title: Emergency department 'undercrowding' is associated with decreased waiting times.
abstract: OBJECTIVE
  To evaluate the effect of a sudden and sustained decrease in patient presentations on waiting times and other measures of workload and flow following the opening of a large, greenfields ED adjacent to our own.
  
  
  METHODS
  A descriptive study involving all patients presenting to a private urban district hospital ED for two 60 day periods, immediately before and after the opening of the tertiary hospital ED. Changes in median waiting time, case-mix distribution, method of arrival, total admissions and total waiting time were compared pre-opening and post-opening. Non-normally distributed variables were analysed using Mann-Whitney U-tests. Categorical variables were compared using χ(2) analyses.
  
  
  RESULTS
  Patient presentations decreased by 28% with a parallel decline in median waiting time of 15 min (from 26 to 11 min) (P < 0.001). Total waiting time was approximately 29 h less per day in the post-opening period. Patient urgency by triage category did not change significantly (P = 0.316), whereas the proportion of presentations by ambulance decreased 15.9% (P = 0.048) and admission rate increased from 29.1% to 32.6% (P = 0.002).
  
  
  CONCLUSIONS
  Patient presentation numbers are strongly associated with and likely impact on median waiting time. Understanding that controlling demand can lead to significant benefits in patient processing, flow and overall patient perceived level of care and satisfaction is relevant to any discussion on ED overcrowding and the deleterious effects of access block.
authors.affiliation: Emergency Department, St John of God Murdoch Hospital, Perth, Western Australia, Australia.
authors.forename: Emogene S
authors.initials: ES
authors.lastname: Aldridge
authors.affiliation: Emergency Department, St John of God Murdoch Hospital, Perth, Western Australia, Australia.|University of Notre Dame Australia, Perth, Western Australia, Australia.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Rogers
authors.affiliation: Emergency Department, St John of God Murdoch Hospital, Perth, Western Australia, Australia.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Bailey
authors.affiliation: Emergency Department, St John of God Murdoch Hospital, Perth, Western Australia, Australia.
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Rogers
mesh_terms: D003441:Crowding; D003953:Diagnosis-Related Groups; D004636:Emergency Service, Hospital / Q000458:organization & administration*; D005260:Female; D006297:Health Services Accessibility; D016304:Hospitals, Private; D006786:Hospitals, Urban; D006801:Humans; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data; D013997:Time Factors; D014218:Triage; D014850:Waiting Lists; D014904:Western Australia; D016526:Workload
keywords: emergency department; health services accessibility; overcrowding; undercrowding