title: Prevalence of multimorbidity in medical inpatients.
abstract: OBJECTIVE
  To validate the estimates of the prevalence of multimorbidity based on administrative hospital discharge data, with medical records and chart reviews as benchmarks.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Medical division of a tertiary care teaching hospital.
  
  
  METHODS
  A total of 170 medical inpatients admitted from the emergency unit in January 2009.
  
  
  METHODS
  The prevalence of multimorbidity for three different definitions (≥2 diagnoses, ≥2 diagnoses from different ICD-10 chapters, and ≥2 medical conditions as defined by Charlson/Deyo) and three different data sources (administrative data, chart reviews, and medical records).
  
  
  RESULTS
  The prevalence of multimorbidity in medical inpatients derived from administrative data, chart reviews and medical records was very high and concurred for the different definitions of multimorbidity (≥2 diagnoses: 96.5%, 95.3%, and 92.9% [p = 0.32], ≥2 diagnoses from different ICD-10 chapters: 86.5%, 90.0%, and 85.9% [p = 0.46], and ≥2 medical conditions as defined by Charlson/Deyo: 48.2%, 50.0%, and 46.5% [p = 0.81]). The agreement of rating of multimorbidity for administrative data and chart reviews and administrative data and medical records was 94.1% and 93.0% (kappa statistics 0.47) for ≥2 diagnoses; 86.0% and 86.5% (kappa statistics 0.52) for ≥2 diagnoses from different ICD-10 chapters; and 82.9% and 85.3% (kappa statistics 0.69) for ≥2 medical conditions as defined by Charlson/Deyo.
  
  
  CONCLUSIONS
  Estimates of the prevalence of multimorbidity in medical inpatients based on administrative data, chart reviews and medical records were very high and congruent for the different definitions of multimorbidity. Agreement for rating multimorbidity based on the different data sources was moderate to good. Administrative hospital discharge data are a valid source for exploring the burden of multimorbidity in hospital settings.
authors.affiliation: Division of Internal Medicine, University Hospital Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Schneider
authors.forename: Vladimir
authors.initials: V
authors.lastname: Kaplan
authors.forename: Roksana
authors.initials: R
authors.lastname: Rodak
authors.forename: Edouard
authors.initials: E
authors.lastname: Battegay
authors.forename: Barbara
authors.initials: B
authors.lastname: Holzer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019468:Disease Management; D004630:Emergencies / Q000453:epidemiology*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006784:Hospitals, Teaching / Q000706:statistics & numerical data*; D006801:Humans; D007297:Inpatients; D008297:Male; D008875:Middle Aged; D009017:Morbidity / Q000639:trends; D015995:Prevalence; D012189:Retrospective Studies; D013557:Switzerland / Q000453:epidemiology; D055815:Young Adult