Limitations of NEWS2 for predicting 48-hour emergency department revisits: a real-world retrospective cohort study

Early revisits to the emergency department (ED) are commonly used as a quality indicator and reflect challenges in discharge decision-making. Although the National Early Warning Score 2 (NEWS2) is widely used to detect clinical deterioration, its ability to predict early ED revisits after discharge remains unclear. We conducted a retrospective cohort study at a tertiary university hospital ED in Thailand from January 2019 to June 2022. Adult patients discharged from the ED were included. The primary outcome was an unplanned same-institution ED revisit within 48 h. Initial triage NEWS2 scores were analyzed, and predictive performance was assessed using overall area under the receiver operating characteristic curve (AUROC) and threshold-specific operating characteristics. Among 75,609 eligible index visits, 182 (0.24%) were followed by an unplanned ED revisit within 48 h. Initial triage NEWS2 showed no clinically useful discrimination (AUROC 0.54, 95% CI 0.49–0.58). A cut-off ≥ 2 provided modest sensitivity (58.2%) but low specificity (52.3%); higher cut-offs improved specificity at the expense of sensitivity. Positive predictive values were extremely low and likelihood ratios were close to 1. NEWS2, when used alone at initial ED triage, is insufficient for predicting unplanned 48-hour ED revisits. Early revisits may be influenced by multiple clinical, patient, and system-level factors beyond initial physiological abnormality. Multidimensional risk assessment tools may be more appropriate for supporting safe ED discharge decisions. TCTR20230816010, registered on 16 August 2023 (Thai Clinical Trials Registry, www.thaiclinicaltrials.org).