Effects of Medication and Impairment Rating

How the AMA Guides 5th Edition approaches impairment is complex, and accurate impairment ratings are tricky as a result.

For example, many medical providers don’t realize that the effects that medication has on an injured worker can actually change the worker’s impairment rating. This is defined on page 600 of the AMA Guides.

With page after page of definitions and tables, little details like these can easily be glossed over. We designed RateFast so that you don’t need to spend your time reading and re-reading the Guides. If you use RateFast to write your California PR-4 reports, then our software will prompt you with easy-to-answer questions about the effects that medication has on your patient.

But it’s still important to understand how the effects of mediation impact a worker’s whole person impairment. Here are a few key facts:

  1. “Effects of medication” are defined on page 600 of the AMA Guides, 5th Edition: “Medications may impact the individual signs, symptoms, and ability to function.”
  2. If an injured worker is affected by the medication he or she takes for the work-related injury, then the physician may choose to increase the impairment by small amount—between 1% and 3%. (Frustratingly, the AMA Guides do not give specific instructions on how to do this.)

So imagine that your patient has reached MMI for an injury to the low back. Let’s say that she is assigned a DRE category II and given a 5% WPI.

Now, imagine that the muscle relaxant she has been prescribed causes excessive drowsiness and limits her ability to drive. Is she eligible for an increased whole person impairment rating? Yes. The muscle relaxant has affected her life by limiting her ability to drive.

The moral of the story: if you’re a medical provider, make sure to ask your patients if their medications cause any side effect. It could make a real change in their impairment rating.

If you need help remembering to ask if medications are affecting your patients symptoms, try RateFast today for free. This question is built into our patient history questionnaire and our impairment calculations.

Increase Your Impairment Rating Accuracy

Understanding impairment is essential to workers’ compensation cases. Without a working definition of how the AMA Guides approaches impairment, accurate impairment ratings are impossible to assign or review. If you are working in the world of California workers’ compensation then you understand how complex impairment rating can be.

If you don’t have a thorough knowledge of how ratings are assigned in accordance with the AMA Guides then the accuracy of your permanent and stationary reports may be suffering. This leads to delays in patient care as well as extra work for you and your staff. 

Impairment severity, functional limitations and regional impairments… there’s a lot to wade through. Fortunately there’s a simple explanation for all of these moving parts. To learn more about the whole body approach to impairment simply follow RateFast’s easy walkthrough. How does the AMA guides fifth edition approach impairment? There are only 6 facts to keep in mind:

  1. The impairment severity reflects resulting in functional limitations.
  2. Most chapters report impairment as a whole person impairment units.
  3. Upper and lower extremity chapters have a regional impairments to assign additional weighted value to the specific areas of the arms and legs.
  4. Chapter 16, the upper extremities report sub impairment at the levels of digits, hand, and upper extremity.
  5. Chapter 17 the lower extremities report sub impairment at the levels of foot and lower extremity.
  6. Regional impairments of the spine are weighted accordingly to contribution of function.

So let’s say there’s a 52-year-old right-hand dominant labor worker sustained an amputation to his right thumb at the MP joint (40% HI), and the right small finger at the MP joint (10% HI).

Why is there such a big difference in impairment values? Using the organ system and whole body approach to impairment, the thumb is given four times the value as the little finger for functionality importance. Remember, The Guides 5th edition gives relative weights to organs and body systems. A keen understanding is critical to creating and reviewing accurate and reproducible impairment reports

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How to Request Authorization for Treatment

If you are a medical professional working in California workers’ compensation, then you will probably need to prescribe treatment or diagnostic testing for your patients.

When you’re working in California work comp, all treatment, testing, and other medical services must be authorized by the employer’s insurance administrator. To request authorization, you need to submit a Request for Authorization (or RFA). The RFA is a written request for treatment, diagnostic testing or other medical services for the injured worker.

Anybody can fill out a form. But it takes a true professional to complete an RFA form with all the information that insurance administrators need.

If you don’t complete an RFA form correctly, then your treatment authorization may be delayed, or not approved at all.

But you can easily submit a RFA that will give insurance administrators all of the information they need. You just need to cover all the bases by following a few simple steps.

How to Correctly Submit a Complete RFA in 8 Easy Steps

  1. Get the correct RFA form from the DWC website, here: https://www.dir.ca.gov/dwc/DWCPropRegs/IMR/IMRFormRFAClean.pdf

  2. In the top box of the form, check the reason for the RFA.

    • Check “New Request” for all treatment that you have not previously requested.
    • Check “Resubmission – Change in Material Facts” if new information is available about the employee’s medical condition.
    • Check “Expedited Review: Check box if employee faces an imminent and serious threat to his or her health” if the request is urgent–but not life threatening. (If the request is life threatening, and the employee requires hospitalization or emergency surgery, then submit a concurrent RFA.)
    • Check the “Check box if request is a written confirmation of a prior oral request.” if you have spoken with the claims adjuster, and you have agreed that the employee needs care and that the treatment will be approved. For example, if the employee requires immediate surgery or medication, and the adjuster verbally approves the treatment, you will still need to submit an RFA.


  3. Complete the rest of the form by providing basic information about the injured worker.

  4. In the “Requested Treatment” section, ensure that you give all details about the treatment you’re requesting in the “Other” column. For example, if you’re requesting physical therapy, then make sure that you indicate the amount of treatments; if you’re prescribing medication, then specify the dosage and refills.

  1. If you’re the treating physician, then sign the RFA. If you’re not the treating physician, make sure you get his or her signature.

  2. Submit the Request For Authorization form with the visit report (the Doctor’s First Report, PR-2 report, etc.) via fax or email. If you don’t submit the RFA with the visit report, then the RFA will likely be returned to you.

  3. You should receive your approved or denied RFA within 14 calendar days after you submit it. If you don’t, then contact the insurance administrator.

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What is the technical definition of disability?

Whether you’re a doctor, an attorney, or an insurance adjuster, a precise definition of disability is essential in impairment rating. However, for such an important term its technical definition often goes unexamined.

What You Need to Know About Disability

  1. Disability is an inability to meet social, occupational, personal, or statutory requirements because of impairment.
  2. Disability is different than impairment.
  3. Someone may have disability at home but not at work. Likewise, an individual may have disability at work, but not at home.
  4. A physician may provide an opinion on disability if he/she has expertise and is acquainted with the individual’s work activities and activities of daily living.
  5. An impairment evaluation is only one aspect of determining disability. A disability evaluation includes information about skill, education, job history, adaptability, age, environment requirements and modifications.

Time for an Example

Consider this: a 43 year old man performs sedentary clerical work. He has a permanent impairment from an amputation of the right leg below the knee. He cannot climb stairs in his home. Is he disabled from occupational demands? No. He performs clerical work that doesn’t require him to walk around. Is he disabled from personal demands? Yes! His activities of daily living are affected. Feel free to email us if you have any questions about disability and impairment rating.

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What is the technical definition of ‘Impairment’?

impair (v.) l, from Old French empeirier, from Latin impeiorare “make worse.” In reference to driving under the influence of alcohol, first recorded 1951 in Canadian English.

Okay…. But what does Impairment mean in the world of Workers’ Compensation?

If you’re a medical professional who examines injured employees, then impairment means “a loss, loss of use, or derangement.” (That’s straight out of the in the AMA Guides 5th Edition, Chapter 1, page 2.)

An injured worker’s impairment is considered permanent when the injury reaches “maximum medical improvement” or “MMI”.

Maximal medical improvement means the patient’s condition is unlikely to change in one year.

The AMA Guides 5th edition refers to impairment as permanent impairment. Permanent impairment requires evaluation of a physician.

Remember, loss, loss of use, or derangement means a change from normal.

So, let’s take this example: imagine a 27-year-old construction worker who has injured her right shoulder. At MMI, you as a doctor, measure the injured shoulder, which flexes to 160°, and then you measure the uninjured shoulder, which comes out to 180°. Does this patient have impairment?

The answer yes, because the employee has lost 20° of use.

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Understanding Exacerbation versus Aggravation

Exacerbation: from exacerbate. ex·ac·er·bate. iɡˈzasərˌbāt/
verb 1. make (a problem, bad situation, or negative feeling) worse.

Aggravation: from aggravate. ag·gra·vate ˈaɡrəˌvāt/
verb 1. make (a problem, injury, or offense) worse or more serious.

The difference… is confusing. That’s why we’re here to help! In a workers’ compensation context, the difference between exacerbation and aggravation is very significant.
  • Aggravation is a worsening of a pre-existing condition or impairment.
  • Exacerbation is a temporary or transient worsening of a prior condition.
  • The determination between aggravation and exacerbation can only be judged correctly when the employee’s work-related injury is at MMI (maximal medical improvement).

Problem Solving: A 34-year-old female has pre-existing chronic low back pain 5/10. Then, a work injury occurs, and the pain in her back increases to 8/10. Conservative care is provided, and at maximal medical improvement the pain returns to a 5/10.

Has an aggravation or exacerbation occurred?

The answer: Exacerbation, because the employee has returned to her pre-existing condition baseline.

Next time you need to look up this pesky but important difference, simply remember that the determination between aggravation or exacerbation can only be made at MMI.

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Do you have all the tools you need to perform an impairment exam?

Doctors can’t calculate an accurate impairment rating without the proper tools. Here at RateFast, we’ve reviewed a lot (a lot) of impairment ratings, and in our experience, one reason why doctors produce incorrect unjustifiable ratings is because they did not take the necessary measurements.

Accurate impairment ratings require accurate measurements, and to get the right measurements, you need the right tools.

Tools to Calculate Impairment Ratings

  1. Height and weight scale and blood pressure cuff — You need basic measurements and the worker’s basic vital signs.
  2. Tape measure — Made of flexible material, like fabric.
  3. Goniometer — Used for measuring joint ranges of motion. We prefer using goniometer apps on our phones. If you have an Android phone, you can download the RateFast Simple Goniometer for free from the Google Play store. If you have an iPhone, check the Apple App Store soon!
  4. Inclinometer — An inclinometer is used to measure the spine ranges of motion. You can also use use two phone goniometers, or one digital master/slave inclinometer.
  5. Grip dynomometer — Here in California, this is only for pain-free cases, greater than one year from date of injury or surgery.
  6. Pinch dynomometer — Like the grip dynomometer, this is only for pain-free cases, greater than one year from date of injury or surgery.
  7. Monofilament set — Be sure to have a 10 gram member in the set.
  8. Two point nerve discriminator — You can use a bent paperclip measured to 6 mm distance.

That does it. Once you get these tools, you’ll be ready to gather the correct measurements for your impairment ratings like a pro.

What about the rating itself?

Of course, to actually calculate the impairment rating in California (and many other states), you’ll also need the A.M.A. Guides 5th Edition. Then, you’ll need some time to plow through all the tables, diagrams, and charts.

Alternatively, you can join RateFast, and let our impairment rating specialists calculate the rating for you.

How to Measure and Report Ratable Atrophy According to the AMA Guides, 5th Edition

If you’re a medical provider, then at some point in your career you will probably observe atrophy in one of your workers’ compensation cases. We hope this post is useful for you if one of your patients has atrophy that is related to a work injury.

Muscle atrophy is a medical term that is used to describe the loss of muscle size or mass when concerning orthopedic injuries or conditions. For more on the definition of atrophy, click here.

Today, we’re discussing ratable atrophy, as defined by the AMA Guides, 5th Edition.

According to Chapter 15, The Spine (page 382), ratable atrophy in the spine requires a 1 centimeter (cm) difference or greater in the arm, forearm or leg (calf), and 2 cm or greater in the thigh.

Chapter 17, The Lower Extremities, page 530 Table 17-6 allows rating values to be assigned for 1 cm or grater for the thigh or calf.

Make sure muscle atrophy measurements are reported in centimeters. If they are entered in inches, convert and round the value to the nearest centimeter (cm).

Make sure that ratings assigned for muscle atrophy are reported and provided for the injured side.

Make sure that you’re using the correct chapter (Chapter 15, The Spine or Chapter 17, The Lower Extremities) when impairment values for thigh muscle atrophy are being assigned. If you don’t use the correct chapter of the AMA Guides when assigning ratable atrophy, then the impairment rating will be wrong!

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How to Calculate an Impairment Rating for a Skin Condition

Does Impairment Rating Get Under Your Skin?

Today we Chapter 8 in the AMA Guides 5th Edition: “The Skin.” Specifically, we want to make sure that you place a skin condition in the appropriate class for impairment rating.

The rating table, found on page 178 of the Guides, represents the rating strategy for the entire “Skin” chapter. The rating method is a class based rating system comprised of 5 classes. The whole person impairment range for the chapter is 0-95%.

The rating method in this chapter is primarily driven by the impact of the skin condition on activities of daily living (ADL;Table 1-2 Page 4).

Inventory the Activities of Daily Living!

Initial classification of the skin condition is based on determining how many ADLs (activities of daily living) are “limited.” The ADLs that are considered to be limited by the industrial injury or condition are then grouped into the following categories:

  1. No (none)
  2. Few
  3. Many
  4. Most

Classes 3 and 4 are differentiated by “intermittent confinement at home or domicile.”


When creating or reviewing an impairment rating for the injured employee’s skin, make certain the ADLs have been properly reviewed. It is necessary that those ADLs used to classify the rating category clearly are indicated as “limited.” When “Many” ADLs are reported as “limited,” a statement should be included if the condition results in the individual being confined to his or her home.

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What exams are included in the RateFast application?

In order to guarantee accurate impairment ratings and truly complete work-comp reports, the Ratefast app guides users through various medical examinations according to the requirements of the AMA Guides.

RateFast asks questions, prompts you to indicate abnormalities, and requests that you take measurements based on your patient’s injury. A set of these questions and prompts for measurements are called exams.


RateFast currently has customized exams for injuries to the following body parts:

  • AMA Guides 5th edition cervical spine exam
  • AMA Guides 5th edition thoracic spine exam
  • AMA Guides 5th edition lumbar spine exam
  • AMA Guides 5th edition shoulder exam
  • AMA Guides 5th edition elbow exam
  • AMA Guides 5th edition wrist exam
  • AMA Guides 5th edition thumb exam
  • AMA Guides 5th edition index finger exam
  • AMA Guides 5th edition middle finger exam
  • AMA Guides 5th edition ring finger exam
  • AMA Guides 5th edition little finger exam
  • AMA Guides 5th edition pelvis/hip exam
  • AMA Guides 5th edition shoulder exam
  • AMA Guides 5th edition knee exam
  • AMA Guides 5th edition ankle/foot exam
  • AMA Guides 5th edition toe exam
  • AMA Guides 5th edition skin exam (for various skin areas)

Related Reading

If you’re a current RateFast user and you want to learn how to access the body part exams, then check out this article in the How to Use RateFast – Basic Tasks section.

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