When doctors make bad calls | The Globe and Mail

Cognitive traps are a  human trait, but doctors are held to a higher standard with the risk of fatal outcomes.

Statistics show that 10 to 15 per cent of patients are misdiagnosed; the number is likely higher, since many medical errors are never discovered.

A 2001 study estimated that one in five mistakes occur because the system fails – a report is lost or a test is inaccurate.  [….]

But that means roughly 80 per cent of mistakes are physician error.  [….]

Some mistaken or delayed diagnoses may be impossible to prevent when a disease is just too rare, the symptoms too generic. And luckily, the harm caused by a mistake is most often stress and worry, plus further clogging of the system as patients return for appointments.

But other mistakes can be deadly. A Canadian study in 2004 estimated that 9,000 to 23,000 Canadian patients die yearly after a preventable “adverse event,” such as surgical errors and improperly prescribed medications.

An Ontario study published last year, which looked at 22 million patients visits from 2003 to 2007, found that the longer patients waited in a crowded emergency room – only to be discharged and sent home – the more likely they were to die or be admitted to hospital within seven days.  [….]

Canadian physicians are among the best trained in the world; their error rates are on par with other industrialized countries. But, like all of us, their fallible human brains mess them up. They stumble unwittingly into false assumptions and snap judgments. “When you hear hoof beats, think horses, not zebras,” the old saying goes. But every year, thousands of patients, such as my husband, are zebras. And too often, doctors don’t look closely enough to see the stripes.


Psychologists have identified about 100 different cognitive traps people generally fall into – shortcuts to quick decisions that, once upon a time, probably saved us from being eaten. In a medical context, for example, doctors are susceptible to overconfidence bias (relying too much on intuition), diagnosis momentum (accepting a previous doctor’s findings without enough skepticism) and availability bias (concluding that a new patient has the same problem as a recent patient with similar symptoms). Those mental miscues are even stronger when the correct diagnosis is a rare one.

Doctors also aren’t immune to stereotypes. They may judge a patient on appearance, gender or race. They may be misled because someone has come in smelling like alcohol or is snappish in the examining room.

Extended article at “When doctors make bad calls” | Erin Anderssen | Feb. 25, 2012 | The Globe and Mail at http://www.theglobeandmail.com/life/health/new-health/health-news/when-doctors-make-bad-calls/article2349755/singlepage/#articlecontent.

Additional information on “Cognitive Traps” | Harriet Hall | May 10, 2011 | Science-Based Medicine (blog) at http://www.sciencebasedmedicine.org/index.php/cognitive-traps/

When doctors make bad calls - The Globe and Mail