A Model for Identifying and Ranking Need for Trauma Service in Nonmetropolitan Regions Based on Injury Risk and Access to Services Nadine Schuurman, PhD, Nathaniel Bell, MA, Morad S. Hameed, MD, MPH, FRCSC, FACS, and Richard Simons, MD, BChir, FRCSC, FACS, FRCS Background: Timely access to defin- itive trauma care has been shown to im- prove survival rates after severe injury. Unfortunately, despite development of so- phisticated trauma systems, prompt, de- finitive trauma care remains unavailable to over 50 million North Americans, par- ticularly in rural areas. Measures to quan- tify social and geographic isolation may provide important insights for the devel- opment of health policy aimed at reducing the burden of injury and improving access to trauma care in presently under serviced populations. Methods: Indices of social depriva- tion based on census data, and spatial analyses of access to trauma centers based on street network files were combined into a single index, the Population Isolation Vulnerability Amplifier (PIVA) to charac- terize vulnerability to trauma in socioeco- nomically and geographically diverse rural and urban communities across Brit- ish Columbia. Regions with a sufficient core population that are more than one hour travel time from existing services were ranked based on their level of socio- economic vulnerability. Results: Ten regions throughout the province were identified as most in need of trauma services based on population, iso- lation and vulnerability. Likewise, 10 com- munities were classified as some of the least isolated areas and were simultaneously clas- sified as least vulnerable populations in province. The model was verified using trauma services utilization data from the British Columbia Trauma Registry. These data indicate that including vulnerability in the model provided superior results to running the model based only on popula- tion and road travel time. Conclusions: Using the PIVA model we have shown that across Census Urban Areas there are wide variations in popu- lation dependence on and distances to ac- credited tertiary/district trauma centers throughout British Columbia. Many of the factors that influence access to defini- tive trauma care can be combined into a single quantifiable model that researchers in the health sector can use to predict where to place new services. The model can also be used to locate optimal loca- tions for any basket of health services. Key Words: Access to definitive care, Geographic information systems, Trauma services, Location model, Social vulnerability. J Trauma. 2008;65:54 – 62. S ocietal and geographic factors are known to have a substantial effect on mortality. 1 In the United States, a recent analysis of National Health Interview Survey data demonstrated significant disparities in potential years of life lost between strata of income, education, and race. These disparities were primarily attributable to ischemic heart disease, hypertension, cancers, type 2 diabetes, HIV and trauma. 2 Studies in the trauma literature have implicated indicators of socioeco- nomic status such as income, education of head of household, 3 household crowding, 4 social disorganization, acculturation, 5 birth weight, 6 ethnicity, and homelessness 7–9 as important de- terminants of injury risk. This relationship between socioeco- nomic status (SES) and injury may be overdetermined in the United States, where rates of violence are higher in the inner city, but recent research has confirmed the relationship. Birken et al. demonstrate that while childhood injury has declined during the past two decades, children in the lowest SES quintiles remain the most vulnerable. 10 A multilevel model analysis confirmed these results with the conclusion that lower SES was associated with greater rates of hospital- ization, whereas higher SES is linked to a greater number of sports injuries. 11 In some instances, these societal vulnerabilities to injury may be amplified by geographic ones, especially when access to definitive trauma care is delayed. A national inventory of trauma centers in the United States demonstrated improved trauma center availability overall in recent years, but also indicated tremendous geographic variability in number and resources of centers. 12 A follow-up study by the same group documented time of access to definitive care across the United States. Again tremendous variability in access was noted, with 47 million Americans having no access to level I or II trauma centers within an hour of injury. 13 Although similar studies have not yet been performed in Canada, geo- graphic variability and distances have left some communities especially vulnerable. Submitted for publication April 10, 2007. Accepted for publication October 9, 2007. Copyright © 2008 by Lippincott Williams & Wilkins From the Department of Geography, Simon Fraser University, Burnaby, British Columbia, Canada. Supported by Canadian Institutes of Health Research (CIHR) Grant No. 116338 and INJ-79997. Address for reprints: Nadine Schuurman, PhD, RCB 7123, Geography, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada; email: nadine@sfu.ca. DOI: 10.1097/TA.0b013e31815efe0e The Journal of TRAUMA  Injury, Infection, and Critical Care 54 July 2008