A police officer sustains several blows to the head during canine training. He experiences severe headaches. Some weeks later, while off duty, he suddenly loses most of the vision in one eye. Medical evaluation reveals a problem with blood circulation to the eye. It also reveals an underlying condition associated with a long history of migraines. The officer had not previously experienced disabling vision problems. A California Qualified Medical Evaluator (QME) must now apportion the resulting permanent disability. How much did the industrial injury cause, and how much did the underlying condition cause?
This was the situation in City of Petaluma v. Workers’ Compensation Appeals Board (Lindh), decided by the California Court of Appeal in 2018. The question it addressed is one every California QME faces sooner or later. Can a pre-existing condition that caused no prior disability still contribute to permanent disability after an industrial injury?
The answer, it seems, is yes, but only under the right circumstances. A condition that increases the risk of injury does not automatically qualify as a cause of permanent disability. As with most of their opinions, the QME must justify and explain how the condition actually contributed to the disability. The Lindh decision offers important lessons about how to make that distinction and why it matters in a medical-legal evaluation.
The California QME’s Role in Assigning Apportionment
When an injured worker reaches Maximum Medical Improvement (MMI), the assigned QME must address permanent impairment. Where applicable, the QME must also give an opinion on how much of the permanent disability the claimed industrial injury caused. Under California Labor Code section 4663, causation is the basis for apportionment of permanent disability.
The evaluator states the approximate percentage of permanent disability caused by the industrial injury. The remainder then goes to other factors, including pre-existing conditions.
This raises two similar but distinct questions:
- What caused the injury or medical condition?
- What caused the permanent disability?
There may be some overlap in the answers, but it is a mistake to assume they are the same question. A condition may increase a worker’s susceptibility to injury without necessarily contributing to the resulting permanent disability. Conversely, a pre-existing condition may contribute to permanent disability even if it had not previously caused symptoms or functional limitations. OrthoLegal’s earlier article on causation of injury versus causation of permanent disability looks at that distinction in more detail.
The Lindh Decision: An Asymptomatic Condition Can Contribute to Permanent Disability
Aaron Lindh, a police officer, sustained blows to the left side of his head during a canine training course. He subsequently experienced severe headaches lasting several hours or longer. Some weeks later, while off duty, he suddenly lost most of the vision in his left eye.
Treating physicians diagnosed a serious problem involving blood circulation in the eye. They did not connect the vision loss to the blows to his head.
The QME, however, identified an underlying condition he described as a “vasospastic-migraine body type.” It involved a history of migraines and an underlying vascular abnormality that affected circulation. Although Lindh had experienced occasional mild headaches, he had not previously suffered disabling vision loss.
The QME first apportioned 90% of Lindh’s permanent disability to the underlying condition and 10% to the industrial injury. After a second review of the medical information, he revised the split to 85% pre-existing and 15% industrial.
The parties challenged the opinion, and the workers’ compensation judge rejected the apportionment. The Workers’ Compensation Appeals Board (WCAB) subsequently affirmed that decision. In its reasoning, the pre-existing conditions were risk factors that made Lindh more susceptible to injury. Yet nobody had established them as causes of his resulting permanent disability.
The matter was not yet concluded. On review, the Court of Appeal disagreed with the WCAB and annulled its decision. It remanded the case with directions to make an award apportioning 85% of Lindh’s disability to the pre-existing condition and 15% to the industrial injury.
The court emphasized that an asymptomatic pre-existing condition can contribute to permanent disability. It does not matter that the condition had not previously produced symptoms or functional limitations. Nor was it necessary to establish that the condition would inevitably have caused disability on its own in the future. The important thing was whether substantial medical evidence supported the conclusion. Did the condition actually contribute to the permanent disability that occurred?
What Lindh Means for a QME Evaluation
The Lindh decision does not mean that every asymptomatic condition or medical risk factor justifies apportionment. Rather, it clarifies that the absence of prior symptoms or disability does not automatically rule out apportionment. Simply stating that a condition carries an increased risk of injury is not enough. The evaluator still has to show that the condition contributed to the disability in front of them.
When evaluating a pre-existing condition, QMEs should ask one question. Does the medical evidence establish a causal contribution to the current permanent disability? The report should then explain the underlying pathology, how it contributed to the disability, and the medical reasoning supporting any assigned percentage.
Applying the Principle: Carpal Tunnel Syndrome and Diabetes
A data-entry clerk develops carpal tunnel syndrome after years of typing and repetitive hand and wrist activity at work. During the evaluation, the QME learns that the worker also has a history of diabetes. Diabetes carries an increased risk of carpal tunnel syndrome. Its presence alone does not establish that any portion of the worker’s permanent disability belongs to that condition.
Should the QME apportion a percentage of disability to diabetes? As usual, the answer depends on the medical evidence.
For example, does the worker have evidence of diabetic neuropathy or other diabetes-related pathology? Is there evidence that the condition contributed to the current sensory deficits, functional limitations, or other permanent impairment? Can the evaluator explain how that contribution differs from the effects of the industrial injury?
The QME’s challenge is to decide whether the medical evidence establishes a causal connection between the pre-existing condition and the current permanent disability. If the evidence does not support that connection, the condition’s status as a recognized risk factor is not enough to justify apportionment.
The Importance of Staying Current
Apportionment is one of the most consequential parts of a QME’s evaluation. An unsupported opinion can affect the permanent disability determination and lead to disputes, depositions, and additional evaluations. It can also damage a QME’s reputation and ability to obtain work. Staying current with medical research, reporting requirements, and relevant legal developments helps QMEs recognize the issues that require closer analysis.
The Lindh decision is a useful reminder that sound medical-legal reporting requires more than identifying diagnoses and assigning percentages. It relies on understanding the applicable legal framework and clearly explaining the medical basis for each conclusion.
Frequently asked questions
Does Lindh mean every risk factor supports apportionment?
No. Lindh holds that the absence of prior symptoms does not rule out apportionment. It does not hold that a risk factor is a cause. The evaluator still has to show, with substantial medical evidence, that the condition contributed to the disability itself. Contributing to the likelihood of the injury is not the same thing.
What should the apportionment section of a California QME report contain?
The underlying pathology. An explanation of how it contributed to the current permanent disability. The medical reasoning behind the approximate percentages assigned to the industrial injury and to other factors. If the evaluator cannot make a determination, Labor Code section 4663 requires the report to give the specific reasons.
Can a QME apportion to a condition that never caused symptoms?
Yes, when the medical evidence supports it. In Lindh, the Court of Appeal held that an asymptomatic pre-existing condition can contribute to permanent disability. It also need not have been inevitably disabling on its own. What matters is the causal contribution the evaluator can explain in the report.
Continuing Education for California QMEs
Continuing education is key to helping QMEs work through these questions and communicate their reasoning clearly. To that end, OrthoLegal offers educational programs, including its DWC-approved 16-hour Report Writing Course and workshops focused on the practical demands of medical-legal reporting. These programs help evaluators strengthen their understanding of reporting requirements and develop clearer, better-supported medical opinions.
For QMEs, staying educated is not simply a professional obligation. It is an important part of producing reports that accurately address causation and support defensible apportionment opinions. Those reports give the parties the insight to understand the full picture of the claim. OrthoLegal supports qualified medical evaluator work across California with scheduling, records and report support. Learn more on our page for physicians, or call 213.947.0000.
This article is general information for medical-legal evaluators about California workers’ compensation, not legal advice. For a specific case, refer to the current regulations or consult counsel.