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Carolyn Thomas recently had a heart attack that was misdiagnosed. (Geoff Howe for The Globe and Mail/Geoff Howe for The Globe and Mail)
Carolyn Thomas recently had a heart attack that was misdiagnosed. (Geoff Howe for The Globe and Mail/Geoff Howe for The Globe and Mail)

When doctors make bad calls Add to ...

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. That's disconcerting when we know that more Canadians, unable to find family doctors, are using the ER as an alternative. The problem may get only worse.

Certainly, system failure is a factor: Faced with bed shortages and lengthy test delays, doctors may lower their risk threshold, sending home patients who, at slower times, would be kept for observation, speculates the study's co-author, Michael Schull, an emergency physician at the Sunnybrook Health Sciences Centre and the director of emergency medicine at the University of Toronto. Stressed-out, overworked doctors, seeing too many patients in too short a time, may be less likely to collect full patient histories or check drug interactions, or spend as much time explaining the follow-up steps to a patient. Their decision-making processes are essentially overloaded, increasing the chance that cognitive bias may cause a rash misdiagnosis.

Some Canadian ER physicians, such as Brian Goldman of Mount Sinai Hospital in Toronto, who hosts the program White Coat, Black Art on CBC Radio, have publicly challenged doctors to more openly share their errors with colleagues. (See his TED talk here.)

“The culture of medicine has an almost immunological response to error: The first instinct is to send out the antibodies and try to contain the contagion and get rid of it,” Dr. Goldman says, citing a survey of 1,800 American physicians released this month that found 20 per cent had kept mum about a mistake. Clearly they fear lawsuits, but that's not all. “Underneath is this terrible insecurity that many physicians feel, that they'll be caught out on a mistake and people will find out that they are not perfect, and somehow admitting you make mistakes is the first step in being asked to leave the profession. … We're ashamed to talk about it.”

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.

The persistent rate of misdiagnosis has spurred a new conversation about how to teach medical students better, how to open up discussion about mistakes in hospitals and how patients themselves might play a role in preventing false conclusions. For instance, Dalhousie University is developing a new critical-thinking program for pre-med students. In December, Quebec became the first province to publish a standardized registry of errors, although already some hospitals have been criticized for filing incomplete reports.

“We need to train physicians to understand how decisions are made and how to think more critically,” says Pat Croskerry, a Halifax emergency-room physician and the director of medical education at Dalhousie, where he is developing the school's new curriculum. “A number of people think this is one of the next major hurdles in medicine.”

Cognitive missteps

In May, 2008, Carolyn Thomas, a 58-year-old communications co-ordinator, walked into an emergency department in Victoria. She was feeling a pain down her left arm, nausea and a crushing tightness in her chest. She didn't have to wait long – it was morning and not crowded and she had worrisome symptoms – but the doctor she saw barely made eye contact, and his manner was curt and rushed. He ordered a treadmill test and an electrocardiogram. The tests came back normal.

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