Case-control study to investigate variables associated with incidents and adverse events in the emergency department

Emerg Med Australas. 2017 Apr;29(2):149-157. doi: 10.1111/1742-6723.12736. Epub 2017 Jan 24.


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).

Conclusion: 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.

Keywords: diagnostic error; drug-related side-effects and adverse drug reaction; emergency service hospital; human; medical error.

MeSH terms

  • Adult
  • Aged
  • Case-Control Studies
  • Diagnostic Errors / statistics & numerical data
  • Diagnostic Errors / trends*
  • Drug-Related Side Effects and Adverse Reactions
  • Emergency Service, Hospital / organization & administration
  • Emergency Service, Hospital / statistics & numerical data*
  • Female
  • Humans
  • Logistic Models
  • Male
  • Medication Errors / statistics & numerical data
  • Medication Errors / trends*
  • Middle Aged
  • Multivariate Analysis
  • Odds Ratio