Prehospital physiologic instability and in-hospital mortality among non-trauma patients with low-risk emergency department triage

Abstract

OBJECTIVES: Emergency department (ED) triage utilizes physiologic parameters obtained at ED presentation. However, physiologic abnormalities present in the prehospital phase may resolve before ED arrival. We evaluated whether prehospital physiologic instability was associated with mortality among patients classified as low risk at ED triage. METHODS: This retrospective multicenter cohort study included non-trauma adult patients transported by emergency medical services to 13 EDs in Seoul, Republic of Korea, from January 1, 2021, to December 31, 2024. The primary outcome was in-hospital mortality. The secondary outcome was a composite of in-hospital mortality or intensive care unit admission. Prehospital and ED triage physiologic status were quantified using the National Early Warning Score (NEWS) and categorized as low (0–4), medium (5–6 or any parameter scoree of 3), and high (≥7) risk groups. The primary analysis was restricted to patients classified as low risk at ED triage. RESULTS: Among 191,589 patients, 86,069 were classified as low clinical risk at ED triage. In this cohort, in-hospital mortality increased across prehospital NEWS categories from 1.2% in the low risk group to 2.4% in the medium risk group and 6.8% in the high risk group. Compared with low prehospital risk, medium and high prehospital risk were associated with increased odds of in-hospital mortality (adjusted odds ratio [AOR]: 1.93, 95% confidence interval [CI]: 1.67–2.22 and AOR: 4.10, 95% CI: 3.46–4.87, respectively). Similar patterns were observed for the composite outcome and across individual physiologic parameters. In the overall cohort, mortality increased stepwise across prehospital NEWS categories within each ED triage NEWS category. CONCLUSIONS: Prehospital physiologic instability was associated with increased in- hospital mortality among patients classified as low risk at ED triage. These findings suggest that normalization of physiologic parameters prior to ED arrival may not indicate resolution of risk.