title: Ranking hospitals according to acute myocardial infarction mortality: should transfers be included?
abstract: OBJECTIVE
  The objective of this population-based observational cohort study was to estimate the extent to which the inclusion/exclusion of transferred patients with acute myocardial infarction (AMI) impacts on hospital performance rankings.
  
  
  METHODS
  The authors studied 91,633 adult patients admitted to 116 acute care hospitals in Quebec, Canada, with a primary diagnosis of AMI between 1992 and 1999.
  
  
  METHODS
  Hospital performance ranks, based on 30-day AMI mortality rates, were estimated with hierarchical models and compared using 3 different methods for handling transferred patients (exclude all transfers; include transfers and assign outcome to the referring hospital; include transfers and assign outcome to the receiving hospital). The explanatory variable of interest was the hospital to which the patient's outcome was attributed.
  
  
  RESULTS
  Using the 3 methods, 4 hospitals were ranked "best performers" once, and 1 hospital ranked among the best in 2 of the 3 analyses performed. Nine hospitals were ranked "worst performers" at least once (4 of which ranked among the "worst" once only, 2 ranked among the "worst" twice, and 3 were consistently ranked "worst performers" in all analyses). There was significant variation in mortality rates among hospitals, and the difference in the rates between the highest and lowest ranking hospitals exceeded the clinically relevant benchmark of 1%.
  
  
  CONCLUSIONS
  Performance evaluation studies that compare hospital mortality rates typically exclude transferred patients. However, methods used to deal with AMI patient transfers influenced hospital ranks when comparing 30-day mortality rates. Excluding transfers may lead to an inaccurate depiction of the quality of healthcare services in regionalized healthcare systems that call for the timely interhospital transfer of patients with AMI.
authors.affiliation: Division of Clinical Epidemiology, Royal Victoria Hospital, McGill University Health Center, 687 Pine Avenue West, Montreal, Quebec, Canada. mylene.kossein@inspq.qc.ca
authors.forename: Mylène
authors.initials: M
authors.lastname: Kosseim
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Mayo
authors.forename: Susan
authors.initials: S
authors.lastname: Scott
authors.forename: James A
authors.initials: JA
authors.lastname: Hanley
authors.forename: James
authors.initials: J
authors.lastname: Brophy
authors.forename: Bruno
authors.initials: B
authors.lastname: Gagnon
authors.forename: Louise
authors.initials: L
authors.lastname: Pilote
mesh_terms: D000368:Aged; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality*; D010360:Patient Transfer / Q000706:statistics & numerical data*; D019984:Quality Indicators, Health Care / Q000458:organization & administration*