title: A modified Elixhauser score for predicting in-hospital mortality in internal medicine admissions.
abstract: BACKGROUND
  In-hospital mortality (IHM) is an indicator of the quality of care provided. The two most widely used scores for predicting IHM by International Classification of Diseases (ICD) codes are the Elixhauser (EI) and the Charlson Comorbidity indexes. Our aim was to obtain new measures based on internal medicine ICD codes for the original EI, to detect risk for IHM.
  
  
  METHODS
  This single-center retrospective study included hospital admissions for any cause in the department of internal medicine between January 1, 2000, and December 31, 2013, recorded in the hospital database. The EI was calculated for evaluation of comorbidity, then we added age, gender and diagnosis of ischemic heart disease. IHM was our outcome. Only predictors positively associated with IHM were taken into consideration and the Sullivan's method was applied in order to modify the parameter estimates of the regression model into an index.
  
  
  RESULTS
  We analyzed 75,586 admissions (53.4% females) and mean age was 72.7±16.3years. IHM was 7.9% and mean score was 12.1±7.6. The points assigned to each condition ranged from 0 to 16, and the possible range of the score varied between 0 and 89. In our population the score ranged from 0 to 54, and it was higher in the deceased group. Receiver operating characteristic curve of the new score was 0.721 (95% CI 0.714-0.727, p<0.001).
  
  
  CONCLUSIONS
  In order to make prognostic assessment, the use of a score could be of help in targeting interventions in older adults, identifying subjects at high risk for IHM.
authors.affiliation: Department of Medical Sciences, Clinica Medica Unit, University of Ferrara, Italy. Electronic address: f.fabbian@ospfe.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Fabbian
authors.affiliation: Department of Medical Sciences, Clinica Medica Unit, University of Ferrara, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: De Giorgi
authors.affiliation: Center for Clinical Epidemiology, University of Ferrara, Ferrara, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Maietti
authors.affiliation: Department of Internal Medicine, Hospital of Ferrara, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Gallerani
authors.affiliation: Department of Internal Medicine, Hospital of Ferrara, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Pala
authors.affiliation: Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy.
authors.forename: Rosaria
authors.initials: R
authors.lastname: Cappadona
authors.affiliation: Department of Medical Sciences, Clinica Medica Unit, University of Ferrara, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Manfredini
authors.affiliation: SER - Epidemiological Department, Veneto Region, Padua, Italy.
authors.forename: Ugo
authors.initials: U
authors.lastname: Fedeli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D005260:Female; D017052:Hospital Mortality / Q000639:trends*; D006785:Hospitals, University; D006801:Humans; D007388:Internal Medicine; D038801:International Classification of Diseases; D007558:Italy; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data*; D011379:Prognosis; D019984:Quality Indicators, Health Care; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index
keywords: Comorbidity; In-hospital mortality; Internal medicine; International Classification of Diseases; Score