title: Emergency department occupancy ratio is associated with increased early mortality.
abstract: BACKGROUND
  To measure emergency department (ED) crowding, the emergency department occupancy ratio (EDOR) was introduced.
  
  
  OBJECTIVE
  Our aim was to determine whether the EDOR is associated with mortality in adult patients who visited the study hospital ED.
  
  
  METHODS
  We reviewed data on all patients who visited the ED of an urban tertiary academic hospital in Korea for 2 consecutive years. The EDOR is defined by the total number of patients in the ED divided by the number of licensed ED beds. We tested the association between the EDOR (quartile) and each outcome using a multivariable logistic regression analysis adjusted for potential confounders: age, sex, emergency medical services transport, transferred case, weekend visit, shift, triage acuity, visit cause of injury, operation, vital signs, intensive care unit or ward admission, and ED length of stay (quartile). The main outcome measures were survival status at discharge and at 1-7 days.
  
  
  RESULTS
  A total of 54,410 adult patients were enrolled. The EDOR ranged from 0.41 to 2.31 and the median was 1.24. On multivariable analyses, in comparison with the lowest (first) quartile, the highest (fourth) quartile of the EDOR was associated with 1-day mortality (adjusted odds ratio [OR] = 1.42; 95% confidence interval [CI] 1.08-1.88), 2-day mortality (adjusted OR = 1.31; 95% CI 1.04-1.67), and 3-day mortality (adjusted OR = 1.27; 95% CI 1.02-1.58). The EDOR was not significantly associated with 4- to 7-day mortalities and overall mortality at discharge.
  
  
  CONCLUSIONS
  The EDOR is associated with increased 1- to 3-day mortality even after controlling for potential confounders.
authors.affiliation: Department of Emergency Medicine, Research Institute of Clinical Medicine of Chonbuk National University and Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Sion
authors.initials: S
authors.lastname: Jo
authors.affiliation: Department of Emergency Medicine, Research Institute of Clinical Medicine of Chonbuk National University and Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Jin
authors.affiliation: Department of Emergency Medicine, Research Institute of Clinical Medicine of Chonbuk National University and Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Jae Baek
authors.initials: JB
authors.lastname: Lee
authors.affiliation: Department of Emergency Medicine, Research Institute of Clinical Medicine of Chonbuk National University and Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Taeoh
authors.initials: T
authors.lastname: Jeong
authors.affiliation: Department of Emergency Medicine, Research Institute of Clinical Medicine of Chonbuk National University and Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Jaechol
authors.initials: J
authors.lastname: Yoon
authors.affiliation: National Cancer Control Institute, National Cancer Center, Goyang-si, Kyunggi-do, Korea.
authors.forename: Boyoung
authors.initials: B
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D001509:Bed Occupancy / Q000706:statistics & numerical data*; D003441:Crowding; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D017052:Hospital Mortality; D006784:Hospitals, Teaching / Q000706:statistics & numerical data; D006786:Hospitals, Urban / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D056910:Republic of Korea; D012189:Retrospective Studies
keywords: crowding; emergency department; emergency department occupancy ratio; poor outcome