title: Updating and validating the Charlson comorbidity index and score for risk adjustment in hospital discharge abstracts using data from 6 countries.
abstract: With advances in the effectiveness of treatment and disease management, the contribution of chronic comorbid diseases (comorbidities) found within the Charlson comorbidity index to mortality is likely to have changed since development of the index in 1984. The authors reevaluated the Charlson index and reassigned weights to each condition by identifying and following patients to observe mortality within 1 year after hospital discharge. They applied the updated index and weights to hospital discharge data from 6 countries and tested for their ability to predict in-hospital mortality. Compared with the original Charlson weights, weights generated from the Calgary, Alberta, Canada, data (2004) were 0 for 5 comorbidities, decreased for 3 comorbidities, increased for 4 comorbidities, and did not change for 5 comorbidities. The C statistics for discriminating in-hospital mortality between the new score generated from the 12 comorbidities and the Charlson score were 0.825 (new) and 0.808 (old), respectively, in Australian data (2008), 0.828 and 0.825 in Canadian data (2008), 0.878 and 0.882 in French data (2004), 0.727 and 0.723 in Japanese data (2008), 0.831 and 0.836 in New Zealand data (2008), and 0.869 and 0.876 in Swiss data (2008). The updated index of 12 comorbidities showed good-to-excellent discrimination in predicting in-hospital mortality in data from 6 countries and may be more appropriate for use with more recent administrative data.
authors.affiliation: Department of Community Health Sciences, Faculty of Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, Canada T2N 4Z6. hquan@ucalgary.ca
authors.forename: Hude
authors.initials: H
authors.lastname: Quan
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.forename: Chantal M
authors.initials: CM
authors.lastname: Couris
authors.forename: Kiyohide
authors.initials: K
authors.lastname: Fushimi
authors.forename: Patrick
authors.initials: P
authors.lastname: Graham
authors.forename: Phil
authors.initials: P
authors.lastname: Hider
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Januel
authors.forename: Vijaya
authors.initials: V
authors.lastname: Sundararajan
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001315:Australia / Q000453:epidemiology; D002170:Canada / Q000453:epidemiology; D015897:Comorbidity; D017281:Cost of Illness; D003953:Diagnosis-Related Groups / Q000706:statistics & numerical data; D005260:Female; D005602:France / Q000453:epidemiology; D017052:Hospital Mortality; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009026:Mortality; D009520:New Zealand / Q000453:epidemiology; D010351:Patient Discharge / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models; D020379:Risk Adjustment; D012737:Sex Factors; D013557:Switzerland / Q000453:epidemiology