It's time to talk about why medical misdiagnosis of the so-called Big Three conditions are scarily high.

By Karen Pallarito
May 21, 2020
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Diagnostic errors in medicine are a longstanding problem. Now a new study puts a fine point on the frequency of misdiagnosis in America: It happens more often than you might think, sometimes with tragic consequences.

Researchers at Johns Hopkins University School of Medicine in Baltimore and Boston-based data analytics firm CRICO Strategies scoured the US medical literature to assess rates of diagnostic errors and harms. Their analysis honed in on the top five most frequently misdiagnosed conditions in each of three categories: vascular events (such as heart attack and stroke), infections, and cancers.

In all, nearly one in 10 patients with symptoms caused by one of these so-called Big Three conditions were misdiagnosed, the study found. Not surprisingly, certain conditions were more likely to be associated with a faulty diagnosis than others. Rates of misdiagnosis ranged from 2.2% for heart attacks to a whopping 62.1% for spinal abscess. Overall, the authors estimate that one in 20 people with a Big Three misdiagnosis will suffer serious harm. The 15 conditions included in the analysis account for nearly half of serious misdiagnosis-related harms in malpractice claims, they note.

The study, published online May 14 in the journal Diagnosis, advances the discussion about diagnostic errors in US medicine by quantifying erroneous diagnoses—and the harm they can inflict. Turns out the medical profession doesn’t have a grasp on exactly how many people fall victim to diagnostic flubs.

“There is no mechanism for tracking the diagnostic error rate, so we don’t know what it is in clinical practice,” lead author David Newman-Toker, MD, PhD, director of the Armstrong Institute Center for Diagnostic Excellence at Johns Hopkins University School of Medicine in Baltimore, tells Health. The new study is the second in a series of three aimed at estimating the number of people who are seriously injured, permanently disabled, or die each year due to diagnostic errors, “which I can tell you will be in the hundreds of thousands,” he says. The third study in the series, which he expects to be published in the next six months, will provide a more precise estimate.

Here’s what doctors are missing—and why

So why do these errors keep happening? There is no single explanation. Sometimes it can be a common malady that trips doctors up. A stroke that doesn’t present with the usual facial droop or speech difficulties might be misinterpreted, for instance. As Dr. Newman-Toker explains, “We don’t miss strokes when someone’s paralyzed on one side and can’t talk.…We only miss strokes when they’re subtle, when they’re not obvious.” Only 3 to 5% of dizziness is due to stroke, researchers noted in the report

While the rate of stroke-related diagnostic errors, at 8.7%, falls at the lower end of the error-rate spectrum, the frequency of stroke in America is high, so any mistakes made in detecting these neurological events have the potential to impact a lot of people. “We miss about 40% of the strokes when they present with dizziness and vertigo,” says Dr. Newman-Toker.

Often, though, it’s the uncommon conditions in medicine that lead to diagnostic mishaps. The research team found that certain rare infections (like an abscess in the spine, which can lead to paralysis if left untreated) and vascular issues (especially aortic aneurysm and dissection, a life-threatening ballooning and tearing of the major artery in the body) were more likely to be missed.

As for cancer misdiagnoses, the authors suspect that errors may be related to inadequate screening or treatment. Lung cancer is one diagnosis for which screening remains sub-par, and when you’re diagnosed later in the course of the disease, your therapeutic options are more limited, they explain, which can lead to poorer outcomes. More than one in five lung cancer diagnoses (22.5%) were “meaningfully delayed,” notes the Society to Improve Diagnosis in Medicine (SIDM), which funded the study via a grant from the Gordon and Betty Moore Foundation.

“A clinically meaningful delay,” as the study authors explain, “is a function of underlying disease biology and natural history—for colorectal cancer, delays up to ~6-9 months likely have no impact; for aortic dissection, minutes probably count.”

Credit: Alex Sandoval - Getty Images

The damage of medical errors

In addition to calculating rates of misdiagnosis, researchers assessed the harms that errors in diagnosis inflict. Take heart attack, as an example. Only about 2% of these patients are misdiagnosed, which is still a lot of people given the frequency of these events, Dr. Newman-Toker is quick to point out. Still, only about 1% of heart attack patients suffer serious harm as a result of being misdiagnosed. By contrast, the diagnostic-related harm rate for meningitis and encephalitis, at over 14%, is many times higher. The harm rate was highest for spinal abscess, at 36.5%.

So why are heart attack patients less likely to experience poor outcomes? Dr. Newman-Toker says it’s a “shining star” example of how medicine gets it right: “We’ve made it a priority to diagnose heart attacks quickly. What we need to do is make it priority to diagnose these other 14 things that we haven’t made a priority, because if we tackle those, we’ve estimated that we could take out almost half of the diagnostic-error problems just by addressing these 15 diseases.”

Toward that end, legislation introduced in the US House of Representatives last November would fund new “research centers of diagnostic excellence” at US academic medical centers, says SIDM. The bipartisan “Improving Diagnosis in Medicine Act” represents “an important first step as we begin to tackle a problem that is costing hundreds of thousands of lives and likely over 100 billion annually in wasted health care dollars,” Paul Epner, the Society’s CEO and co-founder, said in a news release announcing the study findings.

What patients can do to cut the risk of misdiagnosis

Accurately diagnosing vascular events, infections, and cancers will require a multifaceted approach, says Dr. Newman-Toker. There needs to be greater teamwork and training, better use of technology, and feedback to help clinicians fine-tune their efforts.

But patients can also do their part. He tells patients to come prepared for their visit: summarize your problem, focusing on your symptoms and the order of events. During the visit, ask the clinician: “What is the worst thing you think this could be, and tell me why you think it’s not that.” That gives you a gauge, he explains. “If they sort of blow you off and say, ‘Oh don’t worry about it; you’re fine,’ get yourself a new doctor.” If the doctor gives you a cogent, thoughtful answer, that’s a good sign.

After the visit, it’s critically important to stay vigilant. Patients often wrongly assume if their symptoms or problems don’t improve, it’s because the treatment isn’t working, and that isn’t necessarily the case, says Dr. Newman-Toker. “It may not actually be that you have the wrong treatment or the treatment isn’t working; it may be that you have the right treatment for the wrong disease,” he says.

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