Introduction: Multiple studies suggest that severely injured patients treated at trauma centers have a lower mortality compared to patients treated at non-trauma centers. In many trauma systems, a significant proportion of patients continue to be transported from the scene to a non-trauma center (undertriaged); only a fraction of these patients are subsequently transferred to trauma center care. Although previous analyses have attempted to examine the mortality associated with transfer and with undertriage, these studies were not population-based, and therefore potentially underestimated the mortality cost of undertriage at the system level. Methods: In this dissertation, we developed an algorithm to convert ICD-10 diagnosis codes to Injury Severity Score. This algorithm allowed us to utilize population-based data to examine the outcomes of all severely injured patients surviving to reach an emergency department in Ontario. We examined whether, among severely injured patients, transfer from a non-trauma center to a trauma center is associated with increased mortality compared to direct transport from the scene. In addition, we used an instrumental variable analysis to produce a population-based estimate of the mortality cost of undertriage in a subset of patients injured in motor vehicle collisions. Results: Patients requiring transfer to trauma center care have significantly higher mortality at 30 days than patients transported directly from the scene of injury (Odds ratio 1.24; 95% CI, 1.10-1.40). Among patients involved in motor vehicle collisions, only 45% were transported directly to a trauma center. In this subset of patients, those triaged directly to a trauma center had significantly lower mortality at 24 hours (Odds ratio 0.58, 95% CI 0.41-0.84) and 48 hours (Odds ratio 0.68, 95% CI 0.48-0.96) compared to undertriaged patients. There was a trend towards decreased mortality among patients triaged to a trauma center at 7 days and 30 days. Conclusions: Undertriage and transfer after major trauma are associated with substantial increase in mortality compared to direct transport to a trauma center. These data suggest a need to design strategies to improve access to trauma center care in Ontario.

Introduction: Multiple studies suggest that severely injured patients treated at trauma centers have a lower mortality compared to patients treated at non-trauma centers. In many trauma systems, a significant proportion of patients continue to be transported from the scene to a non-trauma center (undertriaged); only a fraction of these patients are subsequently transferred to trauma center care. Although previous analyses have attempted to examine the mortality associated with transfer and with undertriage, these studies were not population-based, and therefore potentially underestimated the mortality cost of undertriage at the system level. Methods: In this dissertation, we developed an algorithm to convert ICD-10 diagnosis codes to Injury Severity Score. This algorithm allowed us to utilize population-based data to examine the outcomes of all severely injured patients surviving to reach an emergency department in Ontario. We examined whether, among severely injured patients, transfer from a non-trauma center to a trauma center is associated with increased mortality compared to direct transport from the scene. In addition, we used an instrumental variable analysis to produce a population-based estimate of the mortality cost of undertriage in a subset of patients injured in motor vehicle collisions. Results: Patients requiring transfer to trauma center care have significantly higher mortality at 30 days than patients transported directly from the scene of injury (Odds ratio 1.24; 95% CI, 1.10-1.40). Among patients involved in motor vehicle collisions, only 45% were transported directly to a trauma center. In this subset of patients, those triaged directly to a trauma center had significantly lower mortality at 24 hours (Odds ratio 0.58, 95% CI 0.41-0.84) and 48 hours (Odds ratio 0.68, 95% CI 0.48-0.96) compared to undertriaged patients. There was a trend towards decreased mortality among patients triaged to a trauma center at 7 days and 30 days. Conclusions: Undertriage and transfer after major trauma are associated with substantial increase in mortality compared to direct transport to a trauma center. These data suggest a need to design strategies to improve access to trauma center care in Ontario.

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