As many as 75% of the errors that occur in internal medicine are tied to flawed clinical reasoning, a study found. In this context, experts stress that identifying and teaching cognitive biases is critical to improving medical practice.

Among the most common cognitive biases encountered in clinical practice are anchoring bias, availability bias, and confirmation bias. Each can subtly but decisively shape diagnostic judgement, often without the clinician’s awareness.

Common Biases

Anchoring bias occurs when a clinician relies excessively on the first piece of information received (ie, the anchor) when forming a judgement, while minimising or ignoring later and more relevant data. This first impression can influence subsequent assessments and treatments, particularly when the original anchor is incorrect.

Availability bias involves basing decisions on information that is most recent or most easily retrieved in the physician’s memory, not on the most clinically relevant information.

Confirmation bias refers to the tendency to seek out or preferentially value data that support an initial diagnostic hypothesis, while dismissing evidence that suggests alternative diagnoses.

A recent study confirmed the influence of anchoring bias on diagnostic decision-making among both general practitioners and specialists. The study included 54 practising physicians from the Spanish healthcare system, including primary care physicians and neurologists.

Participants were presented with a clinical vignette that was randomly assigned in one of two versions. In one version, the patient explicitly expressed concern about a specific serious disease. In the other, no particular suspicion was mentioned. After reading the vignette, physicians were asked to indicate the most likely diagnosis and which diagnostic tests they would request.

The only difference between the two vignettes was this initial piece of information, which was designed to assess the anchoring effect on clinical decisions.

The authors of the study noted that the nature of the information provided to the physician significantly influences diagnostic decisions. Specifically, the first information communicated by the patient, whether or not a serious suspicion is mentioned, largely determines the final diagnosis, which is consistent with the anchoring bias described in the literature.

This finding is consistent with the results from previous research showing that healthcare professionals tend to base decisions on their initial impression, even when more precise or relevant information becomes available later.

The authors concluded that the patient’s initial clue anchor themselves to it and direct their diagnosis toward that disease more frequently than those who evaluate the same case without such a clue.

Medical specialty emerges as a relevant factor in how initial information is processed. According to the study, when an anchoring signal is present, specialists tend to follow it more closely than general practitioners.

The authors suggested that this may be explained, at least in part, by differences in clinical approach. The tendency of specialists to rely on cognitive shortcuts developed through experience could make them more prone to anchoring on their initial impression.

The findings highlight the importance of addressing cognitive biases during medical training and in routine clinical practice. Strategies such as training in reflective clinical reasoning and the use of verification protocols, including diagnostic checklists or the systematic question “What else could it be?” force clinicians to reassess their hypotheses in light of new information.

The study also found that a physician’s sex does not influence the likelihood of anchoring on an initial diagnostic impression, suggesting that interventions should be directed at all clinicians equally. In addition, there was no strong evidence that clinical experience protects against anchoring bias. This reinforces the need for educational and organisational measures for both physicians in training and experienced practitioners.

This story was translated from El Medico Interactivo, part of the Medscape Professional Network.