Escobedo v. Marshalls, CNA Ins. Co., 70 Cal. Comp. Cases 604 (WCAB 2005)
To be substantial evidence on apportionment, a medical opinion must be framed in terms of reasonable medical probability, not speculative, based on pertinent facts and adequate examination and history, and must set forth reasoning in support of its conclusions, including detailed explanation of degenerative changes and overlap with prior injuries.
The WCJ applied this standard to find Dr. Renbaum's apportionment opinion conclusory and not substantial evidence due to lack of detailed explanation and reasoning.
From the decision · page 6As stated in Escobedo, the mere fact that a report addresses the issue of causation of permanent
disability and makes an apportionment determination does not necessarily render the report one
upon which he WCAB may rely. This is because it is well established that any decision of the
WCAB must be supported by substantial evidence.2 Thus, to be substantial evidence on the issue
of apportionment, a medical opinion must be framed in terms of reasonable medical probability, it
must not be speculative, it must be based on pertinent facts and on an adequate examination and
history, and it must set forth reasoning in support of its conclusions. Moreover, in the context of
apportionment determinations, the medical opinion must disclose familiarity with the concepts of
apportionment, describe in detail the exact nature of the apportionable disability, and set forth the
basis for the opinion, so that the Board can determine whether the physician is properly
apportioning under correct legal principles. As the Board explained, if a physician opines that 50%
of an employee's disability is caused by degenerative changes, as Dr. Renbaum has done in this
instance, the physician must explain the nature of the degenerative changes, how and why they are
causing permanent disability, and how and why they are responsible for approximately 50% of the
disability.3
Kopping v. WCAB (2006) 71 CCC 1229
Employer must prove extent of overlap between prior disability and current disability for Labor Code section 4664 apportionment to apply.
The WCJ noted Dr. Renbaum did not discuss the extent of overlap between prior awarded disability and current disability, thus failing to meet the burden of proof for apportionment.
From the decision · page 7between the prior disability and the current disability.4 Here, Dr. Renbaum has not discussed the
extent of the overlap between the prior awarded disability with applicant's current disability, which
would have been rated under two different permanent disability schedules.
Finally, defendant asserts that, because Dr. Renbaum is an Agreed Medical Evaluator, the parties
are bound by his opinions. However, whether an evaluator is an AME or a QME, their opinions
must still be based on substantial medical evidence. In this instance, the undersigned found Dr.
Renbaum's opinion conclusory and not substantial evidence on apportionment. Defendant bears
the burden of proving apportionment. As discussed above, Dr. Renbaum's opinion, without
detailed discussion of the how and why as required by Escobedo5, is not substantial evidence of
apportionment. As such, the undersigned found applicant is entitled to an unapportioned award.