A model for spatiotemporal injury surveillance: Implications for the evolution of a trauma system

BACKGROUND Geographic variations in case volume have important implications for trauma system configuration and have been recognized for some time. However, temporal trends in these distributions have received relatively little attention. The aim of this study was to propose a model to facilitate the spatiotemporal surveillance of injuries, using Scotland as a case study. METHODS Retrospective analysis of 5 years (2009-2013) of trauma incident location data. We analyzed the study population as a whole, as well as predefined subgroups, such as those with abnormal physiologic signs. To leverage sufficient statistical power to detect temporal trends in rare events over short time periods and small spatial units, we used a geographically weighted regression model. RESULTS There were 509,725 incidents. There were increases in case volume in Glasgow, the central southern part of the country, the northern parts of the Highlands, the Northeast, and the Orkney and Shetland Islands. Statistically significant changes were mostly restricted to major cities. Decreases in the number of incidents were seen in the Hebrides, Western Scotland, Fife and Lothian, and the Borders. Statistically significant changes were seen mostly in Fife and Lothian, the West, some areas of the Borders, and in the Peterhead area. Subgroup analyses showed markedly different spatiotemporal patterns. CONCLUSIONS This project has demonstrated the feasibility of population-based spatiotemporal injury surveillance. Even over a relatively short period, the geographic distribution of where injuries occur may change, and different injuries present different spatiotemporal patterns. These findings have implications for health policy and service delivery. LEVEL OF EVIDENCE Epidemiologic study, level V.