title: The effect of hospital occupancy on emergency department length of stay and patient disposition.
abstract: Emergency department (ED) overcrowding is a common problem. Despite a widespread belief that low hospital bed availability contributes to ED overcrowding, there are few data demonstrating this effect.
  
  
  OBJECTIVE
  To identify the effect of hospital occupancy on ED length of stay for admitted patients and patient disposition.
  
  
  METHODS
  This was an observational study design using administrative data at a 500-bed acute care teaching hospital. All patients presenting to the ED between April 1993 and June 1999 were included in the study. The predictor variable was daily hospital occupancy. Outcome measures included daily ED length of stay for admitted patients, daily consultation rate, and daily admission rate. The models controlled for the average daily age of ED patients and the average daily "arrival density" index, which adjusts for patient volume and clustering of patient arrivals.
  
  
  RESULTS
  The average hospital occupancy was 89.7%. On average 155 patients visited the ED daily; 21% were referred to hospital physicians and 19% were admitted. The median ED length of stay for admitted patients was 5 hours 54 minutes (interquartile range 5 hr 12 min to 6 hr 42 min). Daily ED length of stay for admitted patients increased 18 minutes (95% CI = 12 to 24) when there was an absolute increase in occupancy of 10%. The ED length of stay appeared to increase extensively when hospital occupancy exceeded a threshold of 90%. Consultation and admission rates were not influenced by hospital occupancy.
  
  
  CONCLUSIONS
  Increased hospital occupancy is strongly associated with ED length of stay for admitted patients. Increasing hospital bed availability might reduce ED overcrowding.
authors.affiliation: Departments of Medicine, University of Ottawa, Ottawa, Ontario, Canada. aforster@ohri.ca
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Forster
authors.forename: Ian
authors.initials: I
authors.lastname: Stiell
authors.forename: George
authors.initials: G
authors.lastname: Wells
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Lee
authors.forename: Carl
authors.initials: C
authors.lastname: van Walraven
mesh_terms: D001509:Bed Occupancy / Q000706:statistics & numerical data*; D019992:Databases as Topic; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data*; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D010343:Patient Admission / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D013997:Time Factors