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Workers' Compensation Impairment Rating

Adopted from the AMA 5TH GUIDE for Teaching Purposes

By Nachman Brautbar, M.D.


Maximal Medical Improvement = MMI
The impairment is permanent and stabilized and unlikely to change substantially in next year with or without medical treatment.

The general concept is a definition which describes activities or functions, which have been changed or not, as a result of an injury or illness. It can be used for disability [U.S. Social Security, World Health Organization].

Evaluating an Individual
"The physician should use clinical judgment regarding normal structure and freedom and estimate what is normal for the individual based on the physician's knowledge or estimate of the individual's pre-injury or pre-illness condition."

This concept is very important to understand when the physician qualifies an impairment at a certain range, and has to choose a number out of that range; i.e. 10-18% whole person impairment. What will make it 10% or 12% or 18%? One of the criteria is the clinical judgment of the physician, and no one else but the physician! Other factors such as activities of daily living "ADL", are also important to assess the range.

So that if disagreement might arise on the rating of impairment, an AME or a court appointed physician will decide. For example, 40-60%, one physician feels it is 40%. On the other hand, clinical judgment, ADL tend to support 50%.

Physician's Role In Impairment Rating,
Workers' Compensation System

A medical appraisal of the nature and extent of the injury or disease as it affects an injured employee's personal efficiency in the activities of daily living, such as self-care, communication, normal living postures, ambulation, elevation, traveling and nonspecialized activities of bodily members.

Impairment Percentage Or Rating

Impairment percentages or ratings developed by medical specialists are consensus-derived estimates that reflect the severity of the medical condition and the degree to which the impairment decreases an individual's ability to perform common activities of daily living (ADL), excluding work.

Impairment ratings were designed to reflect functional limitations and not disability. The whole person impairment percentages listed in the Guides estimate the impact of the impairment on the individual's overall ability to perform activities of daily living, excluding work, as listed in Table 1-2.

Table 1-2

Activities of Daily Living Commonly Measured in Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) Scales


Self-care, personal hygieneUrinating, defecating, brushing teeth, combing hair, bathing, dressing oneself, eating. 

CommunicationWriting, typing, seeing, hearing, speaking. 

Physical activityStanding, sitting, reclining, walking, climbing stairs. 

Sensory functionHearing, seeing, tactile feeling, tasting, smelling. 

Non-specialized hand activitiesGrasping, lifting, tactile discrimination. 

TravelRiding, driving, flying. 

Sexual functionOrgasm, ejaculation, lubrication, erection. 

SleepRestful, nocturnal sleep pattern. 

Impairment (ADL) V. Disability (Work)

Thirty percent (30%) whole person impairment secondary to a heart condition, does not automatically equate to 30% disability [if the job is sedentary, then the 30% may not be a major disability. On the other hand, if the job is that of a mover, then 30% will take him out from his regular job, to 100% disability (AMA page 5). Therefore, the physician should, in addition to impairment rating, opine on limitations or ability to go back to a certain job]. So that I always opine: Impairment and work restrictions.

Impairment And Work Restrictions

Example: Asthma in a spray painter.

The patient qualifies for Class 2 AMA 5th Guide, page 104, Table 5-10, for 10-25% whole person impairment. Based on the records [recurrent asthma and visits to the company clinic [and ADL: shortness of breath, severe, climbing stairs] the patient qualifies for 20% whole person impairment.

He should not be returning to a work environment where exposure to fumes, dust and bioaerosols over the ambient background is expected (AMA 5th, page 5).

The AMA Guide does not cover all conditions. Therefore, the Guides state, "in situations where impairment rating are not provided, the Guides suggest that physicians use clinical judgment, comparing measurable impairment resulting from the unlisted condition to measurable impairment resulting from similar conditions with similar impairment of function in performing activities of daily living."

Therefore, the physician must use sometimes extrapolation from similar conditions.

Your Evaluating / Treating Doctor Must:

  • Address ADL
  • Perform a detailed history
  • Detailed physical evaluation.
  • Basic and follow up vital signs (weight, B/P)
  • Inquire about chronicity of medications
  • Sleep patterns
  • In chronic musculoskeletal injuries, refer to an internist

Now that we understand some basics, let us see how the Guides apply to internal medicine and toxicology. Study these examples to master the Guides.

Hypertension & Diabetes, Stress Related

Fifty-year-old, hypertensive, diabetic. Hypertension requires three medications, diabetes is type II, needs diet, medication and exercise. [Assumption for purposes of today's talk: Causation AME/COE: accepted injury, apportionment not discussed today]. So we have here three regions to address, in this patient:

So that in this case, blood pressure is 160/100, requires medication and has proteinuria. Per Table 4-2, he qualifies for 30-49%. So is it 30, 40 or 49%? His ADL indicate that none of the criteria is impaired. Records do support an uncontrolled blood pressure despite medications. He already has end organ damage, which is already addressed in Class 3 Table 4-2, he qualifies for 30% WPI.

Based on Table 10-8, he qualifies maximally to 10% [type II diabetes]. Since he requires medications and diet, but his ADL are not altered he will qualify for 6% WPI.

Combined Impairment Ratings
Now we need to take the combined impairment rating table, which will bring the whole person impairment to 32% in this case.

The report in this case will say:
Impairment And Work Restriction

The patient is MMI. It will explain the steps I took to derive the figure of 32%. I will also state: The patient should not work in an environment with heavy public contact, firing and hiring people, because his blood pressure and diabetes are out of control and stress-related, with already end organ damage (proteinuria).

Let us take the same case with some changes.

Hypertension, stroke, diabetes type I, sexual dysfunction severe (ADL table).

So, now we have four regions: Hypertension, diabetes type I with frequent hypoglycemia, stroke with residuals, gait impairment and speech impairment, and sexual dysfunction.


Based on the data in Table 4-2, hypertension requiring medications and still uncontrolled, stroke secondary to hypertension, he qualifies for class 4: 50-100% impairment. Based on severity of ADL, the speech impairment and gait impairment, he qualifies for 100%. What about sexual dysfunction? Yes, it is ratable, but post SB899, an injured worker cannot reach more than 100%. For teaching purposes, let us study the other regions of impairment in this patient.

Diabetes Mellitus
In this case, the patient qualifies for class 4, 21-40% impairment. There is frequent hypoglycemia with good compliance, patient qualifies for 30% WPI. (Diabetes Table 10-8)

Sexual Dysfunction
In reliance on the ADL, history given, no sexual function, he qualifies for 20% whole person impairment. (Sexual Dysfunction Table 7-5)

Failed Back with Chronic Pain

Let us move now to a very common segment of the injured workers: Failed back with chronic pain [assumption for today's discussion, accepted back injury].

A 40-year-old, failed back (3 surgeries in 1997, 1999, 2002) developed high blood pressure [compensable consequence], abnormal EKG, sexual dysfunction, kidney disease, biopsy proven compatible with phenacetin and medication induced.

So here we have to address: 1) Hypertension with left ventricular hypertrophy; 2) sexual dysfunction, 3) medication induced nephropathy with a creatine clearance of 40 ml/hr.

He qualifies for Class 3 30-49% [hypertension over 160/100 and left ventricular hypertrophy]. In this case, since none of the ADL seems to be affected by this condition, the whole person impairment is 30%. (Hypertension Table 4-2)

Sexual Dysfunction
In this case, baseline ADL qualifies for 20% whole person impairment.(Sexual Dysfunction Table 7-5)

Kidney Disease
In this case, he qualifies for 35-59% whole person impairment. Based on ADL, he will qualify for 35%. [None of his ADL other than sexual functions are addressed].(Kidney Disease Table 7-1)

Based on the combined impairment table, whole person impairment [internal medicine and toxicology], 30% + 20% + 35% = 51% whole person impairment.

The report will explain how I derived 51%, each step, each table. I will also opine that the patient should not be exposed to emotional stress [hypertension, chronic pain syndrome].

The most commonly missed ratable compensable consequences are:

  1. High blood pressure
  2. Sexual dysfunction
  3. Kidney disease from medications
  4. Liver disease from medications
  5. Sleep disorders (pain and medications)
  6. Substantial weight gain
  7. Heart disease

There is no excuse for the physicians rendering care for these patients not to measure blood pressure, not to do a chemistry panel, blood count and urine analysis [failed back, chronic pain].


Spray painter, 35-year-old [5 years] asthma, requiring medications, [accepted as an industrial injury]. The treating physician notices abnormal liver functions, liver biopsy: Non-alcoholic liver cirrhosis [assume all other causes for liver diseases have been ruled out]. While on asthma medications, patient is prescribed prednisone 30 mg for one month, throughout the years, asthma not controlled and FEV is 48%. He develops gastric ulcers [endoscopy proven] and bone osteoporosis [severe]. At home, while getting out of bed, the patient fractures a vertebra. So now we have: 1) Asthma, 2) liver disease, 3) gastric ulcers, 4) osteoporosis and bone fracture.

In this case, we have impairment class 4, qualifying for 51-100% based on ADL qualifies for 80% WPI [ambulation, sleep].(Asthma Table 5-10)

Patient qualifies for class 3, 25-49% WPI. Based on ADL, inability to eat without pain and nausea, patient will qualify for 35% WPI. (Gastric Table 6-3)

Liver Disease
He qualifies for class 2 WPI 15-29%. Based on the advanced liver disease (biopsy), and the extreme fatigue affecting ADL, WPI of 20%. (Liver Disease Table 6-7)

Based on the combined impairment chart from an internal medicine/toxicological impairment: 80% + 35% + 20% = 86% WPI.

The metabolic bone disease (osteoporosis) caused by steroids is ratable, but requires range of motion and therefore an orthopedic consult for the specific range of motion secondary to osteoporosis fracture is required. This will be added to the WPI.

The report in this case will say:
Impairment and Work Restrictions:

Explaining the WPI of 79% the potential added on impairment from osteoporosis. Impaired, nevertheless, taking into account his severe asthma, weight gain of 75 pounds, secondary to steroids, severe osteoporosis and risk of more bone fractures, practically the patient is not fit for employment. Now, this may not grant 100% impairment, but the raters will clearly look at this recommendation.

The most commonly missed issues in toxic exposures (solvents, painters, mechanics) are:

  1. Failure to evaluate liver and kidney potential effects.
  2. Failure to evaluate potential peripheral or central nervous system effects.
  3. Secondary cardiac effects [75 pound weight gain, from steroids, direct toxicity of solvents, secondary effects of lung disease on the heart].

Toxic Exposure

This is a 40-year-old city maintenance worker with 15 years daily exposure to solvents, paints and pigments containing chromates and isocyanates. He developed shortness of breath and flare up of prior pemphigus of the skin. His physician diagnosed asthma and pemphigus vulgaris with constant skin rashes, ongoing need for medications. Since the asthma and pemphigus deteriorated, he has been on disability mainly at home secondary to severe skin rashes.

He has gained 50 pounds secondary to steroids, and developed sleep disorder, diagnosed about 2 years ago by certified sleep study experts as severe. The patient developed tingling sensation of the extremities, and loss of sensory capacity of upper and lower, and peripheral neuropathy secondary to solvents was diagnosed. The patient's ADL was assessed as follows:


Self-care, personal hygieneUrinating, defecating, brushing teeth, combing hair, bathing, dressing oneself, eating. 

CommunicationWriting, typing, seeing, hearing, speaking. 

Physical activityStanding, sitting, reclining, walking, climbing stairs. 

Sensory functionHearing, seeing, tactile feeling, tasting, smelling. 

Non-specialized hand activitiesGrasping, lifting, tactile discrimination. 

TravelRiding, driving, flying. 

Sexual functionOrgasm, ejaculation, lubrication, erection. 

SleepRestful, nocturnal sleep pattern. 

Asthma Exercise testing showed VO2 max if < 4.3 mets.(Asthma Table 5-12)

Patient qualifies for class 4, 51-100%, based on ADL 60%.

Based on ADL constant symptoms and constant treatment Class 4, 55-84%, baseline ADL 70%. (Skin Table 5-12)

Peripheral Nervous System
Based on the loss of sensory feelings, and NCV studies of upper extremity functions, class 3, 25-39% whole person impairment. (Nervous System Table 13-16)

Based on ADL 30% based on the combined impairment rating table, 70% + 60% + 30% = 84% WPI.

In my report, I will also recommend neurocognitive and psychiatric evaluation. I will also request sleep studies, by a certified expert since most recent ones were some 2 years ago.

From a practical point of view, since this patient insists on working (computer science), he should be accommodated at this level.

Dr. Brautbar is a board-certified internist and nephrologist, and certified in forensic medicine. If you are interested in retaining Dr. Brautbar for forensic and expert witness testimony services, please submit the Contact Form.

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