BMJ Qual Saf 20:564-569 doi:10.1136/bmjqs.2009.034926
  • Original research

The association between a prolonged stay in the emergency department and adverse events in older patients admitted to hospital: a retrospective cohort study

  1. G Kovacs1
  1. 1Department of Emergency Medicine, Dalhousie University, Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia, Canada
  2. 2Department of Community Health & Epidemiology, Dalhousie University
  3. 3College of Pharmacy, Dalhousie University
  1. Correspondence to Stacy Ackroyd-Stolarz, Canadian Patient Safety Institute/Canadian Institutes of Health Research Dr David Rippey Patient Safety Postdoctoral Fellow, Department of Emergency Medicine, Dalhousie University, Queen Elizabeth II Health Sciences Centre, Halifax Infirmary, Suite 355, 1796 Summer Street, Halifax, Nova Scotia, Canada; stacy.ackroyd{at}
  1. Contributors SA-S: responsible for conception and design of study, data acquisition, data analysis and interpretation, and wrote and revised the manuscript based on feedback from all coauthors. JRG, NJM and GK: contributed to the conception and design of study and interpretation of study results. All of the study authors had access to study data and take responsibility for the integrity of the data and accuracy of the data analysis. All of the authors have reviewed the manuscript and given approval for the final version.

  • Accepted 11 November 2009
  • Published Online First 5 January 2011


Objective Patient safety studies have identified older adults as a high-risk group for adverse events (AEs). As frequent users of the emergency department (ED), they are vulnerable to the negative consequences of ED crowding. The study objective was to determine whether a prolonged ED stay is associated with an increased risk for the occurrence of AEs for older patients admitted to hospital.

Methods This retrospective cohort study was conducted at the largest adult tertiary care facility in Atlantic Canada (1 July 2005–31 March 2006). All community-dwelling persons 65 years and older admitted to an acute inpatient unit from the ED were eligible. The exposure of interest was total length of stay (LOS) in the ED. The primary outcome was the occurrence of an AE in-hospital. AEs were identified from administrative diagnostic data using previously validated screening criteria.

Results The average age of 982 eligible participants was 77.8 years (SD 7.8). The majority (75.0%) experienced a prolonged ED LOS as defined by national guidelines. There was evidence of at least one AE in 140 (14.3%) records. After adjustment, for every hour spent in the ED, the odds of experiencing an AE in-hospital increased 3% (OR 1.03, 95% CI 1.004 to 1.05). Those with an AE had twice the hospital LOS (20.2 vs 9.8 days, p<0.00001).

Interpretation A prolonged ED stay for older admitted patients is associated with an increased risk of an in-hospital AE. The longer hospital LOS associated with AEs further reduces the availability of acute care beds, thus exacerbating ED crowding.


  • Funding Financial support for doctoral studies (SA-S) was received from the Canadian Institutes of Health Research (Ottawa, Ontario, Canada) Strategic Training Fellowship Program (Transdisciplinary Understanding and Training on Research-Primary Health Care (TUTOR-PHC)) and from the Nova Scotia Health Research Foundation (Halifax, Nova Scotia, Canada). The funding agencies did not play a role in the study design, data collection, analysis or interpretation.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Capital District Health Authority, Halifax, Nova Scotia, Canada.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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