Recently, while debating a respected colleague regarding a shift in practice towards treatment X, despite a lack of evidence showing its superiority, my colleague said: “But we know that practice always runs ahead of the evidence”. He was implying that the evidence would one day catch up and justify the practice. I wondered if medical practice really was running ahead of the evidence, or whether it was running away from it.
When clinical practice does run away from the evidence, we tend to spend our time gathering evidence to support the current practice, instead of using an objective evaluation of the current evidence to inform future practice. This is known as putting the cart before the horse. It is also known as Confirmation Bias.
Like the ghosts in The Sixth Sense, many clinicians and researchers only see what they want to see. I am not referring to a conscious process, where a deliberately biased argument is created (case-building) such as in a debate. In medical practice it is usually subconscious, where the selection of patients, measurement tools, outcomes and time-points tends to favour the beliefs of the researcher, and the researcher’s biases are then confirmed.
Even if the evidence is not clearly supportive, some may interpret the results as confirming their pre-conceived beliefs. This is also confirmation bias.
Confirmation bias is seeking, interpreting or recalling evidence in a way that is favourable to existing beliefs, expectations or hypotheses. And it is one of the most problematic aspects of human reasoning.
The bottom line
Many clinicians are running their practice on confirmation bias, or less. I think trends (read: fashions) in current practice should slow down and wait until the evidence catches up. The two can then travel together, preferably with the evidence doing the driving.
For a very long and boring paper on confirmation bias, read this article.