In reply: Cognitive bias and diagnostic error (November 2015)

IN REPLY: We thank Dr. Field for his insights and personal observations related to diagnosis and biases that contribute to diagnostic errors.

Dr. Field’s comment about the importance of revisiting one’s initial working diagnosis is consistent with our proposed diagnostic time out. A diagnostic time out can incorporate a short checklist and aid in debiasing clinicians when findings do not fit the case presentation, such as lack of response to diuretic therapy. Being mindful of slowing down and not necessarily rushing to judgment is another important component.¹ Of note, the residents in our case did revisit their initial working diagnosis, as suggested by Dr. Field. Questions from learners have great potential to serve as debiasing instruments and should always be encouraged. Those who do not work with students can do the same by speaking with nurses or other members of the healthcare team, who offer observations that busy physicians might miss.

Our case highlights the problem that we lack objective criteria to diagnose symptomatic heart failure. While B-type natriuretic factor (BNP) has a strong negative predictive value, serial BNP measurements have not been established to be helpful in the management of heart failure.² Although certain findings on chest radiography have strong positive and negative likelihood associations, the role of serial chest radiographs is less clear.³ Thus, heart failure remains a clinical diagnosis in current practice.

As Dr. Field points out, the accuracy and performance characteristics of diagnostic testing, such as the respiratory rate, need to be considered in conjunction with debiasing strategies to achieve higher diagnostic accuracy. Multiple factors can contribute to low-performing or misinterpreted diagnostic tests, and inaccurate vital signs have been shown to be similarly prone to potential error.⁴

Finally, we wholeheartedly agree with Dr. Field’s comment on unnecessary testing. High-value care is appropriate care. Using Bayesian reasoning to guide testing, monitoring the treatment course appropriately, and eliminating waste is highly likely to improve both value and diagnostic accuracy. Automated, ritual ordering of daily tests can indicate that thinking has been shut off, leaving clinicians susceptible to premature closure of the diagnostic process as well as the potential for “incidentalomas” to distract them from the right diagnosis, all the while leading to low-value care such as wasteful spending, patient dissatisfaction, and hospital-acquired anemia.⁵ We believe that deciding on a daily basis what the next day’s tests will be can be another powerful debiasing habit, one with benefits beyond diagnosis.

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