title: Predicting in-hospital mortality of traffic victims: A comparison between AIS-and ICD-9-CM-related injury severity scales when only ICD-9-CM is reported.
abstract: OBJECTIVE
  Injury severity scores are important in the context of developing European and national goals on traffic safety, health-care benchmarking and improving patient communication. Various severity scores are available and are mostly based on Abbreviated Injury Scale (AIS) or International Classification of Diseases (ICD). The aim of this paper is to compare the predictive value for in-hospital mortality between the various severity scores if only International Classification of Diseases, 9th revision, Clinical Modification ICD-9-CM is reported.
  
  
  METHODS
  To estimate severity scores based on the AIS lexicon, ICD-9-CM codes were converted with ICD Programmes for Injury Categorization (ICDPIC) and four AIS-based severity scores were derived: Maximum AIS (MaxAIS), Injury Severity Score (ISS), New Injury Severity Score (NISS) and Exponential Injury Severity Score (EISS). Based on ICD-9-CM, six severity scores were calculated. Determined by the number of injuries taken into account and the means by which survival risk ratios (SRRs) were calculated, four different approaches were used to calculate the ICD-9-based Injury Severity Scores (ICISS). The Trauma Mortality Prediction Model (TMPM) was calculated with the ICD-9-CM-based model averaged regression coefficients (MARC) for both the single worst injury and multiple injuries. Severity scores were compared via model discrimination and calibration. Model comparisons were performed separately for the severity scores based on the single worst injury and multiple injuries.
  
  
  RESULTS
  For ICD-9-based scales, estimation of area under the receiver operating characteristic curve (AUROC) ranges between 0.94 and 0.96, while AIS-based scales range between 0.72 and 0.76, respectively. The intercept in the calibration plots is not significantly different from 0 for MaxAIS, ICISS and TMPM.
  
  
  CONCLUSIONS
  When only ICD-9-CM codes are reported, ICD-9-CM-based severity scores perform better than severity scores based on the conversion to AIS.
authors.affiliation: Interuniversity Centre for Health Economics Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium. Electronic address: Griet.Van.Belleghem@vub.ac.be.
authors.forename: Griet
authors.initials: G
authors.lastname: Van Belleghem
authors.affiliation: Interuniversity Centre for Health Economics Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Devos
authors.affiliation: Interuniversity Centre for Health Economics Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
authors.forename: Liesbet
authors.initials: L
authors.lastname: De Wit
authors.affiliation: Emergency and Disaster Medicine, Department Emergency Medicine, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium.
authors.forename: Ives
authors.initials: I
authors.lastname: Hubloue
authors.affiliation: Emergency and Disaster Medicine, Department Emergency Medicine, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium.
authors.forename: Door
authors.initials: D
authors.lastname: Lauwaert
authors.affiliation: Medical Registration, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium.
authors.forename: Karen
authors.initials: K
authors.lastname: Pien
authors.affiliation: Interuniversity Centre for Health Economics Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Putman
mesh_terms: D015998:Abbreviated Injury Scale; D000063:Accidents, Traffic / Q000401:mortality* / Q000517:prevention & control / Q000706:statistics & numerical data; D001530:Belgium / Q000453:epidemiology; D019985:Benchmarking; D016208:Databases, Factual; D017052:Hospital Mortality; D006801:Humans; D015601:Injury Severity Score; D016015:Logistic Models; D011159:Population Surveillance; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D014193:Trauma Centers / Q000706:statistics & numerical data*; D015599:Trauma Severity Indices; D014947:Wounds and Injuries / Q000401:mortality* / Q000517:prevention & control
keywords: AIS; ICD-9; Multiple injuries; Single worst injury; TMPM; Traffic accident