title: External factors and the incidence of severe trauma: time, date, season and moon.
abstract: BACKGROUND
  To detect whether external factors (time of day, day of week, month and season, lunar phases) influence incidence and outcome of severely injured trauma patients.
  
  
  METHODS
  A retrospective cohort analysis of the TraumaRegister DGU(®) (TR-DGU) was carried out over a period of 10 years (January 2002-December 2011). Data of 35,432 primary admitted patients from Germany with a severe trauma (Injury Severity Score (ISS) >15) were analysed in this study. For the outcome evaluation transferred patients were excluded as well as those who did not have a valid Revised Injury Severity Classification (RISC) prognostic score. The outcome analysis could be performed in 31,596 (89.2%) patients. Incidence, demographics and injury pattern were analysed. For outcome analysis the observed hospital mortality was compared with the expected prognosis.
  
  
  RESULTS
  Time of day was the factor that showed the highest variation in trauma incidence due to rush hours. Saturday was the day with the highest accident rate. Most accidents in the night happened on weekends. June and July were the months with the highest trauma rate with a large portion of two-wheel drivers. The days of year with the lowest trauma incidence rate were those between Christmas and New Year, and the highest rate was observed on May 1st. The outcome of the trauma patients was close to the prognosis in all investigated subgroups.
  
  
  CONCLUSIONS
  There are clear differences in incidence but not in outcome of the patients due to external factors.
authors.affiliation: Institute for Research in Operative Medicine (IFOM), Private University of Witten/Herdecke, Cologne, Germany.
authors.forename: Carolina I A
authors.initials: CI
authors.lastname: Pape-Köhler
authors.affiliation: Department of Orthopedics, Trauma and Sportsmedicine, Private University of Witten/Herdecke, Cologne-Merheim Medical Center, Cologne, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Simanski
authors.affiliation: AUC - Academy for Trauma Surgery (AUC), Berlin, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Nienaber
authors.affiliation: Institute for Research in Operative Medicine (IFOM), Private University of Witten/Herdecke, Cologne, Germany. Electronic address: rolf.lefering@uni-wh.de.
authors.forename: Rolf
authors.initials: R
authors.lastname: Lefering
mesh_terms: D000059:Accidents / Q000401:mortality / Q000706:statistics & numerical data*; D000328:Adult; D015331:Cohort Studies; D005260:Female; D005858:Germany / Q000453:epidemiology; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D015994:Incidence; D015601:Injury Severity Score; D008297:Male; D008875:Middle Aged; D016081:Moon; D009104:Multiple Trauma / Q000453:epidemiology* / Q000401:mortality; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D016019:Survival Analysis; D013997:Time Factors; D014193:Trauma Centers / Q000706:statistics & numerical data*; D016896:Treatment Outcome
keywords: Date; Epidemiology; External factors; Incidence; Outcome; Registry; Season; Trauma and injuries