What can physicians do to combat confirmation bias?

The day begins at 6 a.m. I am rounding on my nine patients, quickly examining them and providing a brief update about the plan. Like the other harried residents, I am speeding from one room to the next, trying to get everything done on time. And then, inevitably my beeper goes off — “Patient in emergency room being admitted, please call for signout.” I stop in my tracks. I can literally feel the time ticking away, and there is so much to do. But as I clear my mind to hear about the new admission, I have to remind myself of a lesson I learned as a medical student — the importance of slowing down.

Ms. A was a petite woman in her early 40s with beautiful dark hair and a kind smile. She appeared rather calm despite her current woes — double vision and difficulty opening her left eye. I met her when she was admitted to the neurology service. Earlier that day, in the emergency room, a quick physical exam revealed that she had a drooping eyelid, raising concern that her third cranial nerve was injured. A CT scan was performed, which suggested that Ms. A could have a meningioma, a brain tumor compressing the nerve. The patient was admitted to our service for steroid treatment, which is used to prevent further nerve damage. When I met Ms. A, I did not know any of the events in the ER, including the results of her scan. My resident had advised me not to read her chart prior to taking a history and examining her.

When I examined Ms. A’s eyes, I was bewildered. She did, indeed, have a droopy eyelid, but when I held it open, she was unable to look left, right, up or down. I asked her to follow my index finger with her eyes, this time more slowly. Again, I noted that she could not move her left eye at all. So I reasoned, that three nerves were impaired, not just one. There is only one place in the brain where all of these nerves traverse together. It is called the cavernous sinus. Whatever mass was compressing her nerves had to be in that location, and it was virtually impossible that she had a meningioma. Ms. A’s records from a different hospital were obtained, and sure enough, she had a large and growing carotid aneurysm, or ballooning of a major blood vessel, which travels through the cavernous sinus. (The patient had not mentioned this to me.)

The findings caused quite a stir in the workroom. It was the kind of commotion that occurs when we encounter an unusual case. “Did you hear about so and so?” “We never thought that she could have…” A carotid aneurysm is a life-threatening emergency. And if not treated immediately, it can burst and lead to brain death. We contacted the neurosurgery team right away. What Ms. A needed was an urgent surgery — not steroids — to save her life.

Caring for Ms. A was a shock to my system; I was keenly reminded that any misstep by the physician could be life-altering for a patient. Everyone acknowledges that the ER physician’s job is to triage, stabilize, and initiate appropriate workup — not to settle on diagnoses. With tremendous time pressures, any physician can miss a correct diagnosis. It is merely the nature of our business. But what matters is how often and quickly we catch those errors. The thing I wonder most is — are there delays in recognizing mistakes because successive physicians tend to believe their colleagues’ initial impressions? And does a fear of speaking up when it goes against the grain contribute to the delay?

Nowadays, physicians practice medicine as part of large teams, often involving sub-specialists, and that can translate into each individual having decreased ownership of the patient. Furthermore, the system encourages trainees to do exactly as a more senior member of the team asked. And truthfully, our minds have a tendency to follow the path of least resistance when inundated with competing tasks that are all equally important and need to get done immediately. Research suggests that when people are under stress and need to make quick decisions, they develop tunnel vision, become wedded to an idea, and fail to consider alternatives. This confirmation bias is highly prevalent in medicine. We grab on to the first piece of information about a patient and despite knowing it is incomplete, we rely on it heavily to make future decisions. I have certainly been guilty of this, even when I had the luxury of time. We also tend to build our management plans on the foundation laid by the previous physician caring for the patient, which can improve efficiency, but also lead us down the wrong path.

In the case of Ms. A, the ability to approach the case with fresh eyes — to meet the patient without a deluge of information from previous providers — really helped me to see things differently. But when faced with time pressure, it feels like taking a step backward or re-inventing the wheel to gather all the raw data for oneself. And it is unrealistic to not look at a patient’s chart before forming a clinical impression.

So, what can physicians do to combat confirmation bias? I try to live by the principle of trust but verify. Reviewing all of the information in a systematic way every single time, starting with the objective findings (including the physical exam), helps me to stay grounded in the facts and to think independently of others’ opinions. In addition, I keep a running list of incongruous information that does not fit the principal diagnosis, rather than trying to explain it away with hand waving or just ignoring it. This prevents me from becoming too deeply committed to a diagnosis and to maintain a flexible mindset. And finally, I try to illicit dissenting ideas from others. As a resident, I have found that medical students are good at picking up on things that may have been missed by the rest of the team. However, given the hierarchy in medicine, they may not speak up (much less disagree with the residents), unless expressly given the opportunity. Forming a habit of these practices, even when there is little time or when the case is straightforward, is a way to remain inquisitive and to be prepared for patients like Ms. A.

I saw Ms. A the day after her surgery. She could now open her left eye, and her double vision was improving. She thanked me for everything despite the small role that I played in her care. I thanked her for reminding me of something that I am still trying to master as a resident: to see, to listen, to examine and re-examine for oneself, and most importantly, to question and to truly know, even on the most hurried days.

Komal Kothari is an internal medicine resident. 

Image credit: Shutterstock.com

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