title: Case-control study to investigate variables associated with incidents and adverse events in the emergency department.
abstract: OBJECTIVE
  To detect and analyse incidents (Is) and adverse events (AEs) in the ED. We hypothesised that I/AE are associated with patient load.
  
  
  METHODS
  We undertook a case-control study in a tertiary level hospital ED (from 1 April 2012 to 31 March 2013). Three percent of patients were randomly selected and screened for I/AEs. I/AEs were adjudicated by consensus of four FACEMs. Controls were matched to cases 2:1. Logistic regression was used to analyse the data.
  
  
  RESULTS
  We sampled 2167 patients. After exclusions, 217 I/AEs were detected and analysed. The I and AE rates were 6.0 and 4.1%, respectively. The serious AE rate was 0.8% and 30 day mortality was 0.1%. Diagnostic error occurred in 3.7% of all patients and adverse drug reactions in 2.5%. Seventy-seven percent of the I/AEs were judged preventable. ED occupancy of <35 patients was the reference group. Compared with this group, if 36-40 or 41-45 patients were in the ED, I/AEs were more likely to occur (odds ratio [OR] 2.37 [95% confidence interval (CI) 1.40-4.01, P < 0.0] and 1.8 [95% CI 1.03-3.15, P = 0.04], respectively) but not when there were >46 patients (OR 1.7, 95% CI 1.0-3.1). Higher hospital occupancy (90-99%) was a protective factor for sustaining an I/AE (OR 0.57, 95% CI 0.35-0.92, P = 0.02).
  
  
  CONCLUSIONS
  I/AEs are common in the ED and a large proportion is preventable. Strategies for prevention are required. The relationship with patient load needs further clarification, since our data suggests increased I/AE rates with higher occupancy but not highest occupancy.
authors.affiliation: Department of Emergency Medicine, Austin Health, Melbourne, Victoria, Australia.
authors.forename: Jamie
authors.initials: J
authors.lastname: Hendrie
authors.affiliation: Department of Emergency Medicine, Austin Health, Melbourne, Victoria, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Yeoh
authors.affiliation: Department of Emergency Medicine, Austin Health, Melbourne, Victoria, Australia.
authors.forename: Jo
authors.initials: J
authors.lastname: Richardson
authors.affiliation: Department of Emergency Medicine, Austin Health, Melbourne, Victoria, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Blunt
authors.affiliation: Clinical Information Analysis and Reporting, Austin Health, Melbourne, Victoria, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Davey
authors.affiliation: Department of Medicine, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: David
authors.identifier: http://orcid.org/0000-0002-8986-9997
authors.initials: D
authors.lastname: Taylor
authors.affiliation: Department of Physiotherapy, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Antony
authors.initials: A
authors.lastname: Ugoni
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003951:Diagnostic Errors / Q000706:statistics & numerical data / Q000639:trends*; D064420:Drug-Related Side Effects and Adverse Reactions; D004636:Emergency Service, Hospital / Q000458:organization & administration / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008508:Medication Errors / Q000706:statistics & numerical data / Q000639:trends*; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio
keywords: diagnostic error; drug-related side-effects and adverse drug reaction; emergency service hospital; human; medical error