title: Tree-based algorithm for prehospital triage of polytrauma patients.
abstract: BACKGROUND
  There is a need for better allocation of medical resources in polytrauma, by optimizing both the over and undertriage rates. The goal of this study is to provide a new working definition for polytrauma based on the prediction of the need for specialized trauma care.
  
  
  METHODS
  This is a prospective, observational study, performed in a specialized trauma center in Paris. All consecutive patients admitted for a trauma at a major trauma center in Paris were included in the study. The primary outcome was the need for specialized trauma care as defined by the North American consensus. The explanatory variables included basic variables collected on scene. The modeling approach relied on recursive partitioning based decision trees. Its prediction performance was evaluated both internally and externally on a validation cohort, and compared to the MGAP (Mechanism, Glasgow coma scale, Age and Arterial pressure) score.
  
  
  RESULTS
  1160 patients were included in the analysis over a 3-year period (2012-2014), out of which 41% needed specialized trauma care as defined by the recent US guidelines. The decision tree outperformed the MGAP and reached an area under the receiver operating characteristic curve of 0.82 [0.79-0.84]. This optimal decision rule was associated with a sensitivity of 0.94 [0.92-0.96], a specificity of 0.48 [0.44-0.52]. A conservative decision rule (refer to a trauma center all patient with a predicted probability ≥0.34) would result in an undertriage rate of 5.7% and an overtriage of 52.3% (respectively 7% and 64% in the validation cohort).
  
  
  CONCLUSIONS
  Our tree-based decision algorithm is a user-friendly and reliable alternative to the preexisting scores, which offers good performance to predict the need for specialized trauma care.
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: arnaud.follin@gmail.com.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Follin
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: jacqmin_s@yahoo.fr.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Jacqmin
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: chhorv@gmail.com.
authors.forename: Vibol
authors.initials: V
authors.lastname: Chhor
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: florence.bellenfant@aphp.fr.
authors.forename: Florence
authors.initials: F
authors.lastname: Bellenfant
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: segolene.robin@hotmail.fr.
authors.forename: Ségolène
authors.initials: S
authors.lastname: Robin
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: alain.guinvarch2015@gmail.com.
authors.forename: Alain
authors.initials: A
authors.lastname: Guinvarc'h
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: fthomas@live.fr.
authors.forename: Frank
authors.initials: F
authors.lastname: Thomas
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France; SAMU 92, Hôpital Raymond Poincare, Université de Versailles St Quentin, Garches, France. Electronic address: tloeb@invivo.edu.
authors.forename: Thomas
authors.initials: T
authors.lastname: Loeb
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France. Electronic address: jean.mantz@aphp.fr.
authors.forename: Jean
authors.initials: J
authors.lastname: Mantz
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Européen Georges Pompidou, Université Paris 5 Descartes, Sorbonne Paris Cite, Paris, France; Department of Anesthesia and Perioperative Care, San Francisco General Hospital and Trauma Center, University of California San Francisco, San Francisco, USA; Département de Biostatistique et Informatique Médicale, INSERM U1153, équipe ECSTRA, Hôpital Saint Louis, Université Paris Diderot, Sorbonne Paris Cite, Paris, France; Division of Biostatistics, School of Public Health, University of California Berkeley, Berkeley, USA. Electronic address: romainpirracchio@yahoo.fr.
authors.forename: Romain
authors.initials: R
authors.lastname: Pirracchio
mesh_terms: D000328:Adult; D000465:Algorithms; D003663:Decision Trees; D004632:Emergency Medical Services / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009104:Multiple Trauma / Q000175:diagnosis* / Q000628:therapy; D010297:Paris / Q000453:epidemiology; D011446:Prospective Studies; D011785:Quality Assurance, Health Care; D014193:Trauma Centers; D015599:Trauma Severity Indices; D014218:Triage / Q000379:methods*
keywords: Decision tree; Polytrauma; Recursive partitioning; Trauma care; Triage