title: Initial validation of the International Crowding Measure in Emergency Departments (ICMED) to measure emergency department crowding.
abstract: BACKGROUND
  Emergency department (ED) crowding is recognised as a major public health problem. While there is agreement that ED crowding harms patients, there is less agreement about the best way to measure ED crowding. We have previously derived an eight-point measure of ED crowding by a formal consensus process, the International Crowding Measure in Emergency Departments (ICMED). We aimed to test the feasibility of collecting this measure in real time and to partially validate this measure.
  
  
  METHODS
  We conducted a cross-sectional study in four EDs in England. We conducted independent observations of the measure and compared these with senior clinician's perceptions of crowding and safety.
  
  
  RESULTS
  We obtained 84 measurements spread evenly across the four EDs. The measure was feasible to collect in real time except for the 'Left Before Being Seen' variable. Increasing numbers of violations of the measure were associated with increasing clinician concerns. The area under the receiver operating characteristic curve was 0.80 (95% CI 0.72 to 0.90) for predicting crowding and 0.74 (95% CI 0.60 to 0.89) for predicting danger. The optimal number of violations for predicting crowding was three, with a sensitivity of 91.2 (95% CI 85.1 to 97.2) and a specificity of 100.0 (92.9-100). The measure predicted clinician concerns better than individual variables such as occupancy.
  
  
  CONCLUSIONS
  The ICMED can easily be collected in multiple EDs with different information technology systems. The ICMED seems to predict clinician's concerns about crowding and safety well, but future work is required to validate this before it can be advocated for widespread use.
authors.affiliation: Emergency Department, Addenbrooke's Hospital Cambridge University Hospitals NHS Foundation Trust, Cambridge, Cambridgeshire, UK.
authors.forename: Adrian
authors.initials: A
authors.lastname: Boyle
authors.affiliation: Clinical School, Cambridge University, Cambridge, Cambridgeshire, UK.
authors.forename: James
authors.initials: J
authors.lastname: Coleman
authors.affiliation: Emergency Department, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, Cambridgeshire, UK.
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Sultan
authors.affiliation: Emergency Department, Peterborough and Stamford Hospitals NHS Foundation Hospitals Trust, Peterborough, UK.
authors.forename: Vijayasankar
authors.initials: V
authors.lastname: Dhakshinamoorthy
authors.affiliation: Emergency Department, Hinchingbrooke Healthcare NHS Trust, Huntingdon, UK.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: O'Keeffe
authors.affiliation: Clinical School, Cambridge University, Cambridge, Cambridgeshire, UK.
authors.forename: Pramin
authors.initials: P
authors.lastname: Raut
authors.affiliation: Engineering Design Centre, Cambridge University, Cambridge, Cambridgeshire, UK.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Beniuk
mesh_terms: D001291:Attitude of Health Personnel; D001509:Bed Occupancy / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D003441:Crowding; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D004739:England; D005240:Feasibility Studies; D006302:Health Services Research / Q000379:methods*; D006801:Humans; D012372:ROC Curve; D012449:Safety; D012680:Sensitivity and Specificity
keywords: emergency care systems, efficiency; emergency department management; management, emergency department management; systems