AMA Guide 4th Edition evaluation of permanent impairment handbook

A very loyal reader and good friend of ours has come across and so kindly shared the User Handbook to the AMA 4th Edition Guide to the Evaluation of Permanent Impairment, which is still used in many states to assess how the whole person impairment is calculated.

AMA Guide 4th Edition evaluation of permanent impairment handbook

Permanent impairment and lumpsum

You may be entitled to a lump sum payment if you are left with a permanent impairment because of your work injury. Unlike a common law damages claim, this is a no fault benefit, so you do not need to establish that your employer has been negligent.

The benefit is calculated in accordance with a formula depending on the level of impairment you are assessed as having. An independent doctor would need to examine you in accordance with a guide published by the American Medical Association (In Victoria and some other Australian states it is the 20 year old 4th edition).

The criteria for entitlement to a lump sum claim are tough and claims can be rejected by WorkSafe. The best rule if you are considering making a lump sum claim is therefore to get legal advice.

As a general rule, you must have suffered 10% physical permanent impairment as assessed by WorkSafe Vic (sometimes 5% for certain injuries like arm, leg, back). Here’s a rough guide:

5% impairment: $10,760
15% impairment: $32,348
20% impairment: $44,745
25% impairment: $57,143
30% psychiatric impairment: $69,540

Though? Yeah…real tough!

At first glance one would think that we have a what appears to be a reasonable, standard “guide” in place (The AMA guide 4th Edition) to assess the level of permanent impairment for each injured person…


… you will soon realise (if you dig a little further) that the use of the AMA guide (4th Edition) is based on pseudo science and designed to do only one thing: to stop people — especially the most vulnerable  — from being fairly compensated.

Did you know that the AMA Guides 4th Edition were published in 1993,they are just about 20 years old!

Under the current workers compensation system the kinds of injuries that would be denied compensation include:

  • vertebral fractures resulting in up to 25% compression with ongoing pain : 5-8% total body impairment rating!
  • spinal fusion requiring multiple surgeries with ongoing pain : up to 14%
  • surgically treated disc lesion with ongoing pain: 10%
  • pelvic fractures with displacement deformity: 2-10%
  • disorders restricting ability to walk up mild gradients and stairs, sit down in deep-chairs, rise to a standing position or walk long distances 1-9%
  • brief repetitive or persistent alteration of state of consciousness or awareness 0%-14%
Blame the lump sum culture eh… for the scheme’s deficits… what “lump sum”?

In NSW the new draconian compensation law now also states that lump sum payments are only available for serious permanent injuries, which are defined as greater than 10% WPI.

In Victoria (and most other states) Impairment benefit compensation is determined in accordance with a formula set out by law, dependent of the level of impairment you are assessed as having and the date of your injury. Once the level of impairment is accepted, you cannot negotiate on the amount of compensation that you are entitled to.

To receive any compensation for a psychiatric injury, you need to be assessed as having at least a whopping 30% whole person impairment (primary psychiatric injury).

You may only bring a lump sum claim once your injury has stabilised (that is, not getting any better or worse). At a minimum, you need to wait at least 12 months since your date of injury.

AMA Guide 4th Edition

This handbook to the AMA “Guides to the Evaluation of Permanent Impairment” 4th Edition is from New Zealand, but they too are based on the AMA 4th Edition & the worksheets & descriptions of how the ‘whole person’ permanent impairment  is calculated may just help you to understand the system too!


Related articles


[Post entirely entered by T on behalf of workcovervictim who is suffering from yet another nasty shoulder dislocation… ]




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One Response to “AMA Guide 4th Edition evaluation of permanent impairment handbook”

  1. An interesting article on the editions of AMA impairment ratings.

    Possibly the 4th edition is the best edition to be assessed with.

    AMA Guides to the Evaluation of Permanent Impairment,
    The 5th and 6th Editions Comparison: a failed paradigm shift
    John E. Nimlos MD November 17, 2010
    Written testimony to the House Committee on Labor and Education,
    Sub-Committee on Worker Protection
    Executive Summary
    This presentation will show that the AMA Guides to the Evaluation of Permanent Impairment,
    Fifth Edition remains the preferred reference for impairment rating, as the 6th Edition is a
    disruptive document with many more disadvantages than improvements. Over the 10 years of its
    publication, the 5th Edition has effectively guided a national cadre of experienced physician
    raters. In contrast, the 6th Edition requires a complicated, multistep process for each rating. If the
    new, time-consuming process leads to better, more scientific, and more accurate ratings, it might
    be worth it. It does not.
    The 6th edition, despite making major changes to ratings, mostly downward, has no more science
    behind it than the 5th. In fact, there appears to be less science. Therefore, relying on the 6th
    Edition will lead to greater expense: training doctors, system adjustment to the new impairments,
    increased litigation, and increased wage replacement cost due to delays in claim resolution. In
    contrast, if the 5th Edition shows consistent problems in one or another area, and some rational
    science becomes available to address those, addenda can be added cheaply and efficiently.
    If there are multiple areas scientifically shown to need improvement, a “5th Edition-Revised” can
    be provided. Until such time, continued use of the AMA Guides 5th Edition generates no new
    expenses, can be adjusted to reflect new science if needed, and allows systems using the Guides
    to continue the adjudication decisions, standards, and adjustments already in place. The simple
    decision to retain the 5th Edition eliminates the considerable time and expense of dealing with a
    new system that has no proven value or reliability.
    I am a medical doctor specializing and board certified in Occupational Medicine. I treat
    employees for injuries and illness incurred in the workplace. For 24 years, I’ve examined
    workers under two different state workers’ compensation systems, as well as federal employees
    under the FECA and Longshore and Harborworkers programs. I make decisions every day about
    impairment, and disability.
    I am familiar with all editions of the Guides, and used the 3rd, 3rd (Revised), 4th, 5th and 6th to
    determine impairment ratings, as well as using Washington State’s impairment system. I have
    taught doctors about impairment ratings and explained ratings to patients for many years. I can
    AMA Guides 5th and 6th Editions John E. Nimlos MD CIME November 17, 2010 Page 2 of 6
    state that the 6th Edition is dramatically different from the prior editions, and as the authors say, a
    paradigm shift.
    Impairment and Disability are not the same
    These two words are frequently used interchangeably, but they actually have importantly
    different meaning. Impairment refers to a loss of function. It simply means, for example, that the
    grip is weak, or that the arm has less mobility. Disability refers to the effect of the impairment on
    the ability to perform a job or specific task.
    For example, I injured my shoulder years ago. My arm was so weak, I could hardly lift a gallon
    of milk, I couldn’t reach higher than the level of my chest. I was impaired. I could do all my
    work as a doctor, so I was not disabled. However, if I were a carpenter with the same
    impairment, I’d be both impaired and disabled. The AMA Guides to the Evaluation of Permanent
    Impairment have been in existence for 40 years and are used to rate the extent of impairment.
    Doctors’ impairment ratings a measurement of how much loss of function is present. It refers to
    limits to everyday living tasks, common to all people. Disability is how that impairment affects
    a person’s job. Impairment rating percentages are just the beginning of disability determination.
    Disability rating or compensation, depends on how each system applies its own rules and process
    to come to a monetary amount or qualification for benefits.
    The 6th Edition greatly increases the complexity of impairment ratings
    The 6th edition uses the same structure and method for all of the different body parts and
    systems. Though this is intended to make it more consistent, it also makes it difficult to fit the
    rating process to the rated part, and reduces the role of the examining doctor to best reflect the
    actual limitations for the claimant he or she is evaluating. In addition, because of this rigid
    adherence to structure, impairment ratings which are easy and straightforward under the 5th
    Edition are made needlessly complex.
    For 6th Edition ratings I charge extra; I find this methodology clumsy and extremely difficult to
    work with. Every rating under the 6th Edition takes several steps, regardless of how
    straightforward rating a patient could be. After the examination, plus a required patient
    questionnaire to score, the doctor first goes to a chart for the diagnosis. The diagnosis has a
    number associated with it. It also has a range from A through E, with C being the middle, and the
    default impairment rating that is meant to represent the average impairment for that diagnosis.
    Then he must find three other charts for 1) examination results, 2) test results, and the 3)
    claimant’s function. Applying estimates from “no problem” to “severe” in each chart, the doctor
    gets numbers from these three, and subtracts each number from the number assigned to the
    diagnosis, then adds those three results together. The result is added or subtracted from the
    number on the diagnosis chart. This sum is the number that determines how far up or down the
    narrow A though E range that determines the final rating, as adjusted from the average for that
    AMA Guides 5th and 6th Editions John E. Nimlos MD CIME November 17, 2010 Page 3 of 6
    By contrast, the 5th Edition rating requires physical examination and tests. With the medical
    information, he or she goes to a table for each measurement or claimant characteristic, and
    matches the claimant’s measurement or description with an impairment percent from the table.
    Sometimes there is more than one table, but even then, for most cases it’s not that difficult. With
    some guidance, many cases can be rated by an attending doctor. I’ve even given phone
    instructions to doctors, enabling them to do ratings successfully with the patient or medical
    record in front of them.
    The 6th Edition still uses consensus-based estimates for impairment rating that are no more
    scientific, and with non-medical factors now present in these estimates, there is even less
    medical science in this edition than previously.
    The 6th Edition is controversial for another reason. Though it claims to be, it is not really
    evidence-based. It produces impairment ratings far different from those in prior editions, most of
    them lower than before, it without adequate support for doing so. In the course of evaluation of
    the 6th Edition for the state of Iowa, Mr. Matthew Daker, and Dr. John Kuhnlein, the authors of
    both evaluations that I found for review also concluded with the advantage of author interviews,
    that there remained too many obstacles to effective and reliable ratings. The authors admitted
    that there was no more scientific evidence brought to bear in the 6th edition, and noted the
    influence of insurance and adjudicators in the adding of very low, once-in-a-lifetime ratings so
    that people could qualify as having impairments, perhaps a minimal response to requests from
    plaintiff groups for at least some recognition of conditions previously given zero impairment.
    I suspect that Dr. Brigham’s assertions that ratings are too high (his estimate at 8% too high) also
    had to do with the consensus estimates of the 6th Edition authors. Dr. Brigham’s assertions about
    the distortion of ratings are based on his own studies. The material from those studies are taken
    from his practice in reviewing ratings sent to him for analysis. Dr. Brigham’s advertisements
    appear clearly to focus on the defense (employer, workers comp insurer, defense attorney)
    population, so it is likely that the only clients who would be spending the $150 fee would be
    those for whom they thought would save that at least that amount by finding out about a rating
    suspected to be too high. In that setting, ratings too low, or that were appropriate would not
    likely show up in his numbers.
    In contrast to this, I have a series 401 consecutive independent medical examination (IME)
    reports received by me as attending physician, or reviewed by request from other physicians who
    my review of the IME’s to advise the doctors whether to agree or not with the report. In this
    series, I found that 45% of the IME’s were valid. The remainder had serious flaws, for a variety
    of reasons, one of them being incorrect impairment ratings. The majority of errors had to do with
    rating, and every rating but one was too low. Unlike Dr.Brigham’s study, mine was only
    selected by my presence in the case as attending physician, or were sent by physicians with only
    the interest in knowing the accuracy of the report, not by whether the rating was too high or low.
    In light of this, I question the validity of Dr. Brigham’s assertions about ratings too high. Dr.
    Brigham’s population suggested 89% of ratings to be too high. Another said that 78% of ratings
    AMA Guides 5th and 6th Editions John E. Nimlos MD CIME November 17, 2010 Page 4 of 6
    were incorrect, and again, too high. My study showed essentially 99% of ratings to be too low.
    My data are in agreement with another study of 17 patient ratings. Though the patient number
    was disappointingly low, this was the only one I could find in a literature search for peerreviewed
    reports on IME quality. It is a sad comment on the role of science in the AMA Guides,
    that I found more information about these issues in a Google search than I did by searching the
    medical literature by PubMed (The National Library of Medicine).
    Lastly, though the authors of the Guides do refer to evidenced based research in the 6th Edition,
    the only studies they could find were deemed unreliable for use as impairment rating
    information, and that further research was required. The only approach in the 6th Edition that has
    to do with evidence is the assertion that the diagnosis used for rating be made based on evidence.
    Perhaps this edition’s authors somehow believe that doctors making diagnoses for prior editions’
    were not based on evidence.
    Many of the 6th Edition ratings are different, with no explanation of why the rating is
    changed. Most changes are to a lower rating, some are far lower.
    With regard to medical reliability, there seem to be many unexplained rating changes in this new
    Edition compared with the earlier editions of the Guides. Questions arise about the ratings
    recommended by the Sixth Edition. For example, why is the impairment rating for a total knee
    replacement with “good” result 37% in the 5th Edition and 25% in the 6th Edition? Is that
    evidence based, as the 6th Edition purports to be? No, the rationale for this particular rating is, as
    expressed by Dr. Chris Brigham, Senior Contributing Editor for the 6th Edition, who has stated
    that the “improvement in medical technology” is the reason for the lower rating.
    Though this suggests that some science backs up the lower rating. However, the actual process
    of rating determination is different between the two editions. The 5th Edition appears to actually
    draw more upon science than the Sixth. In the 5th edition, the “good” rating is defined by a
    numerical score derived from several measurements, and used by orthopedic surgeons as a
    recognized standard for describing and categorizing knee replacement outcomes. In the 6th
    Edition, the “good” definition uses undefined degrees of outcome measures, e.g. “mild”, “good”,
    “severe” usw. These are imprecise at best, and subject to the judgment and/or bias of the
    The total knee replacement decrease in impairment is not alone. In my own analysis of ratings
    coming from the AMA’s publication by Dr. Chris Brigham, The Guides Casebook, 3rd Edition,
    selecting all the extremity ratings, as in Washington the Guides are prescribed for rating these,
    and a couple others due to their common occurance as rating questions. Of the total of 35 ratings
    examined, only 6 ratings went down in the 5th compared to the 4th Ed. Those ratings averaged
    less than one fifth (19%) lower than the 4th Edition. In contrast, 21 of 35 ratings go down in the
    6th compared to the 5th; 3-and-a-half times more ratings are made lower by the 6th Edition than
    were reduced in the 5th. And, in the 6th Edition, not only are more ratings reduced, but they are
    AMA Guides 5th and 6th Editions John E. Nimlos MD CIME November 17, 2010 Page 5 of 6
    made lower by an average of more than a two fifths (36%) – almost twice the magnitude of
    decrease amount of the impairment ratings.
    My analysis is not the only one that does this. Dr. Melhorn did an analysis of selected diagnoses
    comparing 5th and 6th edition ratings, demonstrating the rating averages to be lower for the Sixth
    edition, though at a less dramatic amount. However, if he’d gotten the arithmetic accurately, he’d
    had shown a more significant difference between the average rating in the 6th from the 5th than
    appears in his tables found in his article in the IAIABC Journal.
    Lastly, a large number of ratings, 52, were examined by Sedgwick Claims Management Services
    for the state of North Dakota involving extremities and spine as well as multi-injury cases. Six
    ratings were the same or slightly higher by the 6th edition. The other 46 ratings were lower, many
    much lower. On average by body region, ratings were 0.8% higher for ratings of the Hand to
    12.6% lower for the Cervical Spine. This does not mean that the rating was 12.6% lower as in
    lowered by about 1/8 of the rating, it means that the average rating went from 24.8% to 12.2%.
    These are very large differences. When compared in order of magnitude of initial 5th edition
    rating, the lowering of the impairment rating was much more dramatic as the 5th edition ratings
    that were higher. For ratings in the highest range, the average for 5th Edition was 67%
    impairment, in the 6th edition, the same cases averaged 44.7%. This is a decrease of nearly one
    Another study of 200 cases from Dr. Brigham was also reviewed showing many lower ratings in
    the 6th edition, in similar magnitudes. This is particularly interesting in light of my recall from
    Dr. Brigham stating that he did not think the 6th edition would result in many reduced ratings,
    and that whether or not it would remains to be seen. By virtue of his own recent report in The
    Guides Newsletter*, as cited by, and providing the above statistics from, in the Sedgwick report
    The Sedgwick report goes on to estimate that using the 6th edition. The conclusion was that
    North Dakota would save $1.1 million dollars in permanent partial impairment awards by
    adopting the 6th Edition. This was immediately followed by a statement that asserted, “The 6th
    Edition of the AMA Guides to the Evaluation of Permanent Impairment is the latest version of
    the Guides and is the result of the evolution of medical science as well as research based
    medicine.” As thorough as the report is in many respects, it appears the report authors did not
    investigate the assertion of science and research as the basis for the 6th edition, and were likely to
    convey to the decision makers for North Dakota an opinion that is not supported by the facts.
    It will be expensive and difficult to maintain an adequate population of qualified doctors
    for impairment ratings under the 6th Edition.
    In my home state of Washington, more ratings by attending doctors are desired. I know from my
    experience in encouraging primary and specialty doctors to do ratings for their own patients, that
    it is already difficult to get treating doctors to embrace impairment rating and the Guides. Most
    step back slowly if I bring out the book, but I believe they will run from the complicated,
    multistep arithmetic and rules of the 6th Edition. Doctors are quite familiar with the 5th Edition,
    AMA Guides 5th and 6th Editions John E. Nimlos MD CIME November 17, 2010 Page 6 of 6
    and the system has begun to find stability with the 5th Edition. The 6th Edition’s methods are
    dramatically different from the prior systems, and already throw controversy and error into
    systems relying on their use. Adding the 6th Edition’s untested, and unproven departure from the
    format used for the past 40 years, doesn’t seem worth the disorientation it will cause.
    6th Edition ratings take much more time, and likely will add to rating examination expense.
    Dr. J. Mark Melhorn, an orthopedic doctor from Kansas, a contributor to the 6th Edition Guides
    conducted an informal study on the time consumed in ratings. He found that 7 expert raters who
    teach other doctors how to use the Guides, doing identical sample cases, averaged 5 minutes to
    rate by 5th Edition, but to do 6th Edition ratings they averaged 25 minutes. Because of this
    additional time and hassle, I charge an extra fee for 6th Editions ratings that adds between 15 and
    20% to the cost of the examination. Other doctors who do ratings will need to pay for the
    additional training and certifications costs, and are likely to pass this cost along to their clients.
    Especially at the beginning, disagreement about ratings is likely to occur resulting in additional
    costs for IME’s and/or legal expense.
    Physician clinical judgment remains the hallmark of impairment ratings, it is greatly restricted in
    the 6th Edition, but with no science to back up that decision, or the altered ratings.
    Thus, it appears that the transition from the 5th to the 6th Edition shows much more pervasive
    and dramatic changes to ratings than previous edition changes. I believe that the previous edition
    changes generally provided improvements. The changes in the 6th edition are many and large. If
    adopted generally, the 6th edition of the AMA Guides will disrupt disablility systems, increase
    examination costs, increase litigation expenses and seriously threaten fair compensation for
    injured workers.
    In light of all these issues, I agree with the states of Iowa, Kentucky, Washington, Colorado,
    Utah and others, that the 5th Edition should remain in use, until something truly better comes
    * Brigham CR, Uejo C, McEntire A, Dilbeck L. Comparative Analysis of AMA Guides Ratings by the Fourth,Fifth,
    and Sixth Editions. Guides Newsletter. January – February 2010.
    Complete annotated bibliography will follow.

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