title: New ICD-10 version of the Charlson comorbidity index predicted in-hospital mortality.
abstract: OBJECTIVE
  The ICD-9-CM adaptation of the Charlson comorbidity score has been a valuable resource for health services researchers. With the transition into ICD-10 coding worldwide, an ICD-10 version of the Deyo adaptation was developed and validated using population-based hospital data from Victoria, Australia.
  
  
  METHODS
  The algorithm was translated from ICD-9-CM into ICD-10-AM (Australian modification) in a multistep process. After a mapping algorithm was used to develop an initial translation, these codes were manually examined by the coding experts and a general physician for face validity. Because the ICD-10 system is country specific, our goal was to keep many of the translated code at the three-digit level for generalizability of the new index.
  
  
  RESULTS
  There appears to be little difference in the distribution of the Charlson Index score between the two versions. A strong association between increasing index scores and mortality exists: the area under the ROC curve is 0.865 for the last year using the ICD-9-CM version and remains high, at 0.855, for the ICD-10 version.
  
  
  CONCLUSIONS
  This work represents the first rigorous adaptation of the Charlson comorbidity index for use with ICD-10 data. In comparison with a well-established ICD-9-CM coding algorithm, it yields closely similar prevalence and prognosis information by comorbidity category.
authors.affiliation: Victorian Department of Human Services, Level 18, 120 Spencer Street, Melbourne, 3000 Victoria, Australia. vijaya.sundararajan@dhs.vic.gov.au
authors.forename: Vijaya
authors.initials: V
authors.lastname: Sundararajan
authors.forename: Toni
authors.initials: T
authors.lastname: Henderson
authors.forename: Catherine
authors.initials: C
authors.lastname: Perry
authors.forename: Amanda
authors.initials: A
authors.lastname: Muggivan
authors.forename: Hude
authors.initials: H
authors.lastname: Quan
authors.forename: William A
authors.initials: WA
authors.lastname: Ghali
mesh_terms: D000465:Algorithms; D015897:Comorbidity; D017052:Hospital Mortality; D006801:Humans; D038801:International Classification of Diseases; D008875:Middle Aged; D012372:ROC Curve; D014739:Victoria