Impact of anchoring bias in medical diagnostic decision-making: an experimental study

e202511072

Abstract

BACKGROUND // Cognitive biases, such as anchoring bias, significantly influence clinical decisions and contribute to up to 75% of diagnostic errors. Anchoring bias affects both general practitioners and specialists, although its impact may vary depending on the clinician’s experience and other factors. Biases are responsible for a substantial proportion of medical errors, highlighting the need to address them through interventions in training and clinical practice. The aim of this paper was to evaluate the impact of anchoring bias on diagnostic decision-making among general practitioners and specialists in the Spanish healthcare system.

METHODS // An experimental cross-sectional study using simulated clinical vignettes was carried out. Participants were randomly assigned to one of two experimental groups to examine how initial information influenced the final diagnosis. A total of fifty four active physicians were included, selected through convenience sampling. No dropouts were reported during the study. Participants were exposed to clinical vignettes in which the patient either mentioned or did not mention a possible serious illness. They were asked to formulate a diagnosis and request relevant diagnostic tests. The independent variable was the type of clinical vignette (mention of serious illness vs no specific suggestion). Dependent variables included the diagnosis made and the tests ordered. Covariates included gender, specialization, and medical experience. Logistic regression models were used to analyze the results.

RESULTS // The analysis revealed a significant relationship between the information provided and the final diagnosis (p<0.05), with a pseudo R-squared of 0.0825. Specialization showed a significant interaction with the independent variable (p=0.009), suggesting that specialists were more prone to anchoring bias than general practitioners. No moderating effect of gender or experience was found.

CONCLUSIONS // The findings highlight the importance of addressing cognitive biases —particularly anchoring bias— in medical training to improve diagnostic accuracy and reduce clinical errors.