title: Comorbidity indices to predict mortality from Medicare data: results from the national registry of atrial fibrillation.
abstract: BACKGROUND
  By accounting for level of comorbidity, risk-adjustment models should quantify the risk of death. How accurately comorbidity indices predict risk of death in Medicare beneficiaries with atrial fibrillation is unclear.
  
  
  OBJECTIVE
  We sought to quantify how well 3 administrative-data based comorbidity indices (Deyo, Romano, and Elixhauser) predict mortality compared with a chart-review index.
  
  
  METHODS
  We undertook a retrospective cohort study using Medicare claim data (1995-1999) and medical record review.
  
  
  METHODS
  We studied Medicare beneficiaries (n = 2728; mean age = 77) with a common cardiac dysrhythmia, atrial fibrillation.
  
  
  METHODS
  The outcome was time to death with the accuracy of the comorbidity indices measured by the c-statistic.
  
  
  RESULTS
  Correlation between Deyo and Romano indices was strong, but weak between them and the other indices. Prevalence of many comorbidity conditions varied with different indices. Compared with demographic data alone (c = 0.64), all comorbidity indices predicted death significantly (P < 0.001) better: the c index was 0.76 for Deyo, 0.78 for Romano, 0.76 for Elixhauser, and 0.75 for medical record review. The 95% confidence intervals of the c-statistic for the 4 indices overlapped with one another. Key comorbidity conditions for death included metastatic cancer, neuropsychiatric disease, heart failure, and liver disease.
  
  
  CONCLUSIONS
  The predictive accuracy of 3 administrative-data based indices was similar and comparable with chart-review.
authors.affiliation: Division of General Medical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Elena
authors.initials: E
authors.lastname: Birman-Deych
authors.forename: Martha J
authors.initials: MJ
authors.lastname: Radford
authors.forename: David S
authors.initials: DS
authors.lastname: Nilasena
authors.forename: Brian F
authors.initials: BF
authors.lastname: Gage
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000401:mortality*; D015331:Cohort Studies; D015897:Comorbidity; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D006278:Medicare; D016016:Proportional Hazards Models; D012042:Registries; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014481:United States / Q000453:epidemiology