Recent studies underscore the extent and potential impact of such errors. To cite just two examples:
- In a 2009 report of nearly 600 diagnostic mistakes, a full 28 percent of them were life-threatening or resulted in either death or permanent disability
- Another analysis last year found that 40,500 people die annually due to fatal diagnostic errors in U.S. intensive care units. That's roughly equal to the number of deaths each year from breast cancer.
Misdiagnosis "happens all the time," said David Newman-Toker, who studies diagnostic errors and helped organize the recent international conference. "This is an enormous problem, the hidden part of the iceberg of medical errors that dwarfs" other kinds of mistakes, said Newman-Toker, an associate professor of neurology and otolaryngology at the Johns Hopkins School of Medicine. Studies repeatedly have found that diagnostic errors, which are more common in primary-care settings, typically result from flawed ways of thinking, sometimes coupled with negligence, and not because a disease is rare or exotic.
Despite their prevalence and impact, such mistakes have been largely ignored, Newman-Toker and others say. They were mentioned only twice in the Institute of Medicine's landmark 1999 report on medical errors, an omission some patient safety experts attribute to difficulties measuring such mistakes, the lack of obvious solutions and generalized resistance to addressing the problem.
"You need data to start doing anything," said internist Mark L. Graber, founding president of the Society to Improve Diagnosis in Medicine and a leading errors researcher. Despite dozens of quality measures, Graber said, he is unaware of "a single hospital in this country trying to count diagnostic errors."
In the past few years, a confluence of factors has elevated the long-overlooked issue. In his 2007 bestseller, "How Doctors Think," Boston hematologist-oncologist Jerome Groopman vividly deconstructed the flawed thought processes that underlie many diagnostic errors, including several he made during his long career.
More recently, an influential cadre of medical leaders has been pushing for greater attention to the problem. They cite concerns about the growing complexity of medicine and increasing fragmentation of the health-care system, as well as relentless time pressures squeezing doctors and the overuse of expensive, high-tech tests that have supplanted traditional hands-on skills of physical diagnosis.
Publicity about the death last year of 12-year-old Rory Staunton, sent home from an emergency room in New York after doctors missed the raging systemic infection that quickly killed him, have put a human face on the problem.
"One of the reasons it's time to begin looking at it is that so many of the quality measures we use now assume that the diagnosis is the right one in the first place," said Christine Cassel, president of the American Board of Internal Medicine.
But what if it's not?
In a much-cited essay, Robert Wachter, associate chair of the Department of Medicine at the University of California at San Francisco, wrote that a hospital could earn "performance incentives for giving all of its patients diagnosed with heart failure, pneumonia and heart attack the correct, evidence-based and prompt care -- even if every one of the diagnoses was wrong."
No obvious fix
Unlike drug errors and wrong-site surgery -- mistakes that patient safety experts consider to be "low-hanging fruit" amenable to solutions such as color-coded labels and preoperative timeouts by the surgical team -- there is no easy or obvious fix for diagnostic errors. Many are complex and multifaceted, and may not be discovered for years if ever, said Graber, a senior fellow at RTI International, a research firm based in Research Triangle Park, N.C.
"There is probably nothing more cognitively complicated" than a diagnosis, he said, "and the fact that we get it right as often as we do is amazing."
But doctors often don't know when they've gotten it wrong. Some patients affected by misdiagnosis simply find a new doctor. Unless the mistake results in a lawsuit, the original physician is unlikely to learn that he blew it -- particularly if the discovery is delayed. While diagnostic errors are a leading cause of malpractice litigation, the vast majority do not result in legal action.
There is another reason such mistakes have been long ignored: They are regarded as an unusually personal failure in a profession where diagnostic acumen is considered the gold standard.
"This really gets to who we are as clinicians," said internist Robert Trowbridge, who directs the medicine clerkship program for Tufts University medical students at Maine Medical Center in Portland.
"Overconfidence in our abilities is a major part of the problem," said Graber, who believes doctors have gotten a pass for too long when it comes to diagnostic accuracy. "Physicians don't know how error-prone they are."
Many, he noted, wrongly believe that the problem is "the other guy" and that they don't make mistakes. A 2011 survey of more than 6,000 physicians found that 96 percent felt that diagnostic errors are preventable; nearly half said they encountered them at least once a month.
At Maine Medical Center, Trowbridge spearheaded a pilot program launched in 2010 to persuade doctors to anonymously report diagnostic errors, which would then undergo comprehensive analysis. He said he had to "hound" his colleagues to report mistakes. During the first six months, 36 errors that would otherwise have gone unreported were identified; most were deemed to have caused moderate to severe harm.
