The ROC curves of each KTAS criterion (KTAS ≤1, KTAS ≤2, KTAS ≤3, KTAS ≤4, and KTAS ≤5). The AUC values of each criterion of KTAS (KTAS ≤1, KTAS ≤2, KTAS ≤3, KTAS ≤4, and KTAS ≤5) were 0.550, 0.745, 0.597, 0.501, and 0.50, respectively. The lines of KTAS ≤3 and KTAS ≤4 were so close that they seemed to overlap with each other. KTAS: Korean Triage and Acuity Scale, ROC: receiver operating characteristic, AUC: area under the curve.