title: Comorbidities and prediction of length of hospital stay.
abstract: BACKGROUND
  Variability in length of stay (LOS) within Australian National Diagnosis Related Groups (AN-DRGs) reflects clinical heterogeneity in age, severity of illness, complications and comorbidities.
  
  
  OBJECTIVE
  To develop a clinically based score which measures patient morbidity and which will better predict LOS compared to existing methods.
  
  
  METHODS
  ICD-9-CM codes of diseases and procedures were allocated to one of 23 body system categories to calculate the body burden of disease (BBD) score. Evaluation of BBD in predicting LOS was performed using multiple regression and analysis of variance with a data set of 34,079 cases from 75 AN-DRGs from three Victorian hospitals.
  
  
  RESULTS
  Adding BBD and age improved prediction of LOS by 27.2% in AN-DRG version 1.0 and by 17.5% in AN-DRG version 3.1. When using average inlier LOS for AN-DRG, BBD and age improved prediction of LOS by 44.6% and by 14.8% in AN-DRG version 1.0 and version 3.1 respectively. Deaths were positively related to BBD.
  
  
  CONCLUSIONS
  BBD is a simple quantitative measure of extent of disease that improves current methods in accounting for variability in LOS.
authors.affiliation: Department of Nephrology, Austin and Repatriation Medical Centre, Melbourne, Vic.
authors.forename: C J
authors.initials: CJ
authors.lastname: Roe
authors.forename: E
authors.initials: E
authors.lastname: Kulinskaya
authors.forename: N
authors.initials: N
authors.lastname: Dodich
authors.forename: W R
authors.initials: WR
authors.lastname: Adam
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D015897:Comorbidity; D003953:Diagnosis-Related Groups; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data*; D012044:Regression Analysis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014739:Victoria / Q000453:epidemiology