SGEM Xtra: EBM Master Class – McGill University Grand Rounds 2020

Date: January 4th, 2021 This is an SGEM Xtra episode. I had the honour of presenting at the McGill University Emergency Medicine Academic Grand rounds. They titled the talk "Evidence-Based Medicine Master Class". The presentation is available to watch on YouTube, listen to on iTunes and all the slides can be downloaded (McGill 2020 Part 1 and McGill 2020 Part 2). Five Objectives: Look at the burden of proof and talk about what is science Discuss EBM and give a five step process of critical appraisal Talk about biases and logical fallacies Do a check list for randomized control trials Record a live episode of the SGEM 1) Who has the Burden of Proof and What is Science? Those making the claim have the burden of proof. It is called a burden because it hard - not because it is easy. We start with the null hypothesis (no superiority). Evidence is presented to convince us to reject the null and accept there is superiority to their claim. If the evidence is convincing we should reject the null. If the evidence is not convincing we need to accept the null hypothesis. It is a logical fallacy to shift the burden of proof onto those who say they do not accept the claim. They do not have to prove something wrong but rather not be convinced that the claim is valid/“true” and this is an important distinction in epistemology. What is science? It is the most reliable method for exploring the natural world. There are a number of qualities of science: Iterative, falsifiable, self-correcting and proportional. What science isn’t is “certain”. We can have confidence around a point estimate of an observed effect size and our confidence should be in part proportional to the strength of the evidence. Science also does not make “truth” claims. Scientists do make mistakes, are flawed and susceptible to cognitive biases. Physicians took on the image of a scientist by co-opting the white coat. Traditionally, scientists wore beige and physicians wore black to signify the somber nature of their work (like the clergy). Then came along the germ theory of disease and other scientific knowledge. It was the Flexner Report in 1910 that fundamentally changed medical education and improved standards. You could get a medical degree in only one year before the Flexner Report. The white coat was now a symbol of scientific rigour separating physicians from “snake oil salesman”. Many medical schools still have white coat ceremonies. However, only 1 in 8 physicians still report wearing a white lab coat today (Globe and Mail). Science is usually iterative. Sometimes science takes giants leaps forward, but usually it takes baby steps. You probably have heard the phrase "standing on the shoulders of giants"? In Greek mythology, the blind giant Orion carried his servant Cedalion on his shoulders to act as the giant's eyes. The more familiar expression is attributed to Sir Isaac Newton, "If I have seen further it is by standing on the shoulders of Giants.” It has been suggested that Newton may have been throwing shade at Robert Hooke. Hooke was the first head of the Royal Society in England. Hooke was described as being a small man and not very attractive. The rivalry between Newton and Hooke is well documented. The comments about seeing farther because of being on the shoulders of giants was thought to be a dig at Hooke's short stature. However, this seems to be gossip and has not been proven. Science is also falsifiable. If it is not falsifiable it is outside the realm/dominion of science. This philosophy of science was put forth by Karl Popper in 1934. A great example of falsifiability was the claim that all swans are white. All it takes is one black swan to falsify the claim. There are some philosophers that refute Popper's claim about falsifiability.  Science is self-correcting. Because science is iterative and falsifiable it is also self correcting. Science gets updated.