Citation

Brown JB, Rosengart MR, Billiar TR, Peitzman AB, Sperry JL. J. Trauma Acute Care Surg. 2015; 80(1): 42-50.

Affiliation

Division of General Surgery and Trauma, Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213.

Copyright

(Copyright © 2015, Lippincott Williams and Wilkins)

DOI

10.1097/TA.0000000000000902

PMID

26517780

Abstract

BACKGROUND: Regionalized trauma care improves outcomes; however access to care is not uniform across the US. The objective was to evaluate whether geographic distribution of trauma centers correlates with injury mortality across state trauma systems.

METHODS: Level I/II trauma centers in the contiguous US were mapped. State-level age-adjusted injury fatality rates/100,000people were obtained and evaluated for spatial autocorrelation. Nearest neighbor ratios (NNR) were generated for each state. A NNR<1 indicates clustering, while NNR>1 indicates dispersion. NNR were tested for difference from random geographic distribution. Fatality rates and NNR were examined for correlation. Fatality rates were compared between states with trauma center clustering versus dispersion. Trauma center distribution and population density were evaluated. Spatial-lag regression determined the association between fatality rate and NNR, controlling for state-level demographics, population density, injury severity, trauma system resources, and socioeconomic factors.

RESULTS: Fatality rates were spatially autocorrelated (Moran's I=0.35, p<0.01). Nine states had a clustered pattern (median NNR 0.55, IQR 0.48-0.60), 22 had a dispersed pattern (median NNR 2.00, IQR 1.68-3.99), and 10 had a random pattern (median NNR 0.90, IQR 0.85-1.00) of trauma center distribution. Fatality rate and NNR were correlated (ρ=0.34, p=0.03). Clustered states had a lower median injury fatality rate compared to dispersed states (56.9 [IQR 46.5-58.9] versus 64.9 [IQR 52.5-77.1], p=0.04). Dispersed compared to clustered states had more counties without a trauma center that had higher population density than counties with a trauma center (5.7% versus 1.2%, p<0.01). Spatial-lag regression demonstrated fatality rates increased 0.02/100,000persons for each unit increase in NNR (p<0.01).

CONCLUSIONS: Geographic distribution of trauma centers correlates with injury mortality, with more clustered state trauma centers associated with lower fatality rates. This may be a result of access relative to population density. These results may have implications for trauma system planning and requires further study to investigate underlying mechanisms. LEVEL OF EVIDENCE: IV, ecological study.

Language: en