Increasing emergency department presentations stress the need for accurate triage systems to allocate resources efficiently. The current complaint-based triage approach has been criticized for its complexity and inconsistencies in assigning patients to appropriate acuity groups. The Modified Early Warning Score (MEWS) has been proposed as a potential alternative, given its ability to identify patients at high risk of deterioration. In a recent study, MEWS outperformed the Netherlands Triage System (NTS) in recognizing patients needing urgent care. This study aims to improve emergency triage by determining the characteristics of patients that are misclassified by MEWS and/or NTS.