摘要：Objectives. We sought to identify and characterize areas with high rates of major trauma events in 9 diverse cities and counties in the United States and Canada. Methods. We analyzed a prospective, population-based cohort of injured individuals evaluated by 163 emergency medical service agencies transporting patients to 177 hospitals across the study sites between December 2005 and April 2007. Locations of injuries were geocoded, aggregated by census tract, assessed for geospatial clustering, and matched to sociodemographic measures. Negative binomial models were used to evaluate population measures. Results. Emergency personnel evaluated 8786 major trauma patients, and data on 7326 of these patients were available for analysis. We identified 529 (13.7%) census tracts with a higher than expected incidence of major trauma events. In multivariable models, trauma events were associated with higher unemployment rates, larger percentages of non-White residents, smaller percentages of foreign-born residents, lower educational levels, smaller household sizes, younger age, and lower income levels. Conclusions. Major trauma events tend to cluster in census tracts with distinct population characteristics, suggesting that social and contextual factors may play a role in the occurrence of significant injury events. Injury is a major public health problem and one of the most common reasons for emergency department visits, health care expenses, morbidity, and mortality. 1 – 4 Although a growing body of literature has assessed individual-level injury factors and outcomes, relatively little research has evaluated how broader geographic, environmental, social, and cultural factors influence the occurrence of injury. Better understanding such macroscopic influences may improve health policy strategies for injury prevention, including community planning to reduce violence, defining the interplay between contextual and individual-level injury factors, efficient deployment of emergency medical service (EMS) resources, and more targeted public health efforts to reduce injury-related morbidity and mortality. Geographic information systems (GIS) analysis has been suggested as a novel tool in evaluating such geospatial and contextual components of injury events, 5 – 7 yet the number of GIS-based injury studies remains relatively sparse. Injury disproportionately affects individuals in certain racial, ethnic, and socioeconomic groups. 8 – 10 However, whether such differences function through individual-level mechanisms or are indicative of larger societal and environmental influences is unknown. Previous geospatial injury studies evaluated intentional injury (i.e., assault) 11 – 13 and violent crime 14 rates, falls among the elderly, 7 pedestrian injuries, 15 , 16 and trauma system patients. 17 These studies suggested that the locations where injuries occur are not random and that certain environmental (e.g., density of alcohol outlets), demographic, socioeconomic (e.g., poverty), and racial/ethnic factors, as well as time of day, are associated with higher injury and crime rates. However, previous research has been limited to single geographic areas, patients with certain mechanisms of injury, and hospitalized patients. 7 , 11 – 17 It remains unclear whether similar geospatial clustering exists among patients affected by additional injury mechanisms across diverse regions and communities and whether specific environmental and sociocultural factors can reliably identify high-risk populations. We sought to identify geospatial clusters of major trauma patients accessing 911 emergency services and to characterize socioeconomic, cultural, and demographic population measures in such locations across 9 diverse North American sites. These sites were Birmingham, Alabama; Dallas, Texas; Milwaukee, Wisconsin; Pittsburgh, Pennsylvania; Portland, Oregon; King County, Washington; Ottawa, Ontario; Toronto, Ontario; and Vancouver, British Columbia. Our overall aim was to combine both geospatial and population information to evaluate the contextual basis and broader social determinants of serious injury.
