Seasonal and time of day variation related to the daily incidence of major traumatic injury in a large US city

Abstract

Background Trauma is a major burden on the healthcare system of Chicago with greater than 9000 major injuries annually. If fluctuations in trauma could be predicted by ecologic variables, more effective allocation of hospital and pre-hospital resources could be achieved. Methods The Illinois Trauma Registry was retrospectively analyzed to investigate several group-level factors potentially related to the incidence of major traumatic injury from 1999 through 2009. Univariate and multivariate linear regression analyses evaluated the effects of weekday, maximum daily temperature, rain, snow, and major holidays on daily trauma incidence. Results A total of 107,546 trauma admissions occurred during the study period and were included in the analysis. Time of day (peak hours 22:00 to 02:00, odds ratio (OR) 2.66), weekday (OR 1.27 for Friday and Saturday), mean daily temperature, rain, snow, and four holidays were found to be associated with differential risks of trauma. Martin Luther King, Jr. day was protective, with OR 0.86; Independence Day, Halloween, and New Years Eve all experienced higher trauma burdens than monthly, weather-weighted averages. Conclusions Several ecologic variables were found to be associated with the incidence of traumatic injury in Chicago, accounting for 40.0% of the daily variance. These results will help inform staffing decisions.