Proportion of seriously injured patients admitted to hospitals in the US with a high annual injured patient volume: A metric of regionalized trauma care

BACKGROUND: Multiple regional trauma systems have been implemented over the past 3 decades to achieve the goal of regionalized care for injured patients. The American College of Surgeons Committee on Trauma (ACS-COT) advocates that seriously injured patients should be treated in designated Level I trauma centers that meet criteria including admitting more than 1,200 injured patients annually. Reliable measures are needed to evaluate the implementation of regionalized care nationally. The goal of this study was to measure the proportion of seriously injured patients treated at high injury-volume hospitals. STUDY DESIGN: We performed a retrospective observational study of injured patients hospitalized in the US during the years 1995 to 2003, drawn from the Nationwide Inpatient Sample. Hospitals were ranked in order of annual volume of injured patient admissions. A patient's severity of injury was calculated using ICD-9-based Injury Severity Score (ICISS). The principal measure was the proportion of seriously injured patients (ICISS <= 0.90) admitted to high-volume hospitals. RESULTS: Nine hundred fifteeen injured patients admitted per year is the empiric threshold for hospitals with a high injury volume. Only 7% of hospitals in the US meet this volume threshold. Sixty percent of seriously injured patients are treated in these high-volume hospitals; within the elder (age 65 years or older) subset, this percentage is lower. CONCLUSIONS: The proportion of seriously injured patients in high-volume hospitals is a functional metric that provides a practicable and comprehensive measure of regionalized trauma care in the US. Injured elder Americans have less access to experienced trauma hospitals.