Secondary Undertriage of Severely Injured Trauma Patients Across the US

BACKGROUND: Secondary triage is a critical mechanism through which severely injured patients presenting to lower-resource hospitals are transferred to high-resource trauma centers, and is associated with improved survival. We conducted a contemporary, nationally representative analysis to quantify the volume of severely injured patients not transferred to higher-level care and to identify predictors of non-transfer. STUDY DESIGN: Retrospective cohort study using the 2019 Nationwide Emergency Department Sample of all adult trauma patients with an Injury Severity Score (ISS) >15 who first presented to a Level III or non-trauma center (NTC). Primary outcome was non-transfer, defined as admission to the Level III or NTC from the ED. Multivariable generalized linear models were developed to determine patient- and hospital-level predictors of non-transfer. RESULTS: Among 146,816 encounters, 84,695 (58%) patients were not transferred, reflecting secondary undertriage. Independent patient predictors of non-transfer included increasing age (≥80 years aOR 1.68, 95% CI 1.43-1.97) and public insurance (Medicare aOR 1.76 (95% CI 1.54, 2.02), Medicaid aOR 1.44, (95% CI 1.27, 1.65)). Hospital-level predictors included Level III trauma designation (aOR 2.93, 95% CI 2.10, 4.08) and metropolitan location (aOR 5.21, 95% CI 3.43-7.92). These predictors persisted in sub-analysis of patients with ISS ≥ 25. CONCLUSION: 1 in 3 severely injured trauma patients in the US are first treated at level III or NTCs, of which over half are not transferred to higher level trauma centers. Hospital factors including metropolitan location and Level III designation were the strongest predictors of non-transfer. These findings support the development of inclusive state trauma systems, that incorporate all acute care hospitals - including NTCs - in trauma registries and regional quality improvement initiatives.