title: Trauma deaths in a mature urban trauma system: is "trimodal" distribution a valid concept?
abstract: BACKGROUND
  Trimodal distribution of trauma deaths, described more than 20 years ago, is still widely taught in the design of trauma systems. The purpose of this study was to examine the applicability of this trimodal distribution in a modern trauma system.
  
  
  METHODS
  A study of trauma registry and emergency medical services records of trauma deaths in the County of Los Angeles was conducted over a 3-year period. The times from injury to death were analyzed according to mechanism of injury and body area (head, chest, abdomen, extremities) with severe trauma (abbreviated injury score [AIS] >/= 4).
  
  
  RESULTS
  During the study period there were 4,151 trauma deaths. Penetrating trauma accounted for 50.0% of these deaths. The most commonly injured body area with critical trauma (AIS >/= 4) was the head (32.0%), followed by chest (20.8%), abdomen (11.5%), and extremities (1.8%). Time from injury to death was available in 2,944 of these trauma deaths. Overall, there were two distinct peaks of deaths: the first peak (50.2% of deaths) occurred within the first hour of injury. The second peak occurred 1 to 6 hours after admission (18.3% of deaths). Only 7.6% of deaths were late (>1 week), during the third peak of the classic trimodal distribution. Temporal distribution of deaths in penetrating trauma was very different from blunt trauma and did not follow the classic trimodal distribution. Other significant independent factors associated with time of death were chest AIS and head AIS. Temporal distribution of deaths as a result of severe head trauma did not follow any pattern and did not resemble classic trimodal distribution at all.
  
  
  CONCLUSIONS
  The classic "trimodal" distribution of deaths does not apply in our trauma system. Temporal distribution of deaths is influenced by the mechanism of injury, age of the patient, and body area with severe trauma. Knowledge of the time of distribution of deaths might help in allocating trauma resources and focusing research effort.
authors.affiliation: Division of Trauma and Critical Care, Department of Surgery, University of Southern California, Los Angeles, CA, USA.
authors.forename: Demetrios
authors.initials: D
authors.lastname: Demetriades
authors.forename: Brian
authors.initials: B
authors.lastname: Kimbrell
authors.forename: Ali
authors.initials: A
authors.lastname: Salim
authors.forename: George
authors.initials: G
authors.lastname: Velmahos
authors.forename: Peter
authors.initials: P
authors.lastname: Rhee
authors.forename: Christy
authors.initials: C
authors.lastname: Preston
authors.forename: Ginger
authors.initials: G
authors.lastname: Gruzinski
authors.forename: Linda
authors.initials: L
authors.lastname: Chan
mesh_terms: D000328:Adult; D006801:Humans; D016015:Logistic Models; D015141:Los Angeles / Q000453:epidemiology; D008875:Middle Aged; D013997:Time Factors; D014193:Trauma Centers / Q000706:statistics & numerical data*; D019037:Urban Health Services / Q000706:statistics & numerical data*; D014947:Wounds and Injuries / Q000145:classification / Q000401:mortality*; D014949:Wounds, Nonpenetrating / Q000145:classification / Q000401:mortality; D014950:Wounds, Penetrating / Q000145:classification / Q000401:mortality