Challenging script concordance test reference standard by evidence: do judgments by emergency medicine consultants agree with likelihood ratios?

BACKGROUND: We aimed to compare the clinical judgments of a reference panel of emergency medicine academic physicians against evidence-based likelihood ratios (LRs) regarding the diagnostic value of selected clinical and paraclinical findings in the context of a script concordance test (SCT). FINDINGS: A SCT with six scenarios and five questions per scenario was developed. Subsequently, 15 emergency medicine attending physicians (reference panel) took the test and their judgments regarding the diagnostic value of those findings for given diseases were recorded. The LRs of the same findings for the same diseases were extracted from a series of published systematic reviews. Then, the reference panel judgments were compared to evidence-based LRs. To investigate the test-retest reliability, five participants took the test one month later, and the correlation of their first and second judgments were quantified using Spearman rank-order coefficient. In 22 out of 30 (73.3%) findings, the expert judgments were significantly different from the LRs. The differences included overestimation (30%), underestimation (30%), and judging the diagnostic value in an opposite direction (13.3%). Moreover, the score of a hypothetical test-taker was calculated to be 21.73 out of 30 if his/her answers were based on evidence-based LRs. The test showed an acceptable test-retest reliability coefficient (Spearman coefficient: 0.83). CONCLUSIONS: Although SCT is an interesting test to evaluate clinical decision-making in emergency medicine, our results raise concerns regarding whether the judgments of an expert panel are sufficiently valid as the reference standard for this test.