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.