Errors Due to Atypical Presentation and Rare Diseases
Diagnoses can be sidetracked by atypical disease presentation and by rare diseases that the doctor has never seen before.
Studies show that most errors involve common diseases. In a 2013 study, the most common misses were pneumonia (6.7%), decompensated congestive heart failure (5.7%), acute renal failure (5.3%), cancer (5.3%), and urinary tract infection (4.8%).
Many misdiagnoses of common diseases involve an atypical presentation. In a 2005 study, Dr Graber and fellow researchers found that of 44 cases of diagnosis errors that were considered "no-fault"—that is, the physician could not be blamed for missing the diagnosis—33 had to do with an atypical or masked disease presentation.
Philip C. Cory, MD, an anesthesiologist in Bozeman, Montana, says both he and his wife had atypical presentations that were misdiagnosed. "Doctors tend to miss the unusual diagnosis," he says.
For about 15 years, Dr Cory says, doctors missed his wife's hypothyroidism because it wasn't picked up by the usual method of a thyroid-stimulating hormone test. In his own case, he went to the emergency department after a spell of dizziness and was diagnosed with benign positional vertigo, but it turned out to be atypical migraine, he says.
Rare diseases can be even more difficult to detect, because the doctor has often never seen the disease before. According to the Shire Disease Impact Report, it takes an average of 7.6 years for a US patient with a rare disease to receive the proper diagnosis. Such patients typically visit up to eight physicians before they get the right diagnosis, the report said.
According to the National Institutes of Health (NIH), a rare disease is one that affects fewer than 200,000 Americans at any given time, but the total impact of rare diseases is significant. There are almost 7000 rare diseases affecting 25 million Americans, the NIH says. Medscape maintains a Rare Diseases site, which provides reports on journal articles and other sources involving rare diseases.
Both atypical presentations and rare diseases require extra spadework, Dr Cory says. "As patients, we want a doctor who has a lot of curiosity—someone who will dig into the case, like Doc Martin or Dr House on TV," he says. "But you don't get that, in many cases." Instead, he says, many doctors agree with the obvious diagnosis. "They don't like ambiguity," or they may be too burned out to care, he says. On the other hand, if they believe they have a correct diagnosis, there's no need to test further.
Last year, Dr Cory and his wife, who holds a PhD in microbiology and immunology, launched a consultancy that works with patients with hard-to-solve cases, in collaboration with their usual physicians. "We like puzzles, and we think we're doing something worthwhile," he says. "Nothing is more distressing than having a significant medical issue and not getting answers."
Although Dr Cory has only had a few patients so far, other physicians have already found a niche in working on challenging diagnoses. Outside New York City, Thomas J. Bolte, MD, bills himself as a "medical mystery investigator" and has been lauded in the media as "the real Dr House." And at the University of Alabama at Birmingham, the Undiagnosed Diseases Program bills itself as "the last hope" for people with mystery diseases.
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Cite this: Leigh Page. Is Misdiagnosis Inevitable? - Medscape - Mar 28, 2016.