THE ROLE OF PREDECISIONAL INFORMATION DISTORTION IN MISDIAGNOSIS

Background:

Our inherent drive to formulate coherent judgements can lead to biased information processing: incoming evidence may be distorted to favour an emerging judgement, before a final decision is reached. This “predecisional information distortion” (PID) has also been found in medical diagnosis: physicians may interpret patient information in a way that favours their leading diagnostic hypothesis. The role of PID in misdiagnosis has not, however, been investigated. 

Purpose:

To assess the role of PID in misdiagnosis.

Method(s):

We constructed two patient cases, each with two competing diagnoses. One diagnosis was common and non-serious, the other rare and serious. Each case consisted of a brief patient description (demographics and health complaint) and several cues (symptoms, signs, and investigation results). Based on the available cues, the serious diagnosis could not be ruled out and warranted specialist referral. We presented 148 family physicians with one of the two patient cases, at random. After reading the patient description, physicians chose one of the two competing diagnoses. They then elicited further information: cues were arranged as labelled buttons on an information board that participants could click to reveal the answer. Each time a cue was revealed, participants evaluated it in relation to each competing diagnosis (0=“no support” to 10=”strong support”) and updated their diagnostic choice. When they felt ready, they made their final choice of diagnosis. We measured PID against the cue evaluations of a control group, and assessed its contribution to the final diagnosis via mediation analysis. 

Result(s):

Initial choice of diagnosis (non-serious vs. serious) predicted final choice (OR=4.78, P<0.001). Magnitude and direction of PID fully mediated this relationship: an initial non-serious diagnosis was associated with PID to support it, which in turn increased the odds of a non-serious final diagnosis. Final diagnosis predicted management: most physicians who provided a non-serious final diagnosis did not refer the patient (70%), whilst only 3% of those who provided a serious final diagnosis failed to refer. We identified no differences in the number of cues elicited by physicians who selected a non-serious vs. a serious final diagnosis.

Conclusion(s):

Our findings shed light on some of the cognitive causes of diagnostic error that can impact patients. Initial diagnostic hypotheses are important, but the interpretation of subsequent information may be more so.