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Association Between Emergency Medical Service Agency Volume and Mortality in Trauma Patients


AUTHORS

Silver DS , Sperry JL , Beiriger J , Lu L , Guyette FX , Wisniewski S , Moore EE , Schreiber M , Joseph B , Wilson CT , Cotton B , Ostermayer D , Fox EE , Harbrecht BG , Patel M , Brown JB , . Annals of surgery. 2023 8 28; ().

ABSTRACT

OBJECTIVE: Evaluate the association of annual trauma patient volume on outcomes for emergency medical services (EMS) agencies.

SUMMARY BACKGROUND DATA: Regionalization of trauma care saves lives. The underlying concept driving this is a volume-outcome relationship. EMS are the entry point to the trauma system, yet it is unknown if a volume-outcome relationship exists for EMS.

METHODS: Retrospective analysis of prospective cohort including eight trauma centers and 20 EMS air medical and metropolitan ground transport agencies. Patients 18-90 years old with injury severity scores >9 transported from scene were included. Patient and agency-level risk-adjusted regression determined the association between EMS agency trauma patient volume and mortality.

RESULTS: 33,511 were included with a median EMS agency volume of 374 patients annually (IQR 90-580). Each 50-patient increase in EMS agency volume was associated with 5% decreased odds of 6-hour mortality (aOR 0.95; 95%CI 0.92-0.99, P=0.03) and 3% decreased odds of 24-hour mortality (aOR 0.97; 95%CI 0.95-0.99, P=0.04). Pre-specified subgroup analysis showed EMS agency volume was associated with reduced odds of mortality for patients with prehospital shock, requiring prehospital airway placement, undergoing air medical transport, and those with traumatic brain injury. Agency-level analysis demonstrated that high-volume (>374 patients/year) EMS agencies had a significantly lower risk-standardized 6-hour mortality rate than low-volume (<374 patients/year) EMS agencies (1.9% versus 4.8%, P<0.01).

CONCLUSIONS: A higher volume of trauma patients transported at the EMS agency-level is associated with improved early survival. Further investigation of this volume-outcome relationship is necessary to leverage quality improvement, benchmarking, and educational initiatives.



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