title: Accuracy of administrative data for assessing outcomes after knee replacement surgery.
abstract: OBJECTIVE
  To assess the accuracy of information in an administrative database (Canadian Institute for Health Information; CIHI) compared with the hospital record for patients undergoing knee replacement (KR).
  
  
  METHODS
  A stratified random sample of 185 KR recipients from 5 Ontario hospitals were chosen. Their hospital records and corresponding CIHI files were compared to assess percent complete agreement, false negative (FN) and false positive (FP) rates for demographic data, procedures, and diagnoses.
  
  
  RESULTS
  Of 185 records, 175 (95%) were reviewed. Percent complete agreement was greater than 94% for each of patient demographics and procedures (mean FN rates: 0%; mean FP rates: 0-5%). For comorbidities and complications, although mean percent complete agreement was high, and FP rates were low, mean FN rates were 63% for specific comorbid conditions and 70% for organ systems.
  
  
  CONCLUSIONS
  High FN rates have been found in documentation of comorbidities and in-hospital complications for CIHI data compared with the hospital record. Under-coding of comorbidities and in-hospital complications has potential implications for researchers using administrative databases.
authors.affiliation: Department of Medicine, Faculty of Medicine, University of Toronto, Ontario, Canada.
authors.forename: G A
authors.initials: GA
authors.lastname: Hawker
authors.forename: P C
authors.initials: PC
authors.lastname: Coyte
authors.forename: J G
authors.initials: JG
authors.lastname: Wright
authors.forename: J E
authors.initials: JE
authors.lastname: Paul
authors.forename: C
authors.initials: C
authors.lastname: Bombardier
mesh_terms: D015897:Comorbidity; D016208:Databases, Factual; D006753:Hospital Records; D006801:Humans; D007592:Joint Diseases / Q000150:complications / Q000601:surgery; D007720:Knee Prosthesis / Q000592:standards* / Q000706:statistics & numerical data*; D009864:Ontario; D017063:Outcome Assessment, Health Care; D010865:Pilot Projects; D011183:Postoperative Complications; D012042:Registries