Monday, May 16, 2016


One study estimates that 80,000-160,000 patients a year are affected by serious misdiagnoses, such as failing to diagnose a heart attack, stroke, or cancer, whereas another study estimated that about 40,000-80,000 patients a year die of misdiagnoses.

Physicians tend to estimate lower misdiagnosis rates. A 2011 survey on diagnostic errors by QuantiaMD, collaborating with Dr Wachter, polled more than 6400 clinicians—almost three quarters of whom were physicians. Only about one half said that they came across a misdiagnoses at least once a month in their healthcare setting – a much lower rate than 5% of all diagnoses, and more in line with estimates of serious misdiagnoses.

Furthermore, the clinicians were skeptical that many misdiagnoses could be prevented. Whereas almost 90% agreed that errors were "sometimes" preventable, only 8% said they were "always" preventable. They were also skeptical that a protracted campaign could lower misdiagnoses: Sixteen percent were very confident that errors would fall, 67% were only somewhat confident, and 17% were not confident.

This skepticism may have to do with how these clinicians saw misdiagnoses coming about. Three quarters cited "atypical patient presentation," which cannot be addressed by improving' one's diagnostic reasoning.

In the QuantiaMD survey, one half of respondents said that one of the top causes of misdiagnoses was "failure to consider other diagnoses," which might be addressed by improving one's diagnostic reasoning, but three quarters cited "atypical patient presentation."…

Many misdiagnoses of common diseases involve an atypical presentation. In a 2005 study,[10] 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….

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…

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…

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…

One way to provide feedback to physicians is to create a voluntary error reporting system, which is what the Maine Medical Center in Portland has done. Robert Trowbridge, MD, a hospitalist at the medical center who helped create the program, says the program gets about two reports a week. Clinicians can anonymously report errors, and most of the reports come from someone other than the person who made the error, he says. The report is confirmed by a review of the patient's medical records….

Dr Trowbridge says the program takes steps to keep the information from plaintiff's attorneys in malpractice cases. After the cases are analyzed, patient and physician identifiers are removed and medical record numbers are discarded, he says.

However, on the basis of national estimates, the program captures only a small percentage of diagnostic errors. Many reformers want to create a more robust database…

A search algorithm, called a "trigger," identifies patients who had been treated and then had the same symptoms later—suggesting that the diagnosis had been inaccurate. Then physicians perform detailed chart reviews on these patients to confirm a misdiagnosis.

Gurpreet Dhaliwal, MD, a professor of clinical medicine at UCSF, has been a proponent of examining and improving one's own cognitive processes in making diagnoses, called "metacognition." For example, he reviews case reports in medical journals to get an idea of how the diagnostic process needs to be adjusted. "Once you know your brain is capable of making errors, you're going to be more careful about the diagnoses you make," he says.

Dr Wachter, who teaches residents at UCSF, says younger physicians are taking metacognition more seriously. When reviewing cases at morbidity and mortality conferences, "I hear my residents refer to things like an 'anchoring error' [when the doctor clings to an initial impression, despite contradictory information coming later]," he says. "You didn't hear that term 10 years ago."…

The movement to reduce misdiagnoses is gathering momentum, but it's still not clear yet how successful it can be. Few healthcare organizations are addressing the problem, and many physicians are still skeptical that diagnostic errors can be identified and averted. In addition, payment systems have to be changed to allow physicians to spend more time on diagnoses.

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