Anchoring Bias Lyme Disease: When Diagnosis Goes Wrong

Anchoring bias Lyme disease errors can occur when clinicians fixate on an initial diagnosis
and fail to adequately adjust their thinking as new information emerges. Conversely, this
same cognitive bias may also occur when Lyme disease is incorrectly diagnosed and the true
underlying illness is missed.

Aguirre and colleagues describe such a scenario in their paper,
Anchoring Bias, Lyme Disease, and the Diagnosis Conundrum.

Case Report: Suspected Lyme Disease

A 29-year-old man living in Florida presented with severe headaches, fever, myalgia, and
diarrhea. “He developed facial paresis with nonfocal paresthesia, bilateral scotomas, and a
self-resolved erythematous patch along his inner thigh weeks prior,” the authors report.

“Initial suspicion for early disseminated Lyme with aseptic meningitis was fueled by tick
exposure, cutaneous exanthem, and facial palsy,” writes Aguirre.

Laboratory testing revealed a positive IgM Western blot and a negative IgG for
Borrelia burgdorferi. Based on these findings, clinicians initially diagnosed early
disseminated Lyme meningitis and prescribed doxycycline.

Diagnostic Reassessment and Final Diagnosis

After additional testing, the diagnosis was revised. The patient was ultimately found to
have Echovirus 30 and Coxsackie B5 infection.

The authors concluded that the initial diagnosis of Lyme disease represented an example of
anchoring bias.

“His headache and vision improved gradually,” writes Aguirre. “However, the patient
experienced distress from misdiagnosis with a life-threatening and contagious illness,
affecting family contact and resulting in financial burden from prolonged work leave.”

Clinical Perspective on Anchoring Bias and Lyme Disease

Editor’s note:
I am not convinced that this case represents a clear example of anchoring bias.

Lyme disease does occur in Florida.

“Of 216 regional cases reported in 2016, 132 were confirmed positive by the CDC,”
writes Aguirre.

I also disagree with the authors’ suggestion that anchoring bias could have been avoided
through strict adherence to the CDC two-tier testing algorithm.

Only 25% of patients with early Lyme disease test positive using two-tier testing,
according to a 2017 study published in Clinical Infectious Diseases. Furthermore,
only 55% of early Lyme patients had positive results on convalescent testing.

It is common and appropriate medical practice to treat suspected infections empirically
while awaiting test results. It is equally appropriate to revise a diagnosis as new
clinical or laboratory information becomes available.

This case highlights the complexity of diagnosing Lyme disease and the risk of labeling
thoughtful clinical decision-making as anchoring bias in conditions where diagnostic
certainty is inherently limited.