How anchoring bias can impact ED diagnoses

Key takeaways:

• Physicians may anchor on initial information, like a congestive heart failure diagnosis, when making decisions in the ED.
• Anchoring bias was associated with delayed pulmonary embolism diagnoses.

Physicians may anchor on initial information when making decisions, a habit that was associated with delayed diagnoses, according to the results of research published in JAMA Internal Medicine.

“Cognitive biases, or ways of thinking that may deviate from rationality, are thought to influence how physicians make these decisions, but there has been little large-scale evidence of their existence clinically,” Dan P. Ly, MD, PhD, MPP, a physician and assistant professor in the division of general internal medicine and health services research at UCLA’s David Geffen School of Medicine, told Healio.

Anchoring bias is when a physician focuses on just one — usually the first — piece of information that is presented when formulating a diagnosis “without sufficiently adjusting to later information,” Ly and colleagues wrote. It is thought to be one of the most common cognitive biases that affect physicians.

“Anchoring bias is often accompanied by the framing effect, under which physicians are influenced by how the problem is presented, and by ascertainment bias, under which physicians, once framed, see what they expect to see,” Ly and colleagues wrote.

The researchers conducted the study to see if physicians who saw patients with congestive heart failure (CHF) presenting to the ED with shortness of breath (SOB) were less likely to test these patients for pulmonary embolism (PE) if the documented reason for the visit mentioned CHF.

Ly and colleagues conducted a cross-sectional study of Veterans Affairs data from 2011 to 2018, which included 108,019 patients with CHF presenting with SOB, 4.1% of whom had CHF mentioned in the documented patient visit reason section. The researchers conducted the analyses from July 2019 to January 2023.

Of the 4.1% of patients who had CHF mentioned in the documented patient visit reason section, 71.4% received B-type natriuretic peptide testing, 13.2% received PE testing (on average within 76 minutes), 0.23% were diagnosed in the ED with acute PE and 1.1% were eventually diagnosed with acute PE.

In adjusted analyses, mention of CHF at the outset was linked to 15.5 more minutes (95% CI, 5.7-25.3) to PE testing, a 4.6 percentage point (95% CI, 5.7 to 3.5) reduction in PE testing and a 6.9 percentage point (95% CI, 4.3-9.4) increase in B-type natriuretic peptide testing, “which is commonly ordered to assess for CHF exacerbation,” the researchers wrote.

“Among patients who all had congestive heart failure, when the “visit reason” that was put down during the emergency department check-in process, before seeing the physician, mentioned congestive heart failure, physicians were less likely to test for the deadly, can’t-miss condition of PE, or blood clots in the lung,” Ly said. “This occurred even though mention of congestive heart failure had no association with likelihood of pulmonary embolism.”

The results, Ly and colleagues wrote, “are consistent with physicians anchoring on initial information.”

Although the researchers did not observe a significant association between the mention of CHF and ultimately diagnosed PE (0.06 percentage point difference; 95% CI, 0.23 to 0.36), mention of CHF was additionally associated with a 0.15 percentage point (95% CI, 0.23 to 0.08) lower likelihood of PE diagnosis in the ED.

Ly and colleagues concluded that "presenting physicians with the patient’s general signs and symptoms, rather than specific diagnoses, may mitigate this anchoring.”

“When sending referrals to specialists, it might make most sense not to mention what you think the diagnosis is,” Ly told Healio. “Just write ‘leg pain’ or ‘chest pain,’ not ‘sciatica’ or ‘stable angina.’”