The most dramatic case that Steven M. Levin, JD, founder and senior partner at Levin & Perconti in Chicago, ever handled involving the tragic consequences of "anchoring" when a pediatrician failed to diagnose a young child with cystic fibrosis. Anchoring is a cognitive error that occurs when a physician latches on to the first diagnosis that comes to mind.
"The doctor sent the child for a test that, at best, was 50% accurate at diagnosing cystic fibrosis," says Levin. "When the test came up negative, the doctor incorrectly assumed the child did not have cystic fibrosis."
The physician then spent years trying to interpret the facts of this child's clinical condition into little-known illnesses, and never retested the child because he "anchored" on the negative result of the previous test. "Even in his deposition, he would not acknowledge that his incorrect diagnosis was based on the faulty test," says Levin.
Robert M. Wachter, MD, professor and associate chairman of the Department of Medicine at University of California — San Francisco, has reviewed many malpractice claims whose root cause was anchoring. "I'm seeing such anchoring occur more and more often in training settings because of the house staff duty hour reductions," he reports.
About one-third of the patients on a typical ward team now will be admitted by a different set of physicians on night shift and then handed to the team that will have primary responsibility at 8 a.m. "Even with very smart residents, the night doctor will get something wrong about one time in five," says Wachter.
It is terribly hard for the day team, who are busy accepting several handoffs, to "rethink things and ask, 'Does this all really make sense?'" says Wachter. "Heart failure with a [brain natriuretic peptide level] of less than 100? Low blood pressure from sepsis with no fever or elevated [white blood cell count] ... Really?"
Mental tricks needed
It is not uncommon for physicians to accept their own diagnosis or that of a trusted colleague, even in the face of evidence pointing to an alternative.
"We need to create mental tricks to push ourselves to not take the 'easy' way out, but to really question things," says Wachter.
Wachter teaches physicians to question everything; taking the view that their predecessor hasn't made any diagnoses, but rather, has developed some hypotheses. He advises physicians to ask the question, "What would I expect to find on the physical exam?" after hearing the patient's history and a similar question before viewing laboratory or X-ray results.
"This allows physicians to retain the capacity for surprise," he says, such as recognizing that they would have expected crackles at the base and a fever with a diagnosis of pneumonia. The fact that the patient's lungs are clear then would lead the physician to suspect pulmonary embolism.
Wachter also advises physicians to ask, "If I'm wrong, what is the worst diagnosis that I could be missing here?"
Shortcuts lead to errors
"Heuristics" are shortcuts that physicians use to make complex situations easier to tackle, but these shortcuts can lead to cognitive errors, warns Alexis Ogdie-Beatty, MD, assistant professor of medicine and epidemiology in the Division of Rheumatology at the University of Pennsylvania in Philadelphia.
"There are several cognitive errors that physicians need to be aware of," she says. These include:
- framing bias — letting what others tell you about a patient influence your thought process without thinking through the process on your own;
- diagnostic momentum — assuming a previously noted diagnosis is correct without rethinking the diagnosis;
- visceral bias — allowing negative or positive feelings about a patient to influence the diagnosis made.1 (For more information on cognitive errors that can lead to malpractice suits, see related story, p. 87.)
Ogdie-Beatty and colleagues teach workshops to resident physicians in which she suggests asking these four questions to avoid cognitive bias after arriving at a potential diagnosis: What else can it be? Is there anything that doesn't fit? Is it possible that there's more than one thing going on? Is this a case in which I need to slow down?2
"Physicians should also reflect on their thinking process," says Ogdie-Beatty. "They should consider times when they may be most at risk for these errors, such as when they are unusually busy or distracted."
- Croskerry, P. The importance of cognitive errors in diagnosis and strategies to minimize them. Acad Med 2003; 78:775-780.
- Trowbridge, RL. Twelve tips for teaching avoidance of diagnostic errors. Medical Teacher 2008: 30:496-500.