Challenging Causation Opinions in California Work Injury Claims
In California work injury claims disputes relating to compensability of an injury are determined based on an injured worker’s testimony and opinion of physicians. However, in the majority of cumulative trauma cases, a worker’s testimony as to the repetitive nature of work, vibration, and forces will invariably lead to a finding of cumulative trauma injury. The scientific basis for the physician’s findings is rarely questioned nor do physicians bother to provide a scientific rationale for their determination regarding causation. Yet, in the majority of the cases, popularly held beliefs that repetitive work and heavy physical labor invariably cause injuries such as neck/back pain, carpal tunnel syndrome or meniscal tears are unsupported by scientific medical evidence.
Need for Substantial Medical Opinion
In California, to constitute substantial evidence, a medical opinion must be predicated on reasonable medical probability (McAllister v Workermen’s Comp App Bd (1968) 69 Cal 2d. 408).
Page 11, Section 1.6a of the 5th Edition of the AMA Guides to the Evaluation of Permanent Impairment provides the following regarding causation:
“Physicians may be asked to provide an opinion about the likelihood that a particular factor (injury, illness or preexisting condition) caused the permanent impairment. Determining causation is important from a legal perspective, as it is a factor in determining liability……Medical or scientifically based causation requires a detailed analysis of whether the factor could have caused the condition, based upon scientific evidence and, specifically, experienced judgement as to whether the alleged factor in the existing environment did cause the permanent impairment. Determining causation requires a synthesis of medical judgement with scientific analysis.”
Resource for Causation Standards
In California, the standard for causation in work injuries is evidence-based medicine from scientific research. The publication of the 2nd Edition, AMA Guides to the Evaluation of Disease and Injury Causation provides a scientific basis for challenging the physician’s findings regarding causation and apportionment.
Challenging Causation Opinions
Reports finding cumulative trauma neck injury from work are routinely accepted as normal and routinely go unchallenged by defendants. However, there is insufficient scientific evidence for neck posture, heavy physical work, prolonged work in a sedentary position or repetitive and precision work as risk factors for neck pain. Similarly, there is insufficient scientific evidence for heavy work by itself as a risk factor for low back pain.
Any kind of work that involves repetitive use of the upper extremities invariably leads to a finding of industrial causation for carpal tunnel syndrome. However, recent studies have shown computer keyboard use does not increase the risk of CTS, and the prevalence of this condition in computer users being similar to the general population.
The defense attorney should fully understand the risk factors for a particular injury and obtain detailed job description before confronting the physician. The risk factors for the majority of work injuries can be found in the Guides.
Challenging Apportionment Opinions
Where a frontal assault on causation for a particular injury is unsuccessful, provision of scientific evidence setting out the injured worker’s risk factors for the particular injury can result in substantial apportionment.
In the recent Court of Appeal, 3rd Appellate District decision in City of Jackson v. WCAB (Christopher Rice), a panel QME’s decision holding that genetic issues were causative factors that merit apportionment was upheld.
Defendant should ensure that they identify all potential non-industrial risk factors associated with the injury in question and frame appropriate questions to the injured worker at the time of deposition to confirm the risk factors.
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