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System Performance

Measuring Time Spent in Emergency Departments


In Ontario, the following data is reported for how long patients spend in the emergency department:

  • The patient's wait time to first assessment by a doctor in the emergency department.
  • The length of stay in the emergency department for low-urgency patients who were not admitted to hospital; and high-urgency patients who were not admitted to hospital.
  • The length of stay in the emergency department for patients who were admitted to the hospital.

All hospitals in Canada must assign their priority levels to patients based on the five-level Canadian Triage and Acuity Scale (CTAS) developed by the Canadian Association of Emergency Physicians, from Level 1 – Resuscitation down to Level 5 – Non-urgent.

Target times are set by the province and based on clinical evidence, to improve patient access and outcomes. The higher the percentage of patients treated within the target time period, the better.

What is measured

How it is measured

Clinical description

Ontario's target time

Wait time to first assessment by a doctor in the emergency department for all patients

Average time waited (in hours)

Volume ( number of patients)

How long patients waited from checking in at triage or registration, to their first assessment by a doctor, nurse-practitioner or dentist in the emergency department. For all CTAS levels.

Not applicable

Length of stay in the emergency department for low-urgency patients not admitted to hospital

Average time spent (in hours)

Percentage of patients who finished their visit to emergency within Ontario's target time

Volume (number of patients)

How long low-urgency patients (e.g. sore throat or vomiting), as assessed by the emergency department, spent in emergency and were not admitted to hospital (sent home or to another facility such as long-term care).

Patient's visit to emergency finished within 4 hours before being sent home or to another facility

Length of stay in the emergency department for high-urgency patients not admitted to hospital

Average time spent (in hours)

Percentage of patients who finished their emergency visit within Ontario's target time

Volume (number of patients)

How long high-urgency patients (e.g. severe allergic reaction or overdose), as assessed by the emergency department, spent in emergency before being spent home or to another facility.

Patient's visit to emergency finished within 8 hours before being sent home or to another facility

Length of stay in the emergency department for all patients admitted to hospital

Average time spent (in hours)

Percentage of patients admitted to hospital from the emergency department within Ontario's target time

Volume (number of patients)

How long patients spent in the emergency department, and were then admitted to hospital (includes any time a patient may have waited in the emergency department for a bed to be available in the hospital).

Patient's visit to emergency finished, and they moved into a hospital bed, within 8 hours

Measurement Numbers Used for Time Spent in Emergency Departments

Data for time spent in the emergency department is reported using these measurement numbers:

  • The average number of hours patients spent in the emergency department; a lower number is better.
  • The percentage of patients whose visit to the emergency department finished within the Ontario target time, or the percentage of patients admitted to hospital from the emergency department within the Ontario target time. A higher percentage is better.

Data Sources for Time Spent in Emergency Departments

The data comes from the National Ambulatory Care Reporting System, Canadian Institute for Health Information. Data is provided by Access to Care, Cancer Care Ontario.

Parts of this material are based on data and information compiled and provided by the Canadian Institute for Health Information. However, the analyses, conclusions, opinions and statements expressed herein are those of the author, and not necessarily those of the Canadian Institute for Health Information.

Time Spent in Emergency Departments

How long patients waited for first assessment by a doctor in emergency, and length of stay for patients of varying stages and conditions.

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