CHICAGO – As physicians, clinical lab professionals and research scientists gathered at the American Association for Clinical Chemistry's (AACC; Washington) annual meeting to learn about new advances in diagnostics and disease management, a physician kicked off the meeting by challenging them to approach diagnostic thinking differently to avoid mistakes.
"If you dig very deep into the literature, about 80% to 85% of the time we make the correct diagnoses," said Jerome Groopman, MD, a physician at Harvard Medical School (Cambridge, Massachusetts) and a researcher delving into the basic mechanisms of cancer and AIDS. "If we had baseball hitters who were batting 800-850 it would be unimaginable. If 85% of the financial investment were winners, you'd make millions. But here it's different because the stakes are different ... people's lives. If 15% of all patients are not diagnosed correctly or have a significant delay of diagnosis, it causes harm to patients and that's a problem. It's a problem of a different dimension than what's in the Institute of Medicine (Washington) report of 1999, To Err is Human."
Groopman, a hematology and oncology specialist who has produced seminal work in the development of today's AIDS therapies such as AZT and 3TC, last year published a book, How Doctors Think, and on Sunday laid out his theories on how and why healthcare professionals fall into diagnostic traps.
He presented a series of examples such as this one: A woman in the midst of menopause visited four physicians saying she felt as though she was having periodic explosions in her body.
"When it's 4:45 p.m. on Friday afternoon and you've seen dozens of patients and in comes a jittery woman in the middle of menopause, all of your stereotypes and judgmental baggage goes boom," Groopman said. "Another wacko woman who can't handle menopause. That's the prejudice.
"Then she goes to a fifth doctor, an endocrinologist. She says 'I know I'm in menopause and it's no picnic. I'm a little kooky and high strung, but I'm telling you I feel explosions off and on at the weirdest times.' So instead of attributing this to a kooky woman with menopause, the doctor asked what else it could be."
It turns out the woman had a tumor that was occasionally rupturing.
"This fifth doctor probably saved her life," Groopman said.
Misdiagnoses aren't due to technical mistakes like getting the wrong lab values or X-rays, but because doctors fall into a thinking trap.
"The human mind is wired to take shortcuts," he said. "We overly weigh the first bit of data that we get. All clinicians at the bedside think probabilistically. But I don't know many people who walk around with calculators to calculate theories. It turns out the doctor's mind works like a magnet. It doesn't move in a linear way, strictly on history, exam, lab results and imaging – until the entire data set is in. Doctors think by pulling in bits of data from all directions like a magnet."
Another example: A doctor he knew was working on a Navajo reservation amidst an influenza epidemic.
"An elderly woman came in who didn't feel well," he said. "She's breathing quickly. Chest X-ray is clear. Maybe she's dehydrated? He draws blood and white count is a bit off, chloride and bicarb are funny. He assumes influenza/pneumonia."
As it turns out, the woman had aspirin toxicity.
"What was most available in his mind was flu because everyone had flu," Groopman said. "But the real punch line is that after residency this doctor has done a special fellowship in decision analysis. And he has written a paper on aspirin toxicity. In the real world, working under pressure, you take shortcuts. Sometimes they work, but maybe 15% of the time you fall into the trap."
The genesis of misdiagnosis starts with a theory called anchoring, based on the idea that healthcare professionals put too much emphasis on the first pieces of information received and grab a hold or anchor their thoughts. The next step down the misdiagnosis path is called availability, illustrated via the influenza example.
"Confirmation bias is very common," he said. "Once our mind has fixed on what we think is the answer, when we get contrary data, we rationalize it away and discount it. You look and cherry pick the data that confirm your hypothesis and you discount things that don't fit"
Finally, there's attribution, which is all about biases and cultural stereotypes, such as the woman with menopause and a tumor.
Despite the fact that clinical visit times with patients have collapsed to 12 minutes or less, Groopman said it's key for doctors to do a better job of listening, and try to avoid interrupting the patient within the first 18 seconds, which is typical. But beyond that, doctors – along with lab professionals – can incorporate a series of questions at the bedside or in the lab when making a diagnosis:
1. What else could it be? "This protects you against most of the sins of anchoring, availability and attribution. All of us want to grab ideas, make them fit and move on," he said.
2. Is there anything in the history of the patient, exam, lab results or procedures that have occurred that might contradict an initial conclusion? "This protects against confirmation bias," he said.
3. Could two things be going on at once? "Old theories say you should always look for one unifying hypothesis to say 'it's this.' That sounds great, but God didn't make us that way. Sometimes two things happen at once," he said.
Groopman pointed out that clinicians and lab professionals easily reach into computers and use information technology to aid with diagnostics, but "We have not reached into cognitive thinking about how we think, called metacognition. And I wanted to introduce to you to this whole new field of science. I was completely ignorant."