Using geographic information systems to map trauma center accessibility for gunshot wound victims in Chicago

Background/Purpose: Over a decade of research has demonstrated that specialized trauma centers improve survival from serious injury. However, the distribution of trauma centers is not uniform, with many areas of the country being poorly covered and suffering worse mortality rates for equivalent injury severity, particularly in rural areas. We hypothesized that trauma center access disparities exist even in urban areas, and sought to demonstrate disparities in access to definitive care for gunshot wounds (GSWs) in Chicago. Methods: Scene address data from the Illinois State Trauma Registry from 1999-2009 was utilized to geocode all GSWs that presented to trauma centers in Chicago during the study period. GSW frequency was mapped using geographic regression with ArcGIS 10.0 to create a population weighted relative risk using U.S. Census demographic data. Finally, accessibility scores were calculated using modified FCA 2 Step methodology and Network Analyst-estimated 30 minute drive time to the nearest trauma center to identify areas of limited access and higher need. Results: A total of 11,744 GSWs were geocoded. 48.9% of the city of Chicago and 36.1% of the population reside in census tracts with poor accessibility to a trauma center. 23.3% of the most at-risk population resides in these less-accessible areas, and 59.5% of the total African American population lives in areas with low accessibility, regardless of risk. Conclusions: We found that risk of GSWs did not correlate perfectly with accessibility to trauma centers. Given the frequent need for prompt surgical intervention for GSWs, this may contribute to location-based outcome disparities.