Context: The premise underlying regionalization of trauma care is that larger volumes of trauma patients cared for in fewer institutions will lead to improved outcomes. However, whether a relationship exists between institutional volume and trauma outcomes remains unknown.
Objective: To evaluate the association between trauma center volume and outcomes of trauma patients.
Design: Retrospective cohort study.
Setting: Thirty-one academic level I or level II trauma centers across the United States participating in the University Healthsystem Consortium Trauma Benchmarking Study.
Patients: Consecutive patients with penetrating abdominal injury (PAI; n = 478) discharged between November 1, 1997, and July 31, 1998, or with multisystem blunt trauma (minimum of head injury and lower-extremity long-bone fractures; n = 541) discharged between June 1 and December 31, 1998.
Main outcome measures: Inpatient mortality and hospital length of stay (LOS), comparing high-volume (>650 trauma admissions/y) and low-volume (</=650 admissions/y) centers.
Results: After multivariate adjustment for patient characteristics and injury severity, the relative odds of death was 0.02 (95% confidence interval [CI], 0.002-0.25) for patients with PAI admitted with shock to high-volume centers compared with low-volume centers. No benefit was evident in patients without shock (P =.50). The adjusted odds of death in patients with multisystem blunt trauma who presented with coma to a high-volume center was 0.49 (95% CI, 0.26-0.93) vs low-volume centers. No benefit was observed in patients without coma (P =.05). Additionally, a shorter LOS was observed in patients with PAI and New Injury Severity Scores of 16 or higher (difference in adjusted mean LOS, 1.6 days [95% CI, -1.5 to 4.7 days]) and in all patients with multisystem blunt trauma admitted to higher-volume centers (difference in adjusted mean LOS, 3.3 days [95% CI, 0.91-5.70 days]).
Conclusions: Our results indicate that a strong association exists between trauma center volume and outcomes, with significant improvements in mortality and LOS when volume exceeds 650 cases per year. These benefits are only evident in patients at high risk for adverse outcomes.