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Letters to the Editors

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• Warren Schneider
• Marjory Harris





In the first article in a series of editorials
on “Workers’ Compensation Disabled:
What Went Wrong on the Road to Reform?”
we explore the legal and scientific
underpinnings to the current concept of
apportionment of permanent disability.
We look at common logical fallacies we
have found in reports, deposition transcripts
and case law, and how to overcome these
with research and specific questions. We
propose a method for evaluating
apportionment – IPECAC – similar to the
IRAC method we used in law school –
and provide a downloadable guide you
can print out and take to any apportionment

Like the last set of reforms in 1989, SB 899,
signed into law on April 19, 2004, was
meant to reduce litigation and get the
lawyers out of the system. One of its most
unlikely assumptions was that a physician
could divine what percentage of permanent
disability was the direct result of the
industrially-caused condition or its side
effects, as opposed to "other factors." This
has led to endless litigation in the
"apportionment wars."

In this article we discuss the science and the fiction behind Labor Code §4663.

Labor Code §4663, in relevant part
(a) Apportionment of permanent
disability shall be based on causation.
(b) 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.
(c) 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. For the entire statute, click here.

At the unveiling of the new Section 4663,
there was considerable speculation about
what "other factors" meant, and whether
one could apportion to asymptomatic
pathology. In the more than two years
since SB 899, there has been only one
significant legal opinion on this issue, the
Escobedo case. It opens the door to many
more questions than answers. It requires
opinions by both physicians and workers'
compensation judges. On pages 2 and 3
of the opinion, the Commissioners set forth
5 holdings. For full text, click here.

Escobedo v. Marshalls (2005) 70 Cal. Comp. Cases 604 (Appeals Board en banc opinion), pet. for rev. den. sub nom. Escobedo v. W.C.A.B. (2005) 70 Cal. Comp. Cases 1506 (writ denied).

1) “Causation” in L.C. 4663(a) refers to the causation of the permanent disability, not causation of the injury.
2) Both a reporting physician and the WCAB must make determinations of what percentage of the permanent disability was directly caused by the industrial injury and what percentage was caused by other factors.
3) The applicant has the burden of establishing the percentage of permanent disability directly caused by the industrial injury, and the defendant has the burden of establishing the percentage of disability caused by other factors.
4) Apportionment caused by “other factors both before and subsequent to the industrial injury, including prior industrial injuries,” may include not only disability that could have been apportioned prior to SB 899, but it also may include disability that formerly could not have been apportioned (e.g., pathology, asymptomatic prior conditions, and retroactive prophylactic work preclusions), provided there is substantial medical evidence establishing that these other factors have caused permanent disability.
5) Even where a medical report “addresses” the issue of causation of the permanent disability and makes an “apportionment determination” by finding the approximate relative percentages of industrial and non-industrial causation under section 4663(a), the report may not be relied upon unless it also constitutes substantial evidence.

The Escobedo board recited some rules
for the substantial evidence requirement:
"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."

"Substantial evidence" "if true, has probative force on the issues. It is more than a mere scintilla, and means such relevant evidence as a reasonable mind might accept as adequate to support a conclusion. It must be reasonable in nature, credible, and of solid value.'" Braewood Convalescent Hospital v. WCAB (1983) 34 Cal.3d 159, 164


Legal Fiction: Doctors can assign percentages of causation

Science Fiction: It sounds true at
first light,
but like a mirage, is a lie by
noon, to paraphrase Hemingway. As I read
the apportionment paragraphs of forensic
reports, I usually find no substance to
support the percentages.

In the common law tradition, legal
fictions are suppositions of fact
taken to be true by the courts of law,
but which are not necessarily true.

Are physicians scientists? Their
observations are usually documented only
in individual charts, not as studies across
their practice. Thus, they are anecdotal
observations, not meeting the scientific
requirements of reliability, validity and rigor.

It is the legal advocate's duty to insist on
rigor (the quality of being logically valid) in
forensic reports. This requires close
analysis of the facts of the case, medical
research, and clearly worded explanations.
If the physician does not do this, the
burden shifts to the lawyer to formulate
the correct analysis and to pose carefully
worded questions.

Use the IPECAC method as an outline or checklist (see below)

The Scientific Method: Seeking
Reliability, Validity and Rigor

The scientific method is a body of techniques for investigating phenomena and acquiring new knowledge, as well as for correcting and integrating previous knowledge. It is based on observable, empirical, measurable evidence, and subject to laws of reasoning. All such evidence is collectively called scientific evidence. Wikipedia http://en.wikipedia.org/wiki/

Evidence-based medicine (EBM) applies the scientific method to medical practice. According to the Centre for Evidence-Based Medicine, "Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients."

Apportioning to Epidemiological Studies – the Camel's Nose Intrudes into the Tent…

There are various good arguments
against allowing apportionment to
epidemiological traits. There is, of course,
the "eggshell skull" doctrine that one takes
the victim as one finds him or her. There
are the anti-discrimination statutes of the
State and Federal governments. And then
there is science. While the various types of
epidemiologic studies are a valuable tool
for science, in identifying what to study
further, where to invest limited resources,
and the like, such studies rarely apply to
everyone. We need to focus on the
individual whose benefits are being
diminished and ask how probable is it that
genetics or other epidemiologic factors
played a role in causing the permanent
disability not in the population being
studied, but in this particular worker?

And in fairness, we need to assume that
this worker could be one of those who do
not have the problem being studied, unless
there is other proof beyond mere statistics.

"Epidemiology is the scientific study of factors affecting the health and illness of individuals and populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. It is considered a cornerstone methodology of public health research, and is highly regarded in evidence-based medicine for identifying risk factors for disease and determining optimal treatment approaches to clinical practice.

Strictly speaking, epidemiology can only go to prove that an agent could have caused but not that, in any particular case, it did cause: "Epidemiology is concerned with the incidence of disease in populations and does not address the question of the cause of an individual’s disease. This question, sometimes referred to as specific causation, is beyond the domain of the science of epidemiology. Epidemiology has its limits at the point where an inference is made that the relationship between an agent and a disease is causal (general causation) and where the magnitude of excess risk attributed to the agent has been determined; that is, epidemiology addresses whether an agent can cause a disease, not whether an agent did cause a specific plaintiff’s disease."

Remember IRAC?

I have created the "IPECAC" method for analyzing apportionment issues:


I – Issue (Is there any percentage of permanent disability attributable to factors
other than the industrial injury?) If yes, go
to the next step.

P – Premise (what is the physician's
premise for apportionment to non-industrial
factors?)(e.g., obesity causes knee
problems – epidemiologic risk factor)

E – Erudition, or knowledge acquired
through study and reading, and Evidence.
This is a requirement of the new paradigm
of "evidence-based medicine" (EBM).
Anything less is anecdotal and likely the
"ipse dixit" logical fallacy.

C – Causal relationship and the weighing
of counter evidence: Even if there is EBM to
support the premise, is there evidence that
does not support the premise? In other
words, does the EBM show cause and
effect or simply correlation? If not
dispositive of the issue, proceed to the
next step (do studies show that all obese
people have knee problems? Or that if
bones are malaligned, obesity then
causes problems?)

A – Application or Analysis: how does
this relate to the facts of this case and this
injured worker? Connect all the dots!
("This IW has obesity and malaligned

C – Conclusion re: causation. Is the
conclusion logically derived from the
premise, the erudition and evidence, the
weighing of causes and counter evidence,
and the facts of the instant case? If not,
examine further for logical fallacies,
contrary studies, and legal attacks based
on case law, other laws such as FEHA, concepts of fairness, Labor Code §3202,
etc. and the like.

IPECAC for analyzing apportionment:

Erudition & Evidence
Causal Relationship & Counter Argument
Application & Analysis
Conclusion re: Causation

Click here to download a chart to take with you to depositions. It summarizes IPECAC and includes questions to support or refute apportionment

"If She Sinks, She's Not A Witch":
Spotting Logical Fallacies Used to
Support Apportionment

It was just a few hundred years ago that
trial by water, or the swimming of witches,
was used to determine if the defendant
was a witch. "It was believed that water
rejected servants of the devil and that if a
suspected person floated and refused to
sink when placed in water it was proof of
guilt." That it might be proof that the person
knew how to float or doggy paddle or even
swim, or that the person was being kept
afloat by those who held onto the ropes,
seems not to have been considered.
While the logical fallacy that supported the
"indicium aquae" seems patent today, the
logical fallacies supporting much of the
apportionment paragraphs in our medical-
legal reports may be harder to spot.

"A fallacy is a general type of appeal
(or category of argument) that
resembles good reasoning, but that
we should not find to be persuasive."



The usual report has something like this:
"The patient's MRI indicates degenerative
changes in the lumbar spine. I estimate
approximately 50 percent of her current
disability can be apportioned to preexisting
degenerative disc disease and
spondylosis and approximately 50 percent
can be attributed to her work activities of
frequent heavy lifting." No explanation is
given, no studies cited. In fact, the studies
that are available do not support this
opinion. This is the "ipse dixit" fallacy, that
it is true because the doctor says so.

Ipse dixit violates Escobedo: "The opinion
of the expert is no better than the reasoning
upon which it is based." If there is no
reasoning, there is no substantial evidence.

If the doctor insists that his or her own
experience is sufficient, remind him/her
of this: "The practice of evidence based
medicine means integrating individual
clinical expertise with the best available
external clinical evidence from systematic
research.” (Sackett DL, Straus S,
Richardson S, Rosenberg W, Haynes RB.
Evidence-based Medicine: how to practice
and teach EBM, ed 2. London: Churchill
Livingston, 2000.) Ask what "external
clinical evidence from systematic research"
supports his or her view.

"Ipse Dixit" Latin for "he himself said it." The term labels something that is asserted but unproved.

This authority-based approach is not consistent with the new medical model of "EBM," evidence-based medicine, which looks to randomized controlled trials, as well as systematic reviews (of a series of trials), meta-analysis, etc.

Here is one that apportions to post-injury
inability to exercise, leading to weight
gain, in someone who worked on her
feet all day before the work injury: "As far
as apportionment is concerned, I
recommend that disability be apportioned
25% to her underlying degenerative disk
disease, 25% to her exogenous obesity
(which is a significant factor in her failure
to improve), and 50% to the incident on
February 25, 2004." No explanation is
given, another "ipse dixit" and adding a
"false cause"

Non Causa Pro Causa: Latin for "Non-cause for cause." Alias: False Cause

"Mistakes about type-level causation are the result of confusing correlation with causation. Two types of event may occur simultaneously, or one type always following the other type, without there being a causal relation between them. One common source of non-causal correlations between two event-types is when both are effects of a third type of event."

"Cum Hoc, Ergo Propter Hoc" is the fallacy committed when one jumps to a conclusion about causation based on a correlation between two events, or types of event, which occur simultaneously. In order to avoid this fallacy, one needs to rule out other possible explanations for the correlation. http://www.fallacyfiles.org/

Converting causation of injury into
causation of permanent disability – not
allowed by Escobedo:
While alcohol
consumption may have played a role in
causing avascular necrosis, if the afflicted
bone is removed and the residuals are
due to a joint replacement, then the cause
of the injury has nothing to do with the
cause of the permanent disability. "Here,
we conclude that there is no basis for
apportionment of applicant's permanent
knee disability. Dr. Isono reported that
applicant's need for right knee
replacement surgery was caused by
various factors, including industrial and
non-industrial factors. However, medical
treatment is not apportionable. (Granado v.
Workmen's Compo Appeals Rd. (1968)
69 Ca1.2d 399 [33 Ca1.Comp.Cases 647].
Moreover, despite the various causes for
the knee replacement surgery, applicant's
work limitation to semi-sedentary work,
according to Dr. Isono, is due to the knee
replacement and the symptoms related to
the prosthesis. Thus, while we held in
Escobedo v. Marshalls, supra, that
apportionment of permanent disability
under section 4663(a) may be based on
any "other factor", here there are no "other
factors" that caused permanent knee
disability. Rather, the permanent knee
disability was caused by the knee
replacement and the symptoms
associated with the prosthetic knee
replacement. Therefore, under section
4663 and Escobedo V. Marshalls, supra,
we conclude that there can be no
apportionment of applicant's permanent
knee disability in these matters."
Board panel decision, Steinkamp v. City
of Concord
, issued March 30, 2006,
writ denied

Speculation: "I think if you have a
spondylolisthesis you are set up for future
back problems, but there are people that
have it that don't have back problems. So,
it is my best estimate of what is reasonable
and I don't have much more scientific
evidence to back it up other than that's my
very best estimate." [Franey v. State Farm
Ins. Co., SAL 108549, June 23, 34 CWCR
186 (2006)

2006, Order Denying Reconsideration

Speculation or Speculative Evidence: The argument draws a conclusion from an assertion about what the evidence would show if one were actually to look at it; however, the argument appeals to evidence that has not actually been collected or does not actually exist.

Reliance on Unavailable Evidence:

"Q. Do you have any specific study that you can point to? A. I don't have them memorized. Q. Would you be able to produce that for us? A. I could spend hours hunting them down."

Confusing orthopedic permanent
disability with psychiatric permanent
The defense QME opines,
"I know this is very complicated. I would
like to be sure that this is all as clear as
possible. To summarize: Dr. [AQME] and I
basically agree that about 30% of Ms. IW's
permanent psychiatric disability is non-
industrial, period. This 30% is attributable
to factors that have nothing to do with her
work at [hospital], regardless of any
orthopedic disputes. The issue is that the
remaining 70% of psychiatric disability
changes, depending on which orthopedic
opinion is accepted. The more orthopedic
disability that is ultimately found to be of
non-industrial cause, the more Ms. IW's
psychiatric disability (resulting from chronic
pain and so on) is likewise non-industrial.
To the extent that permanent orthopedic disability is attributed to one industrial
injury or the other, there is correspondingly
more permanent psychiatric disability
attributable to that injury."

Huh? If 70% of the psychiatric permanent
disability is caused by the effects of the
industrial injury, why would it be further
changed by looking at the percentage of
causation of the permanent disability
related to the industrially-caused orthopedic
injuries? This could turn into an endlessly
shifting algorithm. Is this the red herring
fallacy? Sure seems smelly.

"Red Herring" - A logical fallacy in which the premise is logically unrelated to the conclusion

Does not meet Escobedo: "Absent that
underlying pathology, he would be better
off today or to put it another way, his
underlying pathology has contributed to
his disability." Panel majority found this
insufficient to support apportionment as it
failed the "how and why" test of Escobedo,
since there was no explanation given for
why applicant would be better off had it not
been for the underlying pathology.
Wood v. SCIF: 34 CWCR 15 (2005)

Does meet Escobedo: "With regard to
apportionment, Dr. Levin concluded that
50 percent of Applicant's disability was
related to her pre-existing underlying
degenerative arthritis. In a subsequent
report, Dr. Levin opined that Applicant's
disability could be attributed to the
chondroplastic surgery performed by
Dr. Kingsley, which consisted of shaving
the articular surface of Applicant's lateral
femoral condyle and tibial plateau and
would be necessary for osteoarthritis but
not for a simple tear of the meniscus. He
concluded that the level 9 or 10 disability
described by Applicant in her deposition
was much more consistent with her
pre-existing osteoarthritis than with a tear
of the meniscus and its resection."
Beery v. WCAB, 70 Cal. Comp. Cas 1334 (2005)

"As I consider apportionment in the post-4/04 and post-Escobedo world, the question of apportionment to pathology and/or degenerative conditions plainly takes on a very heightened importance. To qualify as a likely basis for apportionment, in my opinion, the pathology being cited has to be outside the norm for the patient's age in comparison to the general population. Also, it would be significant if the pathology had previously "announced" itself in some fashion over time via records or by the patient's history of diminished activity or some awareness of symptoms. I recognize, as well, the ability to now apportion to asymptomatic prior conditions, in which case, the situation would not have "announced itself." I generally expect that would apply when the pathology was quite marked, such that its extent would argue against the patient's protestation of wellness pre-injury. Another example would be when the pathology is so striking that a physician could readily concede and conclude that it was likely the wellspring of much of the disability." From an Agreed Medical Evaluator's report

How to Smoke Out Bogus Apportionment: Some Key Questions

Although apportionment is an affirmative
defense and the burden is on the
defendant to prove apportionment (see
Escobedo and Labor Code §5705), it may
be risky to leave it unchallenged, unless
no explanation whatsoever is given for the
apportionment percentage. Otherwise,
one needs to probe for legal and medical

First, examine the language used by
Dr. Ovadia in Escobedo: "Although denying
any prior problems with her knees, it is
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 at
Marshalls." This passed the Escobedo
tests because 1) there is medical
probability and 2) the pathology would
have caused ratable disability at the time
of the evaluation even in the absence of
a work injury.

The law makes a legal distinction between "possibility" and "probability." Opinions based upon possibility are not necessarily admissible. Therefore, if the doctor uses any of the following phrases in connection with his or her opinion, such testimony may be stricken by the judge: (1) It "might be" true. (2) It "is possible." (3) It "might have" that effect. (4) It "could have" that effect.

Click here for some examples where the examiner eliminated the apportionment after the questions were posed. Note that the facts of the particular cases were developed as a prelude to the questions.

To refute apportionment to preexisting,
asymptomatic pathology,
inquire along these lines:

How and why does the pathology described result in X% of IW's permanent disability at the time of his evaluation?
As to “pathology,” on what evidence do you rely that there was pathology pre-existing the industrial injury or occurring due to non-industrial factors after that injury?
What specific scientific studies or literature are you relying on?
You have referred to epidemiologic studies as showing that X can cause Y, but can you say with reasonable medical probability in this case that X caused Y?
Did the industrial injury light up the underlying asymptomatic degenerative disc disease to make IW symptomatic?

"But for" and Effect of Trauma:

"Could you say with reasonable medical probability that IW would have had any disability absent the industrial injuries he sustained while working for EMPLOYER?
"In the absence of the industrial injuries, can you say with reasonable medical probability that IW would have symptomatic and disabling arthritis in his knees?"
"If IW had not broken his right ankle in 1998 and spent the last eight years walking in an altered gait, could you say with reasonable medical probability that he would nonetheless have permanent disability in his right knee and the ankles?"

If he wouldn't have any disability but for the work injury, why isn't a hundred percent of the permanent disability due to the work injury?

"Lighting Up" of non-industrial, non-disabling, asymptomatic condition:

"Did [the trauma][his continuing to work] cause a non-industrial condition to be "lit up?" If so, would the non-industrial injury otherwise have remained asymptomatic and non-disabling? Was there an aggravation or acceleration of non-industrial conditions?"

Contralateral limb: Is there equal permanent disability in the uninjured limb? If apportioning to pre-existing asymptomatic pathology, would it not also affect the other limb?

Do-It-Yourself Medical Research:
Some Useful Links

Since revised Labor Code §4663 went
into effect, I have seen very few citations
to scientific studies in reports received
from Medical Evaluators, despite a request
in my letters such as this: "If you apportion
to pre-existing asymptomatic pathology or
risk factors such as age or obesity, please
state in detail the scientific underpinnings
for your opinion. What journal articles or
other evidence of scientific studies support
your conclusions?"

Don't leave it to the doctors to do the
medical research! There is a great deal of
information online. Google is a good place
to start in order to get general information
on the diagnosed condition and its causes.
See the sidebar for more specific medical

Insist that the physicians document their
opinions with medical citations, just as
lawyers have to do when they give legal

Don't leave it to the doctors to do the medical research!

"PubMed": "a service of the U.S. National Library of Medicine that includes over 16 million citations from MEDLINE and other life science journals for biomedical articles back to the 1950s. PubMed includes links to full text articles and other related resources.

Ex.: Search for "osteoarthritis with trauma with obesity with knee" yielded 38 hits

Wheeless' Textbook of Orthopaedics

The Med Engine:
http://www.themedengine.com/ index.html


Evidence-based Medicine ("EBM"):
This UK site has many useful links

getMedLegal.com's Medical Links: http://www.getmedlegal.com/wclaw/

Apportionment: Science or
Science Fiction?

With a new method ("IPECAC") for evaluating apportionment, some useful questions to smoke out bogus apportionment, and links for quick and dirty medical research.

By Marjory Harris
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