measured them in higher-risk people. He did this routinely. He found 80% of the heart attacks occurring when people are undergoing surgery are never noticed. If you do not do this routine monitoring, so, that was a big deal. So, subsequently, he did a randomized trial.

Where he was taking people with these heart attacks and giving them anti-coagulants after the surgery or not, the standard, at the time, was to not give them anti-coagulants. He found that major cardiovascular events, subsequent heart attacks, were reduced by the anti-coagulants. It was a major change in how we monitor people. First of all, we are, now, monitoring troponins.

We never did this before in the research. We are finding all of these heart attacks. We are treating all these heart attacks that they, typically, were untreated before. Now, they would be treated with standard medications like aspirin and statins. Drugs to lower blood lipids and anti-coagulants. That is going to be a major worldwide change in practice.

First of all, monitoring the enzymes to detect the heart attacks, which we didn’t notice before, and then treating them, it is reduce subsequent events. That has been one major change, which will have a big worldwide impact. Based on the furtherance of P.J. Devereaux’s research, what will be some next steps? One of the next steps is that we were also finding that people were having small strokes.

We never noticed them before. Now, we have ways of imaging the brain, sophisticated imaging, to find small strokes that people did not notice. Now, we have found that the people who are having strokes; if you follow them for a year, they are having cognitive deterioration, which does not happen to others who do not have the strokes.

Further work will be done. The preliminary work will establish that this is going on, then the question will be, “Is there anything that we can do to prevent the strokes?” That is another aspect. The other major thing that he is doing is that he has found things. It all started with 40,000 people worldwide and following them through surgery and seeing what happens.

A lot of them run into trouble of one sort or another. The strokes being one thing, infections being another, various complications. His idea: he uses the idea of anesthesia. Anesthesia, when it got started in the 1850s, people would die because of the anesthesia, complications of the anesthesia. Gradually, we developed more and more sophisticated monitoring through surgery.

Now, deaths from anesthesia have been reduced, literally, 100-fold. They basically never happen, almost never happen. The reason is that there is an anesthesiologist. They not only have the surgeon, but they have the anesthesiologist by the bedside through surgery monitoring everything that is going on and making very quick adjustments if there are any problems.

The very careful monitoring with an expert physician trained to do just that, monitor people through surgery. It has basically eliminated the complications associated with anesthesia. P.J. says, ‘We monitor people.” No one wants to travel for their surgery. They to travel as soon as they go back to the ward after their surgery and the subsequent days.

He says, very reasonably, “That’s because we stopped monitoring them.” Nurses come by every few hours. They check something, and so on. Now, we have technology that can monitor continuously. So, they monitor the oxygen saturation, the heart rate, the blood pressure. When we are doing this in studies, we are finding people running into trouble. Nobody notices for a few hours.

So then, the question is, “If we monitor closely electronically without nurses checking, the nurses can sit at the nurses’ station and look at the monitors and say, ‘Look! Something is happening.” Go down and get the doctor involved and have them act much more quickly, we think this can further lower or have real potential for nipping the problem in the bud – to use that metaphor.

He also found out that a third of the deaths that happened after surgery happened in the first thirty days after people go home. People are discharged. Things look okay. They run into trouble when they go home. That is a major problem. What is the solution to that? Monitor them once they get home! Once they run into trouble, then you bring them back, this monitoring and quick response could – he says or wants – to cut the mortality in half.

He is an ambitious guy [Laughing].

Jacobsen: [Laughing].

Guyatt: So far, everything, all his leads, he has done has worked out. It kind of makes sense. The metaphor or analogy as to what happens with anesthesia and close monitoring. We eliminated bad things happening. As soon as we stop monitoring, bad things start happening. It, certainly, has huge potential.

2. Jacobsen: I want to dip a little bit into, in fact, a few news articles, actually, around red meat.

Guyatt: Yes, a lot of excitement about red meat [Laughing].

Jacobsen: In popular Canadian culture, there is so much fun people are having with it. I am told. And if you don’t want to be told, you will be told anyways. There are a lot of keto diets, red meat diets, and all-meat diets. All these phrases people are, basically, making up on the fly in the last year, or two, or three.

One, as a cultural comment, what do you think is the source of it? And two, what is the strongest evidence for and against this kind of dietary recommendation to people? Also, just compared to ordinary red meat intake, for example.

Guyatt: My impression is that the particular diets have been around and the enthusiasm for particular diets has been around a lot longer than a couple of years. Perhaps, people are talking about them more or, maybe, they’re getting a little stranger than they used to be. Certainly, in terms of weight loss, all the weight loss diets; we call them “Branded Diets.” Atkins Diet, so on and so forth, people have made a lot of money telling people, “This is the way to lose weight.” They have been around for a long time.

None of them are terribly successful in helping people lose weight over the long term. Although, they are well-advertised. But it is true that you have paleolithic diets, keto diets, and God knows what else. Fasting, as far as I understand it, is popular now. One might describe these as fads. The evidence supporting any of them is more or less absent.

Jacobsen: [Laughing] thank you. Also, with regards to comparing methodologies, EBM has been around since ’91, the older version…

Guyatt: …The term EBM has been around since ’91.

Jacobsen: Then values and preferences as an adjunct were much later.

Guyatt: That’s right.

3. Jacobsen: Speaking of the more modern forms of EBM and speaking of Science-Based Medicine, I am sure that you’ve read the literature and are aware of the critiques that have come your way. What are your thoughts on Science-Based Medicine (SBM)?

Guyatt: Maybe, you are monitoring the literature closer than I am. I have never heard the phrase Science-Based Medicine. As a historical note, when we were first developing the notion of what became EBM, my first idea of what to call it was Scientific Medicine. At the time, I was the Director of the Residency program in Internal Medicine at McMaster University. I presented this idea to my colleagues.

The basic scientists were completely enraged. They thought that they were the real scientists, not clinical epidemiologists like me. They were so angry. I said, ‘I have to come up with a different name than Scientific Medicine.’ The alternative was EBM, which turned out to be much more successful.

Jacobsen: Their emphasis in SBM is science in general rather than evidence in particular. It was proposed by “Yale neurologist Dr. Steven Novella… and surgical oncologist Dr. David Gorski (Karmanos Cancer Institute) in early 2008” (Ingraham, 2014):

EBM is a vital and positive influence on the practice of medicine, but it has its limitations. Most relevant to this blog is the focus on evidence to the exclusion of scientific plausibility. The focus on evidence has its utility, but fails to properly deal with medical modalities that lie outside the scientific paradigm, or for which the scientific plausibility ranges from very little to nonexistent. (Ibid.)

Guyatt: What are they saying? Are they implying that we should pay more attention to things like homeopathy? Or are they saying that we should pay less attention to homeopathy? From what you’ve read, I’m not sure which.

Jacobsen: Based on their orientation, there would be more emphasis on homeopathy in terms of critique. That tends to be the orientation.

Guyatt: That we shouldn’t take homeopathy too seriously. Is that the point?

Jacobsen: I think so.

Guyatt: Okay, I don’t see any EBM people advocating for homeopathy as far as I know.

Jacobsen: There you go. Further quote:

EBM, although a step forward over prior dogma-based medical models, ultimately falls short of making medicine as effective as it can be. As currently practiced, EBM appears to worship clinical trial evidence above all else and nearly completely ignores basic science considerations, relegating them to the lowest form of evidence, lower than even small case series. This blind spot has directly contributed to the infiltration of quackery into academic medicine and so-called EBM … (Ibid.)

Guyatt: This seems silly to me because they seem to, on the one hand, to be claiming that we should be paying more attention to what goes on in the laboratory. But we know that much of what goes on the laboratory or seems promising in the laboratory when tested in clinical practices turn out to be, certainly, not successful in the way one hopes.

Not infrequently, it is harmful in the way that one does not hope. In terms of quackery, if one sets standards for insisting on randomized trials, it ends quackery because when tested in randomized trials: things that don’t work, don’t work! So, people cannot claim that they work.

So, that seems silly. The part that you read to me is legitimate. It is the somewhat simplistic hierarchy of evidence that was initially proposed, which changed in 2004 with the first publication in the British Medical Journal in what we called the GRADE approach to assess the quality of evidence.

It said, “Randomized trials may start as high-quality evidence. But there are five categories of problems that  may lower evidence for randomized trials.” Those were the risk of bias, randomized trials not being conducted optimally, inconsistent results from one trial to another, small trials with imprecise results, and indirectness of evidence.

Where, for instance, a lot of my patients are over 90 now. Randomized trials were all done in younger people. Can you apply those with the same confidence to people over 90? Probably not. There is a new and more sophisticated understanding of evidence in randomized trials. It also recognized that infrequently, but perhaps not that infrequently, evidence from what we call observational or non-randomized studies can be high-quality evidence.

We have a considerable list of such things including hip replacements, epinephrine for anaphylactic shock, or insulin for diabetic ketoacidosis, dialysis for renal failure, and they go on. These things, appropriately, have never been tried in randomized trials because their results are so large and dramatic. So, you don’t need randomized trials to show that they are effective.

The new and more sophisticated hierarchy of evidence, first of all, acknowledges limitations in randomized trials and, secondly, recognized situations when evidence from non-randomized studies can, nevertheless, end up as high-quality evidence leading to strong inferences. That is another way, I would say, that they are not recognizing the sophistication that has been around in EBM since 2004.

Jacobsen: One thing, did you want to close on a note of the progress of science?

Guyatt: So, here I am. On Tuesday, or seven days ago, I started to notice that my balance wasn’t what it should be. In the next 24 hours, by Wednesday afternoon, it was getting to be a real problem, when I was falling to the left.

Ironically, it so happened that the residency program, which I still help out in, has an EBM day. Where they bring all the residents together to learn EBM stuff, this was on the EBM stuff. They, usually, highlight my teaching on the EBM day.

I, usually, lecture to the whole group. They break into small groups. By the end of the day, they knew; I was in trouble. They said, “You’ve got to do something quick Dr. Guyatt.” They were nice to me. One accompanied me to down the general and bought me an Uber.

They came with me. We found a neurologist. They all just thought I was having a stroke. They brought me to have a CT scan. The new CT scan at the general. I was pretty impressed. It felt like it took two minutes or less to do the CT scan.

It used to be a big production sitting there for half an hour. I didn’t know I was in the machine. They said, “No! You do not have a stroke. You are having a subdural hematoma. This blood collecting around the brain and squeezing your brain. That’s what is going on.”

Within an hour of that, they didn’t even take me to the proper operating room. They didn’t need to. They took me to a procedure room, put a drain in. By the next morning, I was fine!

Pretty impressive modern medicine, I would say.

Jacobsen: Thank you.


Ingraham, P. (2014, August 26). Why “Science”-Based Instead of “Evidence”-Based?: The rationale for making medicine more science-based. Retrieved from

Appendix I: Footnotes

[1] Distinguished Professor, Health Research Methods, Evidence, and Impact, McMaster University; Co-Founder, Evidence-Based Medicine.

[2] Individual Publication Date: December 8, 2019:; Full Issue Publication Date: January 1, 2020:


In-Sight Publishing by Scott Douglas Jacobsen is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. Based on a work at


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