The effect of clinical history on accuracy of electrocardiograph interpretation among doctors working in emergency departments

OBJECTIVE: To investigate whether bias in clinical history affects accuracy of electrocardiograph (ECG) interpretation among doctors working in emergency departments. DESIGN AND SETTING: Observational study conducted at four teaching hospitals in Sydney from May to September 2011. PARTICIPANTS: Participants interpreted 30 ECGs representing 10 diagnoses. ECGs were provided with positively biased history (suggestive of the correct diagnosis), negatively biased history (suggestive of an alternative diagnosis) or no history. MAIN OUTCOME MEASURES: Accuracy of ECG interpretation, measured as a score out of 10 (for each category of clinical history) and as a percentage of correctly interpreted ECGs. RESULTS: Of 307 doctors who were sent a recruitment email for the study, 132 participated (43%). The overall mean accuracy of ECG interpretation was 52% (95% CI, 50%-53%). For junior doctors, mean accuracy was 42% (95% CI, 40%-44%); for senior doctors, it was 65% (95% CI, 62%-67%). In adjusted models, the mean predicted score for senior doctors provided with no history was 6.25 (95% CI, 5.90-6.62) with junior doctors obtaining mean scores 34% lower than senior doctors (95% CI, 29%-40%; P < 0.001). Compared with no history, positively biased history was associated with 42% higher mean scores (95% CI, 35%-49%; P < 0.001) and negatively biased history was associated with 34% lower mean scores (95% CI, 29%-39%; P < 0.001). CONCLUSION: Bias in clinical history significantly influenced the accuracy of ECG interpretation. Strategies that reduce the detrimental impact of cognitive bias and improved ECG training for doctors are recommended.