title: The value of traditional vital signs, shock index, and age-based markers in predicting trauma mortality.
abstract: BACKGROUND
  Systolic blood pressure (SBP), heart rate (HR), and respiratory rate are poor predictors of trauma outcome. We postulate that HR/SBP (shock index [SI]) and novel new markers SI × age (SIA), SBP / age (BPAI), maximum HR (220 - age) - HR (minpulse [MP]), and HR / maximum HR (pulse max index [PMI]) are better predictors of 48-hour mortality compared with traditional vital signs.
  
  
  METHODS
  Data were extracted from the Trauma Audit and Research Network database. Exclusions included any head or spine injury and prehospital intubation or cardiac arrest. Area under receiver operator characteristic curve (AUROC) was determined for 48-hour mortality for all variables and age. A threshold for each marker was derived using the specificity (rule-in) cutoffs at both 90% and 95% from the receiver operator characteristic curve. Positive likelihood ratios were described for each marker's derived threshold.
  
  
  RESULTS
  Vital signs, markers, and age were all significantly associated with 48-hour mortality (p < 0.001). HR, SBP, and respiratory rate fared worst overall (AUROC = 0.69, 0.66, and 0.66, respectively). SIA, MP, PMI, BPAI, and SI were significantly (p < 0.05) better than age at predicting 48-hour mortality (AUROC = 0.79, 0.77, 0.77, 0.74, 0.73, and 0.68, respectively; AUROC for age = 0.68). Thresholds derived for these five markers were values 55 or greater, 44 or less, 70% or greater, 1.5 or less, and 0.9 or greater, respectively, each with a specificity of 95% for 48-hour mortality (positive likelihood ratios were 8.4, 6.1, 6.7, 6.6, and 7.5, respectively). The likelihood of death in 48 hours was 8.4 times more likely if SIA was greater than 55 than if it was lower.
  
  
  CONCLUSIONS
  Older age seems to be significantly associated with early mortality. Newer markers, especially those combining traditional vital signs with age (SIA, BPAI, MP, and PMI), may contribute to better trauma triage of patients with blunt injuries than traditional vital signs.
  
  
  METHODS
  Prognostic/epidemiologic study, level III.
authors.affiliation: Division of Emergency Medicine, University of Cape Town, Karl Bremer Hospital, Bellville, South Africa. stevan.bruijns@afjem.com
authors.forename: Stevan R
authors.initials: SR
authors.lastname: Bruijns
authors.forename: Henry R
authors.initials: HR
authors.lastname: Guly
authors.forename: Omar
authors.initials: O
authors.lastname: Bouamra
authors.forename: Fiona
authors.initials: F
authors.lastname: Lecky
authors.forename: Wallis A
authors.initials: WA
authors.lastname: Lee
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D016208:Databases, Factual; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D056152:Respiratory Rate / Q000502:physiology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012774:Shock, Traumatic / Q000401:mortality* / Q000503:physiopathology; D013997:Time Factors; D055986:Vital Signs; D014947:Wounds and Injuries / Q000401:mortality* / Q000503:physiopathology
chemical_list: D015415:Biomarkers