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The Silence Surrounding Diagnostic Errors; Part I
This post was written by Maggie Mahar and Niko Karvounis

Despite all of the talk about medical errors and patient safety, almost no one likes to talk about diagnostic errors. Yet doctors misdiagnose patients more often than we would like to think. Sometimes they diagnose patients with illnesses they don’t have. Other times, the true condition is missed. All in all, diagnostic errors account for 17 percent of adverse events in hospitals according to the “Harvard Medical Practice Study,” a landmark study that looks at medical errors.

Traditionally, these errors have not received much attention from researchers or the public. This is understandable. Thinking about missed diagnosis and wrong diagnosis makes everyone—patients as well as doctors—queasy. Especially because there is no obvious solution. But this past weekend the American Medical Informatics Association (AMIA) made a brave effort to spotlight the problem, holding its first-ever “Diagnostic Error in Medicine” conference.

Hats off to Bob Wachter, Associate Chairman of the Department of Medicine at the University of California, San Francisco, and the keynote speaker at the conference. On Monday, Wachter shared some thoughts on diagnostic errors through his blog, “Wachter’s World.”

Wachter begins by pointing out that a misdiagnosis lacks the concentrated shock value that is needed to grab the public imagination. Diagnostic mistakes “often have complex causal pathways, take time to play out, and may not kill for hours [i.e., if a doctor misses myocardial infarction in a patient], days (missed meningitis) or even years (missed cancers).” In short, to understand diagnostic errors you need to pay attention for a longer period of time—not something that’s easy to do in today’s sound-bite driven culture.

Diagnostic errors just aren’t media friendly. When someone is prescribed the wrong medication and they die, the sequence of events is usually rapid enough that the story can be told soon after the tragedy occurs. But the consequences of a mistaken diagnosis are too diffuse to make a nice, punchy story. As Wachter puts it: “They don’t pack the same visceral wallop as wrong-site surgery.”

Finally, Wachter observes, it’s hard to measure diagnostic errors. It’s easy get an audience’s attention by telling them that “the average hospitalized patient experiences one medication error a day” or that “the average ICU patient has 1.7 errors per day in their care.”...


...Medicine is shot through with uncertainty; diseases do not always present neatly, in textbook fashion, and every human body is unique. These are just a few reasons why diagnosis is, perhaps, the most difficult part of medicine.

But misdiagnosis almost always can be traced to cognitive errors in how doctors think. When diagnosis is based on simple observation in specialties like radiology and pathology, which rely heavily on visual interpretation, error rates probably range from 2 percent to 5 percent, according to Drs. Eta S. Berner and Mark L. Grabe, writing in the May issue of the American Journal of Medicine.

By contrast, in clinical specialties that rely on “data gathering and synthesis” rather than observation, error rates tend run as high as 15 percent. After reviewing “an extensive and ever-growing literature” on misdiagnosis, Berner and Grabe conclude that “diagnostic errors exist at nontrivial and sometimes alarming rates. These studies span every specialty and virtually every dimension of both inpatient and outpatient care.”...