Document name
Pre-Existing Conditions – Aggravation or Acceleration
Document number
PRO 12/2017

Effective date: October 1, 2017

Application: Applies to all injuries on and after the effective date where there is a pre-existing condition.

Policy subject: Decision making - Principles


To establish adjudication guidelines for claims where pre-existing conditions exist.


Policy section content
Section detail

POL 12/2017, Pre-Existing Conditions – Aggravation or Acceleration establishes guidelines for injury claims where pre-existing conditions exist.


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  1. Once Operations staff determine the worker has a pre-existing condition that may affect their recovery from the work-related injury, they must determine:
    1. The extent of the work-related injury.
    2. The extent of the aggravation or acceleration of the pre-existing condition by the work-related injury.
    3. If the worker has recovered from the work-related injury.
  2. Operations staff will gather information about the pre-existing condition from:
    1. The worker.
    2. Health care providers by obtaining medical confirmation of the pre-existing condition.
    3. Past and present employers and coworkers, and other insurers, if necessary.
  3. Operations staff will review:
    1. Any history of prior problems in the same or nearby areas of the body as the work-related injury.
    2. The effect(s) of any pre-existing condition on the worker leading up to the work injury (i.e., pre-injury status).
    3. Relevant medical reports regarding the worker’s pre-existing condition.
  4. Operations staff may request a WCB Medical Consultant’s opinion to help clarify the extent of a work-related injury in relation to a pre-existing condition.
  5. Operations staff will notify workers when compensation benefits will be terminated once they have recovered from the injury and are able to return to pre-injury employment or suitable productive employment (POL 11/2021, Terminating Benefits – Notice Period).

Policy references

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Section heading

Legislative Authority

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The Workers’ Compensation Act, 2013
Sections 2(1)(r), 20, 26, 31, 49, 103.

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Document History

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(1)    November 1, 2021. Clarification added for when the termination of compensation benefits may occur for workers in accordance with POL 11/2021, Terminating Benefits – Notice Period.
(2)    POL and PRO 01/2000, Pre-Existing Condition – Section 49 (effective May 1, 2000 to September 30, 2017).
(3)    POL 17/94, Pre-Existing Conditions (effective August 16, 1994 to April 30, 2000).

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