SB863 swept the Workers’ Compensation legislation with vast and significant changes. One area remained unreformed, apportionment, which had undergone significant changes in the 2004 by SB899.

In Brodie v. WCAB, 40 Cal.4th 1313, the California Supreme Court discussed the former Labor Code section 4663 and case law interpreting the bases for apportionment. Apportionment based on causation was prohibited (Pullman Kellogg v. WCAB, 26 Cal.3d 450). A disability resulting from industrial and nonindustrial causes was apportionable only if the Board found that part of the disability would have resulted from the normal progress of the underlying nonindustrial disease.

Employers would be on the hook for any portion of a disability that would not have occurred, but for the current industrial cause. If a disability arose in part from an interaction between an industrial cause and a nonindustrial cause, but the nonindustrial cause would not alone have given rise to a disability, no apportionment was to be allowed (Ballard v. WCAB (1971) 3 Cal.3d 832).

The amended Labor Code section 4663 provides:

1. Apportionment of permanent disability shall be based on causation;
2. Any physician who prepares a report addressing the issue of permanent disability due to a claimed industrial injury shall in that report address the issue of causation of the permanent disability;
3. In order for a physician’s report to be considered complete on the issue of permanent disability, it must include an apportionment determination. A physician shall make an apportionment determination by finding what approximate percentage of the permanent disability was caused by the direct result of injury arising out of and occurring in the course of employment and what approximate percentage of the permanent disability was caused by other factors both before and subsequent to the industrial injury, including prior industrial injuries.

In Thomas v. Long Beach Unified School, CWC Lexis 317, a noteworthy panel decision, Ms. Thomas suffered several admitted industrial injuries to the upper extremities and spine. An orthopedic Agreed Medical Evaluator (AME) found 50% apportionment to industrial factors and 50% apportionment to non-industrial factors. The WCJ followed the findings of the AME and awarded a 50% reduction in permanent disability.

The WCAB relied on two en banc decisions in reversing the WCJ’s finding on apportionment: Escobedo v. Marshalls, 70 CCC 604 and E.L. Yeager Construction v. WCAB (Gatten), 146 Cal.App.4th 922. These cases have provided guidance by utilizing a checklist to ensure a physicians report will be found to be substantial evidence.

1. Dr. must make a specific apportionment determination, using percentages, based on the PD that existed at the time of the evaluation of the applicant;
2. Dr. must analyze PD based on causation of disability;
3. Dr.’s opinion must not be speculative, it must be based on pertinent facts and on an adequate examination and history;
4. Dr.’s opinions must be based on reasonable medical probability;
5. Dr. must explain how and why they arrived at their conclusion.

In Thomas, the WCAB reviewed the reporting of the AME as compared to the guidelines provided in Gatten and Escobedo. It was held the AME’s findings were not justified and merely conclusionary. The AME’s opinion on apportionment was found not to constitute substantial medical evidence because it lacked the ‘how and why’ in addition to failing to state an opinion in terms of reasonable medical probability.

When the issue of apportionment arises, which it frequently does, assess the AME/PQME’s findings with the above-mentioned checklist to make sure all elements have been addressed. Use these points in deposing or requesting for a supplemental report to ensure the reporting is found to be substantial evidence.