Table 1

International Crowding Measure in Emergency Departments (ICMED)

MeasureOperational definition
Input measures
1. Ability of ambulances to offload patientsAn ED is crowded when the 90th centile time between ambulance arrival and offload is greater than 15 min
2. Patients who leave without being seen or treated (LWBS)An ED is crowded when the number of patients who LWBS is greater than or equal to 5%
3. Time until triageAn ED is crowded when there is a delay greater than 5 min from patient arrival to begin their initial triage
Throughput measures
4. ED occupancy rateAn ED is crowded when the occupancy rate is greater than 100%
5. Patients’ total length of stay in the ED*An ED is crowded when the 90th centile patient's total length of stay is greater than 4 h.
6. Time until a physician first sees the patientAn ED is crowded when an emergent (one ortwo) patient waits longer than 30 min to be seen by a physician
Output measures
7. ED boarding time†An ED is crowded when less than 90% of patients have left the ED 2 h after the admission decision
8. Number of patients boarding in the ED‡Boarders are defined as admitted patients waiting to be placed in an inpatient bed. An ED is crowded when there is greater than 10% occupancy of boarders in the ED
  • *For example, in an ED with 50 patients inside, if more than five patients had been there longer than 4 h, then this would count as a violation.

  • †For example, in an ED with 10 patients who are waiting for admission, if more than one of these patients had waited longer than 2 h, then this would count as a violation.

  • ‡For example, in an ED with 50 patients inside, if more than five patients are waiting for admission, then this would count as a violation.

  • ED, emergency department.