title: The Canadian Adverse Events Study: the incidence of adverse events among hospital patients in Canada.
abstract: BACKGROUND
  Research into adverse events (AEs) has highlighted the need to improve patient safety. AEs are unintended injuries or complications resulting in death, disability or prolonged hospital stay that arise from health care management. We estimated the incidence of AEs among patients in Canadian acute care hospitals.
  
  
  METHODS
  We randomly selected 1 teaching, 1 large community and 2 small community hospitals in each of 5 provinces (British Columbia, Alberta, Ontario, Quebec and Nova Scotia) and reviewed a random sample of charts for nonpsychiatric, nonobstetric adult patients in each hospital for the fiscal year 2000. Trained reviewers screened all eligible charts, and physicians reviewed the positively screened charts to identify AEs and determine their preventability.
  
  
  RESULTS
  At least 1 screening criterion was identified in 1527 (40.8%) of 3745 charts. The physician reviewers identified AEs in 255 of the charts. After adjustment for the sampling strategy, the AE rate was 7.5 per 100 hospital admissions (95% confidence interval [CI] 5.7- 9.3). Among the patients with AEs, events judged to be preventable occurred in 36.9% (95% CI 32.0%-41.8%) and death in 20.8% (95% CI 7.8%-33.8%). Physician reviewers estimated that 1521 additional hospital days were associated with AEs. Although men and women experienced equal rates of AEs, patients who had AEs were significantly older than those who did not (mean age [and standard deviation] 64.9 [16.7] v. 62.0 [18.4] years; p = 0.016).
  
  
  CONCLUSIONS
  The overall incidence rate of AEs of 7.5% in our study suggests that, of the almost 2.5 million annual hospital admissions in Canada similar to the type studied, about 185 000 are associated with an AE and close to 70 000 of these are potentially preventable.
authors.affiliation: Department of Health Policy, Management and Evaluation, University of Toronto, McMurrich Building Room 2031, 12 Queen's Park Crescent West, Toronto, Ontario M5S 1A8, Canada. ross.baker@utoronto.ca
authors.forename: G Ross
authors.initials: GR
authors.lastname: Baker
authors.forename: Peter G
authors.initials: PG
authors.lastname: Norton
authors.forename: Virginia
authors.initials: V
authors.lastname: Flintoft
authors.forename: Régis
authors.initials: R
authors.lastname: Blais
authors.forename: Adalsteinn
authors.initials: A
authors.lastname: Brown
authors.forename: Jafna
authors.initials: J
authors.lastname: Cox
authors.forename: Ed
authors.initials: E
authors.lastname: Etchells
authors.forename: William A
authors.initials: WA
authors.lastname: Ghali
authors.forename: Philip
authors.initials: P
authors.lastname: Hébert
authors.forename: Sumit R
authors.initials: SR
authors.lastname: Majumdar
authors.forename: Maeve
authors.initials: M
authors.lastname: O'Beirne
authors.forename: Luz
authors.initials: L
authors.lastname: Palacios-Derflingher
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Reid
authors.forename: Sam
authors.initials: S
authors.lastname: Sheps
authors.forename: Robyn
authors.initials: R
authors.lastname: Tamblyn
mesh_terms: D002170:Canada / Q000453:epidemiology; D006276:Health Facility Size; D017052:Hospital Mortality; D006764:Hospitals, Community / Q000592:standards* / Q000706:statistics & numerical data; D006784:Hospitals, Teaching / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D007049:Iatrogenic Disease / Q000453:epidemiology* / Q000517:prevention & control; D015994:Incidence; D007902:Length of Stay / Q000706:statistics & numerical data; D008485:Medical Audit / Q000379:methods*; D019300:Medical Errors / Q000517:prevention & control / Q000706:statistics & numerical data*; D010343:Patient Admission / Q000706:statistics & numerical data; D010344:Patient Advocacy; D017751:Safety Management / Q000592:standards*