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This is an archive of the Task Force on Adverse Health Events website, which was last updated in December 2008, and will not be updated further. If you have difficulty accessing any material, please contact Executive Council.


The term adverse event is often used interchangeably with other terms such as sentinel event, adverse outcome and critical incident. The following are definitions that have been used by Canadian organizations.

An unexpected event in healthcare delivery that results in harm to the patient and is related to the care and/or services provided to the patient, rather than to the patient’s underlying medical condition. (Canadian Patient Safety Institute. Canadian Disclosure Guidelines, March 2008).

An unexpected incident, related to system or process deficiencies, which leads to death or major and enduring loss of function for a recipient of health care services. Major and enduring loss of function refers to sensory, motor, physiological, or psychological impairment not present at the time services were sought or began. The impairment lasts for a minimum period of two weeks and is not related to an underlying condition. (Canadian Council on Health Services Accreditation - Sentinel Events).

Adverse outcome should be understood to mean not only a non-trivial adverse outcome or consequence of health care treatment which manifests itself in the course of or following health care treatment, but also an incident in the course of health care treatment which results in a recognized potential risk of a non-trivial adverse outcome or consequence at some future time. (College of Physicians and Surgeons of Newfoundland and Labrador, Disclosure of Adverse Outcome, 2006).

Note: The Task Force on Adverse Health Events has not yet adopted a standard set of definitions for the many terms related to adverse events management and patient safety. A useful glossary can be found on the CPSI website.

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