Ontario Wait Times

Time Spent in the ER - About the Data

The 128 hospitals providing ER wait time data on this website have supplied and verified it as part of the Ministry of Health and Long-Term Care’s funding conditions for receiving money to pay for additional procedures and tests.

Hospitals submit the data electronically, using Level 1 NARCS (National Ambulatory Care Reporting System), CIHI to Cancer Care Ontario’s Access To Care (CCO-ATC) Informatics Office. The data on this site is one month old. The Ministry of Health and Long-Term Care updates it on the last Thursday of every month. It is the most current and accurate information available on time spent in ER in Ontario.

Please note : The baseline (April 2008) results have been updated to address a data quality issue that occurred in an organization and that has been resolved. The ministry’s Data Certification Council approved this change request in September 2009.


What is being measured?

For ER visits, Ontario measures the wait time from the time when the patient is triaged or registered in the ER (which ever comes first, depending on the hospital’s process) until the time when the patient leaves the ER (admission to an inpatient bed at the hospital or discharge).

Types of Hospitals

Teaching Hospitals provide acute and complex patient care. They are members of an organization called the Council of Academic Hospitals of Ontario (CAHO). Teaching hospitals are connected to a medical or health sciences school. They do research and they provide education and training for people who are, or are studying to be, health care professionals (e.g., medical interns and residents, nurses, physiotherapists).

Acute Care Hospitals treat patients for short but severe illnesses, for conditions that are due to disease or trauma (e.g., an accident) and during recovery from surgery.

Complex Care Hospitals treat patients who need 24-hour medical care and services that are not offered anywhere else. Their patients may have conditions (e.g., physical, cognitive or behavioural) that limit their ability to live independently in the community.

Very High-Volume Community Hospitals treat over 50,000 patients in their ER every year.

High-Volume Community Hospitals treat between 30,000 but less than 50,000 patients in their ER every year.

Medium-Volume Community Hospitals treat between 20,000 but less than 30,000 patients in their ER every year.

Low-Volume Community Hospitals treat less than 20,000 patients in their ER every year. In general, these hospitals are a community’s only available hospital.

Paediatric Hospitals treat only patients who are 18 years of age or less. In general, they provide all types of services for infants, children and young people.

Urgent Care Centres provide services without an appointment to patients who need treatment for non-life threatening conditions.

The CTAS Canadian Triage and Acuity Scale is a 5 point scale that ERs use to evaluate a patient’s acuity level to more accurately define the patient’s needs and allow for timely care.

CTAS I requires resuscitation. It includes conditions that are threats to life or imminent risk of deterioration, requiring immediate aggressive interventions (e.g., cardiac arrest, major trauma or shock states).

CTAS II requires emergent care. It includes conditions that are a potential threat to life or limb function requiring rapid medical intervention or delegated acts (e.g., head injury, chest pain, gastrointestinal bleeding, abdominal pain with visceral symptoms, or neonates with hyperbilirubinemia).

CTAS III requires urgent care. It includes conditions that could potentially progress to a serious problem requiring emergency intervention (e.g., mild moderate asthma or dyspnea, moderate trauma, or vomiting and diarrhea in patients younger than 2 years).

CTAS IV requires less urgent care. It includes conditions related to patient age, distress, or potential for deterioration or complications that would benefit from intervention or reassurance within 1 to 2 hours (e.g., such as urinary symptoms, mild abdominal pain, or earache).

CTAS V requires non-urgent care. It includes conditions in which investigations or interventions could be delayed or referred to other areas of the hospital or health care system (e.g., a sore throat, menses, conditions related to chronic problems, or psychiatric complaints with no suicidal ideation or attempts).

Why is there no data for some ERs?

In some cases, no information is available for a set period of time. The reasons are in the wait time data tables.


NA = Not Available

NC = Non-compliant. This means that a hospital was required to report wait times data for this service but did not report by the deadline for publication on this website.

NV = No, or low volume. This means that a hospital that is required to report, either reported that it did not have any ER visits during the period or the number of cases reported did not meet the indicator threshold.

NR = Not required to report. This means that a hospital was not required to report its data.

NS = No service information available.  This means that a hospital does not have Emergency Services.

RI = Reporting Issue. This facility did not meet the data quality criteria for reporting purposes. However the facility's data has been incorporated in the LHIN and Provincial level data.


The calculations include all cases of ER visits completed during the reporting time period.

The time spent in the ER is :

There are three calculations :  median time spent in ER, average time spent in ER and 90th percentile.

  1. Median time spent in ER - the length of time in which 5 out of 10 patients have completed their ER visit. Extreme values do not affect the median time spend in ER.
  2. Average time spent in ER - a typical length of a patient stay based on dividing the total time spent in ER of all ER visits, by the total number of visits. Extreme values do affect average time spent in ER.


Total time spent in the ER (hours) for all ER visits

Average Time Spent  =  


Total number of visits

  • 90th percentile -the maximum length of time in which 9 out of 10 patients have completed their ER visit. This is the default metric for public reporting of Total Time Spent in the ER.
  • Why are there differences between the average, median and 90th percentile data?

    A few cases that are excessively long can dramatically skew the data. This "skewing" effect is amplified if there is a small total number of cases. As a result, there may be a significant difference between the median, average and 90th percentile time spent in an ER for a specific visit.

    Using the median to measure time spent in ER eliminates this skewing. It gives a better indication of how long the "typical" patient will wait.

    Data Sources

    Hospitals submit the data electronically, using Level 1 NARCS (CIHI) to Cancer Care Ontario's Access To Care (CCO-ATC) Informatics Office.

    Data Quality

    The Ministry of Health and Long-Term Care ensures data accuracy and compliance with the reporting guidelines in several ways :

    The Ministry of Health and Long-Term has provided a Data Quality Framework to Cancer Care Ontario. Its Corporate Data Quality Improvement Team is the lead for these activities and it chairs the Access to Care Data Quality Working Group. For more information about data quality and the working group, please contact the team at

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