More Than 12 Million Patients Are Misdiagnosed Every Year [Infographic]

A major 2014 study found that 12 million US patients, around 5%, are misdiagnosed every year. That’s a huge, scary number, and the research got tons of press. Even non-medical news sources, like CBS, picked up on the story, crafting shocking headlines like “12 Million Americans Misdiagnosed Each Year.” But unfortunately, at least for patients, the study only looked into diagnostic errors affecting outpatients.

According to Dr. Mark L. Graber, a Yale and Stanford-educated patient safety pioneer, and current professor emeritus of medicine at the State University of New York at Stony Brook, misdiagnosis may be far more common than the headlines would lead you to believe. In a comprehensive review of the medical literature on diagnostic errors, published in 2013 by the British Medical Journal, discovered even higher rates of misdiagnosis.

Misdiagnosis Changes, Depending On How You Look At It.

Graber is careful to note that misdiagnosis rates change depending on what method you choose to look at the problem.

Studies that use autopsy reports to confirm a patient’s cause of death, and then search back through medical records to see if doctors got it right before death, are considered the gold standard in this sort of research. When Graber reviewed autopsy studies, he found rates of diagnostic error anywhere between 10% and 20%. Importantly, autopsy studies don’t just focus on outpatients. In fact, they predominantly register patients who died as hospital inpatients, while also including emergency room visits. ER visits, Graber writes, are especially important, since doctors have to make quick diagnostic decisions, and are presented with patients they don’t know. It’s “the natural laboratory for studying diagnostic error,” he says.

Studies that use a “secret shopper” strategy, sending undercover patients in to get real diagnoses, come up with slightly different numbers. Graber found that between 13% and 15% of those secret study subjects were incorrectly diagnosed by physicians who didn’t know they were part of a research project.

Third on Graber’s list are “second review” studies, which get second opinions on a first doctor’s judgment. These studies are fairly simple: hand one doctor a diagnostic test, like a sample of biopsied tissue, and have them diagnose the condition it shows. Then give the sample to a second doctor, and see if their diagnoses match up. Under controlled conditions, this method can have very strong results, since the administrators will pre-diagnose every sample, usually with the help of a board of experts. Looking over several of these studies, Graber found a wide range of error rates, from 10% to an extremely-high 50%. Second review studies are also more specific, since they can only be used to measure diagnostic errors in “visual subspecialties,” like radiology and pathology, where physicians need to visually detect abnormalities based on diagnostic tests.

To look at the rates of misdiagnosis in cancer patients, click here.

But The Consequences Are Unmistakable.

Based upon his review, Graber estimates that the true incidence of diagnostic error is somewhere between 10% and 20%. While that’s a fairly wide range, the number is surely higher than 5%. Wherever one falls on that debate, however, the true implications of misdiagnosis can only be understood after considering the effect diagnostic errors have on real-world patients:

  • Up to 28% of diagnostic mistakes are life-threatening, result in death or disability.
  • 40,000 to 80,000 deaths per year are caused by diagnostic errors. Total medical errors may account for as high as between 210,000 and 440,000 deaths every year, according to recent research in the Journal of Patient Safety. If accurate, those estimates are between 2 and 4.5 times higher than the number cited in the Institute of Medicine’s now-famous 1999 report, “To Err Is Human.”

For doctors, the consequences of a misdiagnosis can be costly, too, although we would never imply that financial losses are equivalent to a loss of human life. Nevertheless, diagnostic errors are the leading cause of malpractice lawsuits, and account for the most payouts. Around 29% of all malpractice settlements are the result of a doctor’s alleged misdiagnosis.

Is Your Doctor Hiding Something?

Of course, patients care about the problem of misdiagnosis instinctively. It affects their lives directly. We think physicians should care, too, but recent signs show a troubling lack of scrutiny is placed on diagnostic errors from within the medical profession. For one, real doctors don’t seem to think they should have to apologize, even when their mistakes result in serious patient harm.

In his wide-ranging review of the evidence, Dr. Mark Graber also looked at the systems hospitals and health networks put in place to track medical errors. He found little evidence to suggest that health care systems were adequately recording diagnostic errors, writing, “diagnostic error rates are being measured in very few, if any, healthcare organisations in the US.”

The Institute of Medicine’s “To Err Is Human” report was heralded as the most comprehensive look at medical errors ever produced when it was released in 1999. No one has come close to matching its breadth and systematic perspective on the American healthcare landscape. Now available in book form, running to 312 pages, the report only includes two references to diagnostic errors. Just two.

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