Filed 12/10/18
                          CERTIFIED FOR PUBLICATION


             IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA

                             FIRST APPELLATE DISTRICT

                                     DIVISION ONE


CITY OF PETALUMA et al.,
         Petitioners,
v.
THE WORKERS’ COMPENSATION                          A153811
APPEALS BOARD OF THE STATE OF
CALIFORNIA and AARON LINDH,                        (W.C.A.B. No. ADJ10032593)
        Respondents.
                                     INTRODUCTION
        In 2004, the Legislature made comprehensive changes to the workers’
compensation law, one of which altered apportionment of permanent disability such that
an employer is now liable only for the percentage of disability directly caused by the
employment-related injury. In the instant case, the Qualified Medical Examiner (QME)
concluded 85 percent of the claimant’s disability was due to a previously asymptomatic,
underlying condition. The Administrative Law Judge (ALJ), however, determined no
portion of the disability should be apportioned to that condition. The Workers’
Compensation Appeals Board (the Board) affirmed, stating the QME had “confused
causation of injury with causation of disability.” We granted the City’s petition for a writ
of review and now annul the decision and order an apportioned award.
                                      BACKGROUND
        The parties stipulated that the claimant, Aaron Lindh, was employed as a law
enforcement officer when he “sustained injury arising out of and in the course of
employment to his left eye.” More specifically, Lindh took three to six blows to the left
side of his head while engaged in a canine training course. Afterwards, he “suffered

                                             1
severe headaches lasting between several hours to one or two days.” Over a month later,
while off-duty, Lindh suddenly lost most of the vision in his left eye.
       Lindh saw two physicians, one at Kaiser and one at the University of California,
San Francisco (UCSF). The Kaiser physician evaluated Lindh as having “a left central
vein occlusion and retinal artery occlusion with afferent pupillary defect.” The UCSF
physician made “a diagnosis of combined central retinal vein occlusion/cilioretinal artery
occlusion in the left eye.” Neither physician believed the vision loss was related to the
blows to his head.
       Dr. David Kaye, a neuro-ophthalmologist and the QME who subsequently
evaluated Lindh, described Lindh as having “lost the central vision and part of his
peripheral vision.” He stated in his report and testified at deposition that there were “five
diagnoses” pertinent to Lindh—“Presbyopia. Hyperopia. Left ischemic optic
neuropathy. Left vitreous fibrosis and some retinal hemorrhages. History of migraine.”
Dr. Kaye explained that presbyopia and hyperopia are conditions requiring the individual
to wear reading glasses or “magnifying lenses.” “[L]eft ischemic optic neuropathy” is “a
condition in which the circulation to the nerve of the left eye was affected in effect
causing a stroke.” “[V]itreous fibrosis and some retinal hemorrhages,” Dr. Kaye
explained as, “when God makes the eye, he packs it full[] of jelly and the jelly sometimes
collapses and is replaced with scar tissue as in this case.”
       Dr. Kaye also concluded, as had the other physicians, that Lindh’s “blood
circulation to his left eye was defective.” He stated Lindh “did not have any disability
prior to receiving the blows to the head.” And “[a]bsent the injury,” he thought Lindh
“most likely would have retained a lot of his vision in that eye,” although he could not
“guess” how much. Dr. Kaye agreed “it [was] possible that [Lindh] could have gone his
entire life without losing vision.” He also agreed, however, that even had Lindh not
suffered the blows to his head, he still could have lost his vision “due to this underlying
condition.”
       As to apportionment, it was Dr. Kaye’s “opinion that [Lindh’s] underlying
vasospastic personality and vasculature placed him at high risk for damage to different


                                              2
parts of his body.” He further explained: “So when you ask the question for the cause of
injury, causation, I’m required to tell you that he does have an underlying condition,
vasospastic type, body type. I’m also required to tell you that the injury contributed to
his condition. . . . [¶] With regard to the cause of the disability, the same analysis
applies.”
       At a later point in his testimony, Dr. Kaye reiterated: “I’ve pointed out to both of
you that he has a vasospastic-type personality with a long history of migraine that’s
associated with this, and the majority of that is from his underlying condition and, yes, at
the time of a stress in his life such as at work or being smacked in the head with some
dogs, that places him at a much higher risk category and I’m comfortable in my own
mind attributing that to the severe loss of vision. [¶] . . . [¶] But not completely as I’ve
tried to make clear.” He subsequently repeated it was “unlikely” Lindh would have
suffered a vision loss if he had not had the “underlying condition” of “vascular
spasticity,” a condition that is “rare.”
       Again, in discussing his initial apportionment of 90 percent (which he adjusted to
85 percent), Dr. Kaye stated, “90 percent [is] due to the underlying condition and 10
percent due to the stress of the injuries,” the underlying condition meaning
“[v]asospastic-migraine body type.” He further agreed his opinion was to a reasonable
medical certainty.
       While Dr. Kaye had initially apportioned 90 percent of the cause of the disability
to Lindh’s underlying condition and 10 percent to “the results of the trauma,” after
reviewing “all the previous data again,” he stated both at deposition and in a follow-up to
his report that: “[I]t is my professional opinion that 85% of the patient’s permanent
disability is due to his old condition and 15% of the applicant’s permanent disability is
due to his industrial injury.” 1 (Underscoring omitted.)


       1
         In his report prior to his deposition, Dr. Kaye discussed apportionment as
follows: “Apportionment is indicated at this time. The mechanism is complex and this is
my understanding: [¶] [Lindh] has chronic migraine that I believe is on a vasospastic
basis. [¶] He has a hyper-reactive type personality. [¶] His work places him in an

                                               3
       The parties stipulated “the medical record, not including apportionment, rates 40
percent permanent disability, and with apportionment, rates six percent permanent
disability.”
       The ALJ rejected Dr. Kaye’s apportionment analysis, concluding it was not
supported by substantial evidence, and found Lindh had 40 percent permanent disability
without apportionment between his underlying condition and the work-related injury.
       After granting the City’s petition for reconsideration, the Board affirmed the
ALJ’s decision. As the Board saw it, “Dr. Kaye’s opinion establishes that applicant’s
preexisting hyperreactive type personality and his asymptomatic and . . . preexisting
systemic hypertension and vasospasm were mere risk factors that predisposed him to
having a left eye injury, but the actual injury and its resultant disability (i.e., the left eye
blindness) were entirely caused by industrial factors.” (Italics omitted.) “[A]n opinion
that bases apportionment upon the percentage to which non-industrial risk factors
contributed to causing the injury is not substantial evidence that legally justifies
apportionment.” (Italics omitted.) The Board concluded Dr. Kaye had “confused
causation of injury with causation of disability” and that “there is no legally valid basis
for apportionment in this case.”
                                          DISCUSSION
       “We review the Board’s factual findings for substantial evidence, but we review
its legal decisions de novo.” (City of Jackson v. Workers’ Comp. Appeals Bd. (2017)

environment that is associated with bouts of acute stress. [¶] This stress precipitated an
acute systemic hypertension and vasospasm that affected his left optic nerve vessels.
[¶] These vessels were predisposed to closure based on years of migraine. [¶] My
research of the literature supports this mechanism. [¶] As such, I apportion at least 90%
to this underlying migraine condition, recognizing that the exact mechanism is quite
difficult to ascertain. It should be noted that some young people develop a condition
called a branch or central vein vasculitis that presents like an adult version of central vein
occlusion. It is my opinion that the muzzled dog assault to the left side of his head
aggravated his underling condition. Bear in mind that it is possible that this patient had
lost some vision prior to this time and was injured by the dog on the left side because he
could not see. For this reason, I believe that 90% is due to underlying condition and 10%
due to the stress of his injuries.”


                                                4
11 Cal.App.5th 109, 114 (Jackson).) If “ ‘a workers’ compensation decision rests on the
Board’s erroneous interpretation of the law, the reviewing court will annul the
decision.’ ” (Acme Steel v. Workers’ Comp. Appeals Bd. (2013) 218 Cal.App.4th 1137,
1141 (Acme Steel).)
The 2004 Amendments Concerning Apportionment
       Prior to 2004, “[a]pportionment based on causation was prohibited.” (Brodie v.
Workers’ Comp. Appeals Bd. (2007) 40 Cal.4th 1313, 1326 (Brodie).) Thus, “to the
extent that a subsequent industrial injury exacerbated, accelerated, aggravated, or ‘lit up’
an applicant’s preexisting condition, the employer was liable for the resulting disability,
without apportionment.” (Escobedo v. Marshalls (2005) 70 Cal.Comp.Cases 604, 617,
fn. 9 (Escobedo).)
       Accordingly, prior to 2004, “employers were liable for the entire disability if the
disability arose in part from an interaction between an industrial cause and a
nonindustrial cause, but the nonindustrial cause alone would not have given rise to a
disability. [Citation.] Thus, an employer was liable for the entire disability if an
industrial injury aggravated a previously existing nonindustrial condition.” (Jackson,
supra, 11 Cal.App.5th at p. 115.) For example, in Zemke v. Workmen’s Comp. Appeals
Bd. (1968) 68 Cal.2d 794, 796 (Zemke), decided before the 2004 amendments, the
claimant suffered an injury to his back when he lifted a barrel at work. Three doctors
agreed the claimant had a preexisting “arthritic condition” that was asymptomatic before
the injury. (Id. at pp. 797–798.) The doctors variously described the preexisting
condition as osteoarthritic changes and degenerative disc disease. (Ibid.) The Board,
following the doctors’ opinion on apportionment, concluded 50 percent of the claimant’s
disability was attributable to the preexisting condition. (Id. at p. 799.) The Supreme
Court annulled the Board’s decision, holding “ ‘ “the employer takes the employee
subject to his condition when he enters the employment, and that therefore compensation
is not to be denied merely because the workman’s physical condition was such as to
cause him to suffer a disability from an injury which ordinarily, given a stronger and



                                              5
healthier constitution, would have caused little or no inconvenience.” ’ ” (Jackson, at
p. 115.)
       The 2004 enactment of Senate Bill No. 899 (2003–2004 Reg. Sess.) “overhauled
the statutes governing apportionment.” (Brodie, supra, 40 Cal.4th at p. 1323.) The
legislation also specified the act was “an urgency statute necessary for the immediate
preservation of the public peace, health, or safety within the meaning of Article IV of the
Constitution and shall go into immediate effect. . . . [¶] In order to provide relief to the
state from the effects of the current workers’ compensation crisis at the earliest possible
time, it is necessary for this act to take effect immediately.” (Stats. 2004, ch. 34, § 49;
Sen. Bill No. 899 (2003–2004 Reg. Sess.).)
       Thus, Labor Code section 4663 now provides in pertinent part: “(a)
Apportionment of permanent disability shall be based on causation. [¶] (b) A physician
who prepares a report addressing the issue of permanent disability due to a claimed
industrial injury shall address in that report the issue of causation of the permanent
disability. [¶] (c) In order for a physician’s report to be considered complete on the issue
of permanent disability, the report 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. If the physician is unable to include
an apportionment determination in his or her report, the physician shall state the specific
reasons why the physician could not make a determination of the effect of that prior
condition on the permanent disability arising from the injury. The physician shall then
consult with other physicians or refer the employee to another physician from whom the
employee is authorized to seek treatment or evaluation in accordance with this division in




                                              6
order to make the final determination.” (Lab. Code, § 4663, subds. (a)–(c), italics
added.) 2
       Labor Code section 4664, in turn, states: “The employer shall only be liable for
the percentage of the permanent disability directly caused by the injury arising out of and
occurring in the course of employment.” (Lab. Code, § 4664, subd. (a), italics added.)
Cases Applying the Amended Apportionment Statutes
       Given the significant changes to apportionment effectuated by the 2004
legislation, the courts and the Board have, in a number of cases, discussed the “other
factors” Labor Code section 4663, subdivision (c), now requires be taken into account in
apportionment, making clear that pathology and preexisting, asymptomatic conditions are
among such factors.
       In Escobedo, for example, the Board addressed the 2004 amendments in
connection with a claimant who fell and injured her knee at work and was subsequently
diagnosed as suffering from degenerative arthritis in her knees. (Escobedo, supra,
70 Cal.Comp.Cases at pp. 607–608.) 3 Prior to her injury, the claimant had never
consulted a physician about her knees, nor had she been subject to any work restrictions.
(Id. at p. 608.) The QME determined “ ‘it [was] medically probable that she would have
had fifty percent of her current level of knee disability at the time of today’s evaluation
even in the absence of her employment. . . .’ ” (Ibid.) Relying on the QME’s report, the
ALJ apportioned 50 percent of the permanent disability to nonindustrial causation given
her preexisting arthritis. (Id. at p. 609.)


       2
         Labor Code section 4663 does not apply to certain presumptively industrially-
caused injuries to certain peace officers under Labor Code sections 3212 through 3213.2.
(See Department of Corrections & Rehabilitation v. Workers’ Comp. Appeals Bd. (2008)
166 Cal.App.4th 911, 917.) There is no claim these statutory provisions are relevant
here.
       3
        Escobedo was decided en banc by “the Appeals Board as a whole” because of
“the important legal issues presented as to the meaning and application of [new Labor
Code] section 4663 with regard to the issue of apportionment of permanent disability
based on causation.” (Escobedo, supra, 70 Cal.Comp.Cases at p. 604.)


                                              7
       The Board discussed the changes brought about by the 2004 amendments at
considerable length: “Because the language of [Labor Code] section 4663 does not limit
the types of ‘other factors’ that may be considered as a non-industrial cause of permanent
disability, then the ‘other factors’ may include disability that was apportionable prior to
SB 899, i.e., the natural progression of a non-industrial condition or disease, a preexisting
disability, or a post-injury disabling event. (See former [Lab. Code,] §§ 4663, 4750,
4750.5.) In addition, the ‘other factors’ now may include pathology, asymptomatic prior
conditions, and retroactive prophylactic work preclusions, provided there is substantial
medical evidence establishing that these other factors have caused permanent disability.” 4
(Escobedo, supra, 70 Cal.Comp.Cases at p. 617, italics added.)
       The Board further observed that under amended Labor Code section 4663, the
“issue of the causation of permanent disability, for purposes of apportionment, is distinct
from the issue of the causation of the injury. [Citation.] Thus, the percentage to which
an applicant’s injury is causally related to his or her employment is not necessarily the
same as the percentage to which an applicant’s permanent disability is causally related to
his or her injury.” (Escobedo, supra, 70 Cal.Comp.Cases at p. 611, italics omitted.)
       The Board then addressed “whether an apportionment of permanent disability
[could] be made based on the preexisting arthritis in applicant’s knees.” (Escobedo,
supra, 70 Cal.Comp.Cases at p. 617.) It concluded that under the new law,
“apportionment now can be based on non-industrial pathology, if it can be demonstrated

       4
         The Board characterized the statutory changes as giving “renewed viability” to
older apportionment cases the Supreme Court had expressly rejected, such as Baker v.
Industrial Acc. Com. (1966) 243 Cal.App.2d 380 (Baker). (Escobedo, supra,
70 Cal.Comp.Cases at p. 618.) In Baker, the claimant, who had worked in various
industrial bakeries, eventually suffered from pulmonary emphysema so severe it
precluded employment. Several physicians were of the opinion the causes were multiple,
including allergic reactions to wheat flour and dust, lifelong smoking and chronic
alcoholism. (Baker, at pp. 383–384, 387–388.) The Industrial Accident Commission
found the claimant suffered from a disability which “derive[d] from both industrial and
nonindustrial causes,” and the Court of Appeal affirmed an apportioned award. (Id. at
pp. 390–391 [“all of the factors leading to the petitioner’s disability were not produced by
an industrial injury”].)


                                              8
by substantial medical evidence that the non-industrial pathology has caused permanent
disability.” (Id. at p. 618.) The Board went on to conclude substantial medical evidence
supported apportionment of the claimant’s permanent disability to her arthritis, citing the
QME’s characterization of the “ ‘trivial nature’ ” of her at-work injury and his opinion
the claimant would have had 50 percent of her current level of knee disability even in the
absence of her employment. (Id. at p. 622.)
       In Brodie, our Supreme Court considered a group of five cases in which claimants
with prior injuries or preexisting conditions sought permanent disability under the
amended law. (Brodie, supra, 40 Cal.4th at pp. 1317–1319.) The court granted review
specifically to determine how permanent disability compensation should be computed
when a claimant has “a level of permanent disability and . . . some but not all of that
current level of permanent disability is properly apportioned to the most recent industrial
injury.” (Id. at p. 1320.) In the course of deciding that question, the court summarized
the changed law on apportionment.
       Prior to 2004, “former [Labor Code] section 4663 and case law interpreting the
workers’ compensation scheme closely circumscribed the bases for apportionment.
Apportionment based on causation was prohibited.” (Brodie, supra, 40 Cal.4th at
p. 1326.) Accordingly, “a disability resulting from industrial and nonindustrial causes
was apportionable ‘only if the [B]oard finds that part of the disability would have resulted
from the normal progress of the underlying nonindustrial disease.’ [Citation.] This rule
left employers liable for any portion of a disability that would not have occurred but for
the current industrial cause; if the 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.” (Ibid.)
       In enacting the 2004 amendments, the Legislature “intended to reverse” a number
of the features of the worker’s compensation law, including “eliminat[ing] the bar against
apportionment based on pathology and asymptomatic causes. . . .” (Brodie, supra,
40 Cal.4th at p. 1327.) “[T]he new approach to apportionment is to look at the current
disability and parcel out its causative sources—nonindustrial, prior industrial, current


                                              9
industrial—and decide the amount directly caused by the current industrial source.” 5 (Id.
at p. 1328.)
       In E.L. Yeager Construction v. Workers’ Comp. Appeals Bd. (2006)
145 Cal.App.4th 922 (E.L. Yeager), the Court of Appeal considered a claim by a
construction worker who fell and injured his lower back. The QME apportioned 20
percent of the injury to preexisting asymptomatic degenerative disc disease. (Id. at
p. 925.) The ALJ, however, found no basis for apportionment, and the Board denied
reconsideration. (Id. at pp. 924–925.) In annulling the award, the appellate court first
explained:
       “In 2004, the Legislature made a diametrical change in the law with respect to
       apportionment to an employee’s preexisting injury by enacting Senate Bill No.
       899 (2003–2004 Reg. Sess.) (Senate Bill 899). Prior to its repeal by this bill,
       apportionment under Labor Code former section 4663, was limited to
       circumstances where the apportioned disability was the result of the natural
       progression of a preexisting, nonindustrial condition and such nonindustrial
       disability would have occurred in the absence of the industrial injury.
       Apportionment based on causation was prohibited. Thus, ‘[p]rior to 2004,
       apportionment could never be made on the basis of pathology, either in a case of
       preexisting disability or in a case of an aggravation of an existing condition; it had
       to be made on the basis of causation of permanent disability. Many times the
       reporting physician might find preexisting pathology, such as old x-rays showing
       asymptomatic spinal changes or heart disease that could not have happened
       overnight, but these were insufficient, absent actual disability, for apportionment.’
       (1 Hanna, Cal. Law of Employee Injuries and Workers’ Compensation (rev. 2d ed.
       2006) Apportionment—Specific Applications, § 8.06, p. 8–36.1, fns. omitted.) [¶]

       “ ‘The rule under the law prior to [Senate Bill] 899 was “an employer takes the
       employee as he finds him at the time of the employment. Accordingly, when a
       subsequent injury lights up or aggravates a previously existing condition resulting
       in disability, liability for the full disability without proration is imposed upon the
       employer, and the appeals board may apportion the disability under [former
       section 4663] ‘only in those cases in which part of the disability would have
       resulted, in the absence of the industrial injury, from the “normal progress” ’ of the
       preexisting disease. [Citations.]” [Citation.] That is, the [Board] was required to

       5
        With respect to the specific computational issue before it, the high court
concluded “formula A,” as set forth in Fuentes v. Workers’ Comp. Appeals Bd. (1976)
16 Cal.3d. 1, was the appropriate one. (Brodie, supra, 40 Cal.4th at p. 1324.)


                                             10
       “allow compensation not only for the disability resulting solely from the
       employment, but also for that which results from the acceleration, aggravation, or
       ‘lighting up’ of a prior nondisabling disease.” [Citation.] Apportionment was
       allowed in limited situations, but could not be based on the cause of the disease;
       “pathology” could not be apportioned. [Citations.]’ (Rio Linda Union School
       Dist. v. Workers’ Comp. Appeals Bd. (2005) 131 Cal.App.4th 517, 525–526 . . .
       (Rio Linda).) [¶]

       “ ‘[Senate Bill] 899 repealed former [Labor Code] section 4663. [Senate Bill] 899
       added a new section 4663 and section 4664 affirmatively requiring, among other
       things, apportionment of permanent disability based on causation and limiting the
       employer’s liability under certain circumstances. [Citations.]’ (Rio Linda, supra,
       131 Cal.App.4th at p. 526. . . .)” (E.L. Yeager, supra, 145 Cal.App.4th at pp. 926–
       927, fns. omitted.)

       Accordingly, in its answer in E.L. Yeager, the Board acknowledged that
“apportionment may be based on pathology and asymptomatic prior conditions.” (E.L.
Yeager, supra, 145 Cal.App.4th at p. 927.)
       The court then turned to the Board’s assertion that, nevertheless, the QME’s
opinion did not constitute substantial evidence necessitating apportionment. (E.L.
Yeager, supra, 145 Cal.App.4th at p. 927.) The court agreed “the mere fact” a
physician’s report apportions causation is not conclusive, pointing out “to constitute
substantial evidence, a medical opinion must be predicated on reasonable medical
probability.” (Id. at pp. 927–928.) Further, “a medical opinion is not substantial
evidence if it is based on facts no longer germane, on inadequate medical histories or
examinations, on incorrect legal theories, or on surmise, speculation, conjecture, or
guess.” (Id. at p. 928.) However, the court concluded the QME’s apportionment opinion
suffered from no such inadequacies. (Id. at pp. 929–930.)
       While the Board complained the QME acknowledged the prior condition had not
previously caused any period of disability, the appellate court reiterated that “prior
disability or evidence of modified work performance is no longer a prerequisite to
apportionment.” (E.L. Yeager, supra, 145 Cal.App.4th at p. 929.) “[D]egenerative
disease can be asymptomatic and still apportionable under the new law.” (Ibid.)



                                             11
       The court ultimately concluded, that while “paying lip service” to the new
statutory scheme, the Board had rejected the QME’s apportionment opinion based on a
view of apportionment that was no longer the law. (E.L. Yeager, supra, 145 Cal.App.4th
at p. 930.) In short, the court concluded none of the reasons offered by the Board for
rejecting the QME’s apportionment opinion was supportable, annulled the Board’s
decision and remanded for an apportioned award. (Id. at pp. 929–931.)
       In Acme Steel, supra, 218 Cal.App.4th 1137, this court similarly annulled an
award that failed to apportion the claimant’s disability to nonindustrial factors. In that
case, the claimant suffered “continuous trauma injury to his ears” while employed at
Acme and eventually had a “100 percent” hearing loss. (Id. at p. 1139.) The QME
concluded 60 percent of the hearing loss was due to “ ‘occupational factors, specifically
noise[-]induced hearing loss,’ ” and 40 percent was the result of “non-occupational
factors, particularly cochlear degeneration.” (Ibid.) The ALJ, however, rejected the
QME’s opinion on apportionment because there had been “ ‘no earnings loss’ ” in
connection with a prior disability award for hearing loss following an explosion, and the
claimant had “ ‘continued to work.’ ” (Id. at p. 1141.) The Board denied
reconsideration. (Ibid.)
       We annulled the decision, explaining “the [Board] ignored substantial medical
evidence . . . showing that [the applicant’s] 100 percent loss of hearing could not be
attributed solely to the current cumulative trauma. [Citation.] Faced with this unrebutted
substantial medical evidence . . . the [Board] should have parceled out the ‘causative
sources—nonindustrial, prior industrial, current industrial—and decide[d] the amount
directly caused by the current industrial course.’ ” (Acme Steel, supra, 218 Cal.App.4th
at p. 1143, quoting Brodie, supra, 40 Cal.4th at p. 1328.) As the court had done in E.L.
Yeager, we remanded for an apportioned award. (Acme Steel, at p. 1144.)
       In Jackson, the claimant, a police officer, suffered a work-related injury to his
neck that required surgery. (Jackson, supra, 11 Cal.App.5th at pp. 112–113.) The QME
concluded the claimant’s disability had multiple causes, including “personal history,”
which included cervical degenerative disc disease caused in large part by heredity or


                                             12
genetics. (Id. at pp. 113–114.) The physician apportioned 49 percent of the disability to
the claimant’s “personal history, ‘including “genetic issues,’ ” and the ALJ issued an
apportioned award. (Id. at pp. 113–114.) The Board reversed and ordered a non-
apportioned award. (Id. at p. 114.) The Court of Appeal annulled the Board’s decision
and remanded with directions to deny reconsideration, thus affirming the ALJ’s
apportioned award. (Id. at p. 112.)
       The court rejected the Board’s assertion that apportioning causation on the basis of
“ ‘ “genetics” opens the door to apportionment of disability to impermissible immutable
factors.’ ” (Jackson, supra, 11 Cal.App.5th at p. 115.) As the court pointed out,
“[p]recluding apportionment based on ‘impermissible immutable factors’ would preclude
apportionment based on the very factors that the legislation now permits, i.e.,
apportionment based on pathology and asymptomatic prior conditions for which the
worker has an inherited predisposition.” (Id. at p. 116.)
       The court also rejected the Board’s assertion that “ ‘[r]relying upon applicant’s
genetic makeup’ ” had caused the QME “ ‘to apportion the causation of applicant’s injury
rather than apportionment of the extent of his disability.’ ” (Jackson, supra,
11 Cal.App.5th at pp. 117–118.) While the court recognized that in Escobedo, the Board
had commented “ ‘the percentage to which an applicant’s injury is causally related to his
or her employment is not necessarily the same as the percentage to which an applicant’s
permanent disability is causally related to his or her injury,’ ” (id. at p. 118, quoting
Escobedo, supra, 70 Cal.Comp.Cases at p. 611), it pointed out the Board had also
recognized that “does not mean the two cannot be the same.” (Jackson, at p. 118, fn. 4,
citing Kos v. Workers’ Comp. Appeals Bd. (2008) 73 Cal.Comp.Cases 529, 533.) The
court further explained that the QME had not engaged in a misdirected apportionment
analysis—he had properly determined that the claimant had suffered a cumulative injury
from repetitive motion, and had then apportioned the claimant’s disability, that is, his
debilitating neck, arm, hand and shoulder pain that prevented him from performing his
duties. (Jackson, at p. 118.) Accordingly, “[c]ontrary to the Board’s opinion,” the QME
“did not apportion causation to injury rather than disability.” (Ibid.)


                                              13
       The court went on to conclude that the QME’s opinion constituted “substantial
medical evidence” supporting apportionment. (Jackson, supra, 11 Cal.App.5th at
p. 119.) “Substantial evidence is relevant evidence a reasonable mind might accept as
adequate to support a conclusion. (Braewood Convalescent Hospital v. Workers’ Comp.
Appeals Bd. (1983) 34 Cal.3d 159, 164. . . .) In Escobedo, supra, 70 Cal.Comp.Cases at
page 620, the Board opined that in order for a medical opinion to constitute substantial
evidence, it must be predicated on reasonable medical probability. It must also set forth
the reasoning behind the physician’s opinion. (Id. at p. 621.) In the context of an
apportionment determination, the 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.’ (Ibid.) A medical opinion must be
framed in terms of reasonable medical probability, must not be speculative, must be
based on pertinent facts and on adequate examination and history, and must set forth the
reasoning in support of its conclusions. (Ibid.)” (Jackson, at p. 119.)
       The QME had examined the claimant and reviewed his medical records. (Jackson,
supra, 11 Cal.App.5th at p. 113.) She had also reevaluated him after surgery. Her
diagnosis remained unchanged, but she changed her apportionment analysis on the basis
of several medical publications, which she named and discussed. (Id. at pp. 113, 120.) In
short, the QME’s medical reports met “all the requirements of Escobedo” and she
“expressly stated that confidence in her opinion was predicated on a reasonable degree of
medical probability.” (Id. at p. 121.) She gave “the reasoning behind her opinion” and
“disclosed familiarity with the concept of apportionment.” (Ibid.) “She explained that
the causation of [the claimant’s] disability stemmed from work activities with the City,
prior work activities, prior personal injuries, and personal history. Included in the causes
listed as personal history were ‘heritability and genetics’ as supported by medical studies,
[the claimant’s] brief history of smoking, and his prior diagnosis of lateral epicondylitis.”
(Ibid.) Her reports “reflect, without speculation, that [the claimant’s] disability is the
result of cervical radiculopathy and degenerative disc disease. Her diagnosis was based


                                              14
on medical history, physical examination, and diagnostic studies that included X-rays and
MRI’s (magnetic resonance imaging scans). She determined that 49 percent of his
condition was caused by heredity, genomics, and other personal history factors. Her
conclusion was based on medical studies that were cited in her report, in addition to an
adequate medical history and examination.” (Ibid.) Accordingly, the QME’s reports
were “more than sufficient to meet the standard of substantial medical evidence.” (Ibid.)
Apportionment Is Required
       Echoing the contentions made and rejected in these cases, Lindh similarly claims
Dr. Kaye’s opinion does not constitute substantial medical evidence of apportionment.
He asserts Dr. Kaye “did exactly what is prohibited by Brodie [] and Escobedo [], in that
he based the apportionment on risk factors,” alone, which cannot support apportionment.
He further claims, again citing to Escobedo, that Dr. Kaye “confused the issues of
causation of injury with the issue of causation of disability.” 6
       Lindh points to the following interchange at the outset of Dr. Kaye’s deposition as
support for his assertions:
       “Q: [¶] Would you agree that Mr. Lindh’s migraine headaches in this case are
       nothing more than a risk factor for losing his eyesight?
       “A: Yes. [¶] . . . [¶] So when you ask the question for the cause of injury,
       causation, I’m required to tell you that he does have an underlying condition,
       vasospastic type, body type. [¶] I’m also required to tell you that the injury
       contributed to his condition. If you want me to put that in legal terms, rely on your
       experience, I would just suppose this. [¶] With regard to the cause of the
       disability, the same analysis applies.
       “Q: And what is that analysis?
       “A: Absent the injury of March of that year, it’s my position that he most likely
       would have retained a lot of his vision in that eye.
       “Q: Are you able to determine how much of his vision he would have retained?
       “A: No. I can’t guess.

       6
         Amicus California Applicants’ Attorney’s Association (CAAA), appearing in
support of Lindh, advances the same claims. It maintains that the City has erroneously
advocated “that the percentage of causation of an injury should be the same as the
percentage apportionment” and “that apportionment to risk factors that may never cause
any disability is legally permitted.” This, says CAAA, “conflates causation of injury with
causation of permanent disability.”


                                              15
       “Q: Is there any way to determine when he would have begun losing vision
       without the blows to the head?
       “A: No.
       “Q: Is it possible that he could have gone his entire life without losing vision?
       “A: Yes.”

       But contrary to Lindh’s assertions, this excerpt reflects that Dr. Kaye, in fact,
understood the distinction between the causes of an injury and the causes of a disability.
What he said was that in this case they were the same, which the Board has recognized
can be the case. (Jackson, supra, 11 Cal.App.5th at p. 118, fn. 4; see Escobedo, supra,
70 Cal.Comp.Cases at p. 613 [“percentage to which an applicant’s injury is causally
related to his or her employment is not necessarily the same as the percentage to which
an applicant’s permanent disability is causally related to his or her injury,” italics
added].)
       Furthermore, as we have recited at length above, this truncated excerpt does not
fairly reflect Dr. Kaye’s medical opinion. His subsequent explanation of his diagnoses
and opinion as to apportionment makes clear that he attributed Lindh’s disability (i.e.,
impaired vision) to both the work-place injury and an “underlying condition.” 7 (Italics
added.) And when asked about this “underlying condition,” Dr. Kaye repeatedly
identified it as “vasospastic-type personality.” That he also referred to this underlying
condition as putting Lindh at “higher risk” of suffering the disability, does not change the
fact that Lindh had an underlying condition (and one, according to Dr. Kaye, that is

       7
          While there is no disagreement as to what constituted Lindh’s “disability” (i.e.,
his seriously impaired vision), there is some disagreement as to what constituted his
industrial “injury.” In the administrative proceedings, the parties stipulated that “on June
16, 2015, applicant sustained industrial left eye injury.” That was not the day on which
Lindh received the blows to his head, but the day many weeks later, when he was not at
work, that he suddenly lost vision. Accordingly, as the parties have used the terms, there
is scarcely a distinction between the industrial “injury” and the immediately ensuing
“disability.” Amici California Workers’ Compensation Institute (CWCI) and California
Association of Joint Powers Authorities (CAJPA), appearing in support of the City, take
a different view—that the workplace “injury” was the trauma to Lindh’s head and the
“disability” is his impaired vision. However, we need not, and do not, parse the precise
meaning of the term “injury” here to resolve this case.


                                              16
relatively rare) that was, along with the work-place injury, a cause of his impaired vision.
Thus, the Board’s comment in Costa is apt: “Applicant’s argument that the WCJ
improperly apportioned to a risk factor ignores the medical opinion that applicant’s pre-
existing congenital condition went beyond being a risk factor to being an actual cause of
his increased permanent disability, when applicant sustained his industrial injury.”
(Costa v. Workers’ Comp. Appeals Bd. (2011) 76 Cal.Comp.Cases 261, 264; see State
Comp. Ins. Fund v. Workers’ Comp. Appeals Bd. (2007) 146 Cal.App.4th 1311, 1315
[“ ‘ “[W]hen the Board relies upon the opinion of a particular physician in making its
determination, it may not isolate a fragmentary portion of his report . . . and disregard
other portions that contradict or nullify the portion relied on; it must give fair
consideration to all of his findings. . . .” ’ ”].)
       Lindh also seemingly conflates his asymptomatic condition—vasospasticity
personality and vasculature—with his history of migraine headaches, which history he
also characterizes as simply a “risk factor.” But even if characterized as a “risk factor,”
his history of migraines reflected an underlying condition that in Dr. Kaye’s opinion was
largely the cause of his loss of vision. Dr. Kaye’s opinion was also entirely consistent
with the opinion of the treating physicians at UCSF and Kaiser, both of whom were of
the opinion it was unlikely the head trauma Lindh sustained at work caused his
subsequent loss of vision.
       While Lindh purports to acknowledge the post-amendment cases requiring
apportionment to nonindustrial causes that, along with an industrial cause, result in a
disability, he maintains these cases are “inapplicable” because they “involve[d]
degenerative disease . . . [which] implies that there would be some progressive disease
process.” Because his preexisting asymptomatic condition might “never have resulted in
disability or vision loss,” Lindh claims his disability cannot be apportioned.
       To begin with, Dr. Kaye not only posited that, absent the blows to his head, Lindh
might “have gone his entire life without losing vision,” he also agreed Lindh could have
lost his vision, even without the work place trauma, “due to this underlying condition.”
In short, in Dr. Kaye’s view, either outcome might have occurred.


                                                 17
       More importantly, the post-amendment cases do not require medical evidence that
an asymptomatic preexisting condition, in and of itself, would eventually have become
symptomatic. Rather, what is required is substantial medical evidence that the
asymptomatic condition or pathology was a contributing cause of the disability. (See
Brodie, supra, 40 Cal.4th at p. 1328 [“the new approach to apportionment is to look at the
current disability and parcel out its causative sources—nonindustrial, prior industrial,
current industrial—and decide the amount directly caused by the current industrial
source”].)
       In fact, Lindh’s suggestion that apportionment is required only where there is
medical evidence the asymptomatic preexisting condition would invariably have become
symptomatic, even without the workplace injury, reflects the state of the law prior to the
2004 amendments. As Jackson explained, prior to the 2004, “employers were liable for
the entire disability if the disability arose in part from an interaction between an industrial
cause and a nonindustrial cause, but the nonindustrial cause alone would not have given
rise to a disability. [Citation.] Thus, an employer was liable for the entire disability if an
industrial injury aggravated a previously existing nonindustrial condition.” (Jackson,
supra, 11 Cal.App.5th at p. 115, italics added; see Brodie, supra, 40 Cal.4th at p. 1326;
Escobedo, supra, 70 Cal.Comp.Cases at p. 614 [under prior law, “there must have been
medical evidence establishing that some definable portion of the applicant’s permanent
disability would have occurred as the result of the natural progression of a non-industrial
condition or disease, even absent the industrial injury”].)
       Under the current law, the salient question is whether the disability resulted from
both nonindustrial and industrial causes, and if so, apportionment is required. (See
Brodie, supra, 40 Cal.4th at p. 1328; Jackson, supra, 11 Cal.App.5th at pp. 116–117;
Acme Steel, supra, 218 Cal.App.4th at p. 1142.) Whether or not an asymptomatic
preexisting condition that contributed to the disability would, alone, have inevitably
become manifest and resulted in disability, is immaterial.
       Thus, while a number of cases have involved asymptomatic preexisting conditions
involving a “degenerative” disease, including Jackson (cervical degenerative condition


                                              18
caused in large part by heredity and genetics), Acme Steel (congenital degeneration of the
cochlea), and E.L. Yeager (degenerative disease of the lumbar spine), no case has
suggested that that particular medical terminology is indicative of a legal requirement for
apportionment. (See Jackson, supra, 11 Cal.App.5th at p. 117 [“We perceive no relevant
distinction between allowing apportionment based on a preexisting congenital or
pathological condition and allowing apportionment based on a preexisting degenerative
condition caused by heredity or genetics.”].)
       To the contrary, the post-amendment cases uniformly focus on whether there is
substantial medical evidence the disability was caused, in part, by nonindustrial factors,
which can include “pathology and asymptomatic prior conditions for which the worker
has an inherited predisposition.” 8 (Jackson, supra, 11 Cal.App.5th at p. 116; see

       8
           At oral argument, the CAAA and Board similarly maintained, in support of
Lindh, that an asymptomatic preexisting condition must be “degenerative” in the sense
that, even without the industrial injury, the condition would eventually lead to some
degree of disability. Accordingly, while the CAAA and Board acknowledged
apportionment would be required where, for example, an industrial injury and
asymptomatic “degenerative” disc disease both contributed to impaired mobility due to a
ruptured disc, they insisted the instant case is different. On questioning, it became
apparent the difference lay in their assumption that “degenerative” disc disease would,
even without an industrial injury, eventually become symptomatic and cause some degree
of impaired mobility. However, we fail to see any material distinction between that
ruptured disc example and the instant case. There is no support for their apparent
assumption that asymptomatic “degenerative” disc disease will inevitably result in a
ruptured disc and restricted mobility. Furthermore, their seeming insistence that there
must be medical evidence that an asymptomatic preexisting condition will, in and of
itself, naturally progress to disable the claimant, reflects the law prior to 2004. None of
the cases they cite suggest this continues to be the law. (E.g., Target Corp. v. W.C.A.B.
(2016) 81 Cal.Comp.Cases 1192, 1193–1194 [physicians failed to provide substantial
medical evidence, e.g., failed to explain the how and why, to support apportionment
percentages]; Hikida v. Worker’s Comp. Appeals Bd.(2017) 12 Cal.App.5th 1249, 1252
[“despite significant changes in the law governing workers’ compensation in 2004,
disability resulting from” surgical procedure for an industrial injury (carpel tunnel
syndrome) “for which the employer is responsible is not subject to apportionment”];
ATC/Vancom, Inc. v. W.C.A.B. (2014) 79 Cal.Comp.Cases 1329, 1330–1331 [employer
did not met its burden of proving claimant’s psychiatric disability should be apportioned
to nonindustrial factors].)


                                            19
Escobedo, supra, 70 Cal.Comp.Cases at p. 617 [separately listing, and thus distinguishing
between, all the “factors” that are apportionable—including those apportionable prior to
2004 (“the natural progression of a non-industrial condition or disease, a preexisting
disability, or a post-injury disabling event”) and those apportionable after 2004
amendments (“pathology, asymptomatic prior conditions, and retroactive prophylactic
work preclusions”)].)
       There is also no merit to Lindh’s claim that there can be no apportionment to a
condition that caused no disability prior to the work-related injury. By definition, an
asymptomatic preexisting condition has not manifested itself and, thus, by definition has
not caused a prior disability. (See E.L. Yeager, supra, 145 Cal.App.4th at p. 929 [“[P]rior
disability or evidence of modified work performance is no longer a prerequisite to
apportionment. If the presence of these factors is necessary to constitute substantial
evidence, there would have been no purpose in changing the law.”].)
                                           DISPOSITION
       The Workers’ Compensation Appeals Board’s opinion and decision after
reconsideration is annulled, and the matter is remanded to the Board with directions to
make an award apportioning Lindh’s disability 85 percent to his preexisting condition
and 15 percent to his industrial injury.




                                               20
                                             _________________________
                                             Banke, J.


We concur:


_________________________
Humes, P.J.


_________________________
Margulies, J.




A153811; City of Petaluma et al. v. Workers’ Compensation Appeals Board




                                        21
Trial Judge: Hon. Jason E. Schaumberg

Counsel:

Mullen & Filippi, LLP, William E. Davis for Petitioner City of Petaluma.

Ellen Sims Langille for California Workers’ Compensation Institute as Amicus Curiae on
behalf of Petitioner.

John Frederick Shields Jr. for Respondents Workers’ Compensation Appeals Board.

Law Offices of Linda J. Brown, Karina Kowler for Respondent Aaron Lindh.

Gearheart & Sonnicksen, Mark Gearheart for California Applicants’ Attorney
Association as Amicus Curiae on behalf of Respondent Aaron Lindh.




                                          22
