Purpose: To assess the effectiveness of two modes of diagnostic support in family medicine: 1) suggestion of relevant diagnoses to consider at the beginning of the clinical encounter (“suggesting”) and 2) alert about diagnoses to exclude at the end of the encounter (“alerting”).
Method: We designed 9 detailed patient scenarios presenting one of 3 commonly misdiagnosed complaints, in a 3x3x3 factorial design: experimental condition (control, suggesting, alerting) x complaint (chest pain, abdominal pain, dyspnea) x case difficulty (easy, moderate, difficult). The study was powered to detect a 10% increase in diagnostic accuracy over control (N=297). The scenarios were presented to family physicians on computer over the Internet, while they were on the phone with a researcher. After reading some initial patient information on their screen, physicians could request further information in order to diagnose. The researcher selected the answer from a list and this was displayed to the physician. The suggesting list was presented after the patient’s main complaint and then disappeared (it could be recalled at will). The alerting list was presented only after physicians gave a diagnosis (they could change this following the alert).
Result: Current analyses based on 256 participants (86% of final sample) find a 5% overall increase in mean diagnostic accuracy with “suggesting” but no increase with “alerting” over control. In a logistic regression model that accounted for physician clustering and adjusted for case difficulty, the odds ratio of diagnosing correctly with “suggesting” was 1.3 (95% CI: 1.07–1.60, P=0.020). There was a significant correlation between the amount of information elicited and mean accuracy (Pearson r=0.40, P=<0.0001). There was no difference in the amount of information elicited between experimental conditions (P=0.67).
Conclusion: We found a modest effect of early suggestions of diagnoses to consider on family physicians’ accuracy, without an increase in the amount of information gathered. An appropriately developed computerized diagnostic support system, integrated with the patient record, that would activate automatically once the reason for encounter is entered, has the potential to improve diagnostic accuracy. In contrast, a system that monitors the information that the physician elicits during the encounter and alerts about further diagnoses to exclude is not likely to improve accuracy. It seems difficult to make physicians question their diagnosis once they have settled on it.