Dispatch disparities: Neighborhood segregation as a predictor of EMS triage discordance among critically injured trauma patients.

Abstract

Timely emergency medical services (EMS) response is critical to improving survival after trauma. However, concordance between EMS dispatch level and on-scene patient acuity remains poorly understood. This study evaluated the association between racial and ethnic residential segregation and concordance between EMS response level and on-scene acuity among critically injured trauma patients. Using 2018-2022 National EMS Information System data, we analyzed trauma patient entries meeting CDC field triage criteria for transport to a trauma center. Concordance was defined as alignment between dispatch classification of response (emergent vs. nonemergent) and EMS providers' subsequent on-scene clinical assessment of acuity (critical/emergent vs. noncritical/low acuity). Racial and ethnic residential segregation at the ZIP Code level was measured using a multigroup dissimilarity index comparing neighborhood composition to county distribution. χ2 tests and multivariable logistic regression were used to assess the associations between segregation and under-triage, adjusting for region (Northeast, Midwest, South, West). Among 34.7 million critically injured patients over 5 years, 69% had concordant EMS responses, 6% were under-triaged, and 26% over-triaged. Concordance was highest in the Midwest (74%) and lowest in the Northeast (62%). Under-triage was most frequent in the West (10%) and least in the South (4%). Neighborhoods with medium and high segregation had twice the under-triage rates than low-segregation areas (8% and 7% vs. 4%, p<0.001). In adjusted analyses, medium and high segregation were 60% more likely to be associated with increased odds of under-triage (odds ratio: 1.61, 95% confidence: 1.60-1.61). This is the largest study to date demonstrating that racial and ethnic residential segregation was significantly associated with meaningfully and significantly increased risk of under-triage among critically injured trauma patients. Furthermore, structural inequities in neighborhood segregation may delay access to definitive trauma care. Equity-driven EMS policy reform, standardized dispatch protocols, and targeted training are needed to mitigate disparities in prehospital trauma response. (J Trauma Acute Care Surg 2026;00:000-000. Copyright © 2026 Wolters Kluwer Health, Inc. All rights reserved.). Prognostic and Epidemiological; Level IV.