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Helping employers, insurance carriers, third-party administrators and self-insured groups navigate workers’ compensation defense.

Zurich North American v. WCAB

Case Summary:

On Jan. 16, 2001, applicant, a salesperson for Holt, Rinehart & Winston, sustained injuries to her neck, lower back and both upper extremities in an automobile accident during the course of employment. After returning to work in Oct. 2001, applicant sustained multiple CT injuries to her neck and back from Oct. 2001 to Mar. 18, 2002 and from Sep. 5, 2002 to Jun. 20, 2003, a specific injury to her knees and back on Oct. 3, 2002, and another CT injury to her knees, wrists, upper extremities, neck, and back from Oct. 2001 to Jun. 30, 2003. Liberty Mutual Insurance Company provided workers’ compensation coverage from Oct. 1, 2001 through Dec. 31, 2001, and Zurich North America provided coverage thereafter from Jan. 1, 2002 through Jun. 30, 2003.

According to Lab. Code §4663, apportionment based on causation requires a finding of a percentage of the permanent disability “caused by the direct result of injury arising out of and occurring in the course of employment” and an approximate percentage of the permanent disability “caused by other factors both before and subsequent to the industrial injury, including prior industrial injuries.” Furthermore, if a physician is unable to make an apportionment determination, the physician must specify the reasons and consult with, or refer the employee to other physicians for a final determination.

In the present case, there were conflicting medical reports on whether applicant’s injuries can be apportioned. Initially, an AME (agreed upon by applicant and Liberty Mutual) concluded that the applicant was 100% permanently totally disabled and that the contribution of her successive injuries to the overall disability could not be separated, whereas a QME (obtained by Zurich) concluded that applicant’s permanent disability might be apportioned. After settling her claims involving Liberty Mutual in 2010, applicant sought to receive compensation from Zurich for the injuries sustained during Zurich’s coverage. As a result, further medical reports were obtained in 2011, including the report of applicant’s treating physician. The treating physician, similar to the AME, concluded that it was impossible to determine which injury dates caused which portions of applicant’s overall disability and that her injuries could not be apportioned.

In agreeing with the decision of the WCJ, the WCAB concluded that the treating physician’s report should take precedence over the QME’s report due to its thoroughness in explaining how the evolution and combination of the applicant’s successive injuries had resulted in permanent total disability, the causation of which could not be parceled. As a result, the Board held that Zurich was liable for 100% of PD without apportionment.


This case applies the exception raised in Benson v. W.C.A.B. 170 Cal. App. 4th 1535 (2009) where the court stated that a combined permanent disability award may be justified in limited circumstances. These limited circumstances are “when the evaluating physician cannot parcel out, with reasonable medical probability, the approximate percentages to which each distinct industrial injury causally contributed to the employee’s overall permanent disability.”

As in most cases in which apportionment is an issue and particularly in successive injury cases involving the same body parts, whether a physician will be able to parcel out the causes of permanent disability the results are particularly fact sensitive. This case illustrates that the requirement to parcel out causation under Benson is not automatic just because there are multiple or successive injuries. It is defendant’s burden to conduct careful discovery through depositions, medical reports and other sources to establish the subject and objective effects of each injury to develop facts upon which a physician may apportion liability. Although the AME report was not binding on Zurich, as Zurich apparently was not a party to the agreement to use an AME, and generally a QME opinion would be given more weight than the opinion of a treating physician regarding medical legal issues, the AME opinion was no doubt influential on the opinion of the treating physician and board as the treating physician did review the AME report.

In the present case, the WCJ stated that the QME underestimated the full nature and extent of the applicant’s injury in determining apportionment, whereas the treating physician offered a more detailed rationale why apportionment would be impossible. Ultimately, the most persuasive medical report is the one that provides sound reasoning and is based on a solid factual record, particularly when the medical report is in conflict with other reports.