Common biases can cause major physician errors

It’s tempting to believe that physicians are logical, meticulous thinkers who perfectly weigh the pros and cons of treatment options, acting as unbiased surrogates for their patients. In reality, this is often far from the case. Bias, which takes many forms, affects how doctors think and the treatment decisions they make.

Racial biases in treatment decisions by physicians are well documented. One study found that black patients were significantly less likely than white patients to receive pain medication in the emergency department, despite reporting similar levels of pain. Other research suggests that longstanding racial biases among providers might have contributed to racial differences in patient trust in the health system. But a growing body of scientific research on physician decision-making shows that doctors exhibit other biases as well — cognitive ones — that influence the way they think and treat patients. These biases lead doctors to make the same mistakes as the rest of us, but usually at a greater cost.

Cognitive biases refer to a range of systematic errors in human decision-making stemming from the tendency to use mental shortcuts.

Prominent examples include confirmation bias, the tendency to interpret new information in a way favourable to one’s preconceptions; and anchoring, the tendency to overly weight an initial piece of information, even when order does not matter. Anchoring helps explain why if you see a car priced at $20,000 and a second car priced at $8,000, you might conclude the second car is cheap, whereas if the first car cost $3,000 you might conclude that the second car is expensive.

In health care, such unconscious biases can lead to disparate treatment of patients and can affect whether similar patients live or die.

Sometimes these cognitive biases are simple overreactions to recent events, what psychologists term availability bias. One study found that when patients experienced an unlikely adverse side effect of a drug, their doctor was less likely to order that same drug for the next patient whose condition might call for it, even though the efficacy and appropriateness of the drug had not changed.

A similar study found that when mothers giving birth experienced an adverse event, their obstetrician was more likely to switch delivery modes for the next patient (Csection vs. vaginal delivery), regardless of the appropriateness for that next patient. This cognitive bias resulted in both higher spending and worse outcomes.

This list of biases is far from exhaustive, and though they may be disconcerting, uncovering new systematic mistakes is critical for improving clinical practice. Given our growing understanding of the errors that doctors can make, these biases are too costly to ignore.