'Anchoring bias' can delay testing and diagnosis by physicians for deadly conditions like blood clots in the lung

Finding evidence of what is known as "anchoring bias," UCLA-led research suggests that patients with congestive heart failure experiencing shortness of breath are less likely to be tested in the emergency department for a potentially fatal pulmonary embolism, or a blood clot in the lung, when the reason for the visit noted during the initial emergency department check-in process specifically mentions congestive heart failure instead of the broader "shortness of breath."

Specifically, the authors found in this study that when the visit reason mentioned a patient's known congestive heart failure, the likelihood that the emergency room physician would test the patient for pulmonary embolism was reduced by one-third, even though that could be the cause of the shortness of breath. The study was published June 26 in JAMA Internal Medicine.

Rates of pulmonary embolism within 30 days of the emergency department visit were equal between patients with visit reasons that mentioned congestive heart failure and patients that did not have such visit reasons, suggesting that anchoring bias may have led to delays in diagnosis.

Cognitive biases are believed to influence physician decision making. Among them is anchoring bias, which is when a physician focuses on a single, initial piece of information in the clinical decision-making process without sufficiently considering subsequent information about the patient's condition.

The researchers examined Veterans Affairs data from 108,000 patients with congestive heart failure who went to emergency departments with shortness of breath between 2011 to 2018. They compared patients with visit reasons that mentioned their congestive heart failure to patients with visit reasons that were broader in nature. Anchoring bias can delay crucial testing for and diagnosis of deadly medical conditions such as pulmonary embolism.

"We find evidence that anchoring bias can lead physicians astray," said lead author Dr. Dan Ly, assistant professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA. "When a more specific diagnosis is suggested early on, even before the physician has met the patient, physicians can 'anchor' on this diagnosis and miss important and dangerous alternative conditions. It's important for physicians to be aware of such cognitive biases and keep an open mind, and for those on the medical team not to anchor their colleagues when relaying information."