EHSLaw Update

Unlike all other Canadian jurisdictions, Ontario's workers compensation regime was without a specific policy on pre-existing conditions, until recently. On November 1, 2014, a new Workplace Safety & Insurance Board (WSIB) policy on Pre-Existing Conditions came into force. The underlying premise of the policy is to provide decision makers with guidance on how to draw the work-related/non-work-related line when it comes to adjudicating claims involving pre-existing conditions.

Challenges of Adjudicating Claims with Pre-Existing Conditions

Workers compensation regimes in Canada are based on the premise that workers are entitled to benefits when they sustain a work related injury. In many cases, the link between an injury and a work related event is clear. When pre-existing conditions are present, however, the adjudication process can become a lot more challenging and complex. Pre-existing conditions are typically viewed as conditions that do not have their origins in the workplace but instead are the result of non-work related factors such as degeneration or prior injuries. When workplace and non-workplace factors are present, questions arise as to how to adjudicate them in ways that are fair to the worker but, at the same time, ensure that the worker's compensation system is not compensating for situations that are the result of non-workplace conditions.

Ontario's New Policy: Core Elements

The new policy purports to provide guidance in decision making and consistency to outcomes for both workers and employers. Its core elements include:

  1. Definition of Pre-Existing Condition: A pre-existing condition is defined as a condition that existed prior to a work related injury/disease. It includes injuries, diseases, degenerative conditions and psychiatric conditions, as confirmed by clinical evidence.
  2. Entitlement: An explicit statement that entitlement will not be denied due to the existence of a pre-existing condition. Further, ongoing entitlement may only be affected where it is shown that the pre-existing condition is impacting the worker's ongoing impairment. This would mean that compensation for an injury would not be discounted due to any pre-existing condition the worker may have.
  3. "Crumbling Skull" and "Thin Skull" Legal Principles: The policy encompasses the "crumbling skull" and "thin skull" doctrines, which are well established legal principles and components of decision making at the WSIB. The "Crumbling Skull" Doctrine seeks to limit entitlement to benefits to the injury that is work-related. This means that workers are entitled to benefits only for the acute episode, such that benefits stop as soon as he or she returns to his or her pre-accident state. The "Thin Skull Doctrine," holds that the compensation system must take the worker as it finds him/her: pre-existing, pre-dispositions do not affect entitlement.
  4. Work-Relatedness and the "Significant Contributing Factor" Test: The "significant contributing factor" test is well established in WSIB practice and court jurisprudence. The new Policy includes the "significant contributing factor" test and states that when assessing the impact of the pre-existing condition on the worker's ongoing impairment, the decision maker must determine whether the work related injury continues to be a significant contributing factor.

Considerations for Employers

The question of how to fairly assess cases involving pre-existing conditions on the part of an injured worker remains a complex and problematic issue for decision makers. Although Ontario's new policy aims to provide clarity and consistency to claim-related outcomes, employers should always keep a close eye on claims involving pre-existing conditions and take steps to ensure that decision makers are following the requirements set out in law and Policy with respect to pre-existing conditions, in particular the following: 

  • Objective medical evidence is crucial in any case involving pre-existing conditions.
  • Although employers are responsible for injuries that are at least a significant contributing factor, they are not responsible for compensating workers for injuries that are unduly remote (e.g. a non-work related contributing factor so dominant as to constitute an "intervening cause" which breaks the chain of causation).
  • The presence of a pre-existing condition does not necessarily mean it has any impact on a worker's impairment. Ontario's new policy, for example, sets out a number of factors for the decision maker to consider when determining initial and ongoing entitlement, including whether the impairment affects the same body part as the pre-existing condition and whether the impairment continues beyond the expected recovery period, given the work related injury.

Financial relief may be available in cases involving pre-existing conditions through the WSIB's Secondary Injury Enhancement Fund or aggravation basis policy. Finally, employers should always exercise their right to appeal any and all questionable claims and decisions.

The Pre-Existing Conditions policy is available on the WSIB website, Operational Policy Manual 15-02-03.