The use of the representativeness heuristic by psychiatrists in early psychosis diagnosis: a pilot study - data for sharing

<b>Objectives: </b>Heuristics allow clinicians to make efficient judgements under conditions of uncertainty but can also prejudice decision-making and contribute to clinical error. While other fields of medicine have been subject to analysis of these processes, psychiatry has largely been ignored. The aim of this study was to identify the use of heuristics - specifically, the representativeness heuristic - by psychiatrists in the diagnosis of Early Psychosis (EP). A further objective was to establish the effectiveness and feasibility of the methodology devised, given its novel application to this field. <b>Methods: </b>Fictional EP case vignettes were sent as an electronic questionnaire to members of RANZCP. The primary outcome measure was the difference between diagnostic likelihood ratings when irrelevant information designed to trigger the use of the representativeness heuristic was included.<b>Results: </b>There were 24 respondents. In 2 of 16 vignettes, irrelevant information significantly changed diagnostic likelihood ratings, suggesting use of the representativeness heuristic.<b>Conclusions: </b>Psychiatric doctors may use the representativeness heuristic when making diagnostic decisions in EP. This could have implications in terms of missed or misdiagnosis and subsequent access to appropriate treatments. Sufficiently powered research is required to further clarify the use of heuristics in psychiatric diagnosis. <br>