How Impairment Ratings Are Determined
When someone suffers a serious injury, whether from a car accident, workplace incident, or another traumatic event, recovery often involves more than just medical treatment. If that injury leaves lasting effects, especially ones that limit physical or mental abilities, an impairment rating may come into play.
This rating plays a key role in determining how much compensation an injured person may receive, particularly in workers’ compensation injury or long-term disability claims, and understanding how it works can help you better navigate this often confusing part of the recovery process.
What Are Impairment Ratings?
An impairment rating is a medical assessment of the degree to which a permanent injury affects a person’s bodily function. Doctors assign this rating as a percentage, which reflects the level of loss in physical or mental capacity.
For example, a 10% impairment rating suggests a person has lost 10% of their overall physical ability due to an injury.
This rating doesn’t necessarily measure how the injury impacts a person’s ability to do a specific job. Instead, it provides an objective estimate of how the injury affects general bodily function. In many systems, especially in workers’ compensation cases, the impairment rating is tied directly to the calculation of permanent disability benefits.
The Role of Medical Guidelines
Doctors don’t determine impairment ratings based on guesswork. Instead, they rely on established medical guidelines, most commonly the American Medical Association’s Guides to the Evaluation of Permanent Impairment.
These guidelines have detailed instructions on how to evaluate impairments for each body system, from musculoskeletal issues to neurological and psychological conditions.
Healthcare professionals use these guides to conduct standardized tests, measure range of motion, review imaging studies, and evaluate clinical symptoms. The guidelines include tables, charts, and formulas that help ensure consistency.
While these tools aim to promote objectivity, two doctors evaluating the same person might still come to slightly different conclusions, especially if the injury falls into a gray area.
How the Evaluation Works
Once the patient reaches maximum medical improvement (MMI), when their condition has stabilized and further treatment isn’t expected to significantly improve function, a physician can assess their impairment.
At this stage, the evaluating doctor will conduct a thorough examination. The process often includes strength testing, range of motion measurements, pain evaluation, and medical history review.
For example, if a worker is suffering from a repetitive stress injury, the doctor might check flexibility, muscle strength, and nerve function. They may also look at MRI or X-ray results. The doctor will then refer to the relevant section in the AMA guides to translate those findings into a percentage impairment rating.
This rating typically applies to a specific body part or system, like a hand, knee, or spine. In some cases, that partial rating is converted into a whole-person impairment rating to reflect the injury’s impact on overall function.
The method of conversion varies depending on the system used in the jurisdiction.
Impairment Ratings in Workers’ Compensation
Impairment ratings matter most in legal and insurance contexts. In workers’ compensation cases, the rating helps determine how much a person should receive in permanent disability benefits. States use different formulas, but the general idea is that higher impairment ratings lead to greater compensation.
Some states categorize injuries as either scheduled or unscheduled. A scheduled injury involves a body part listed in a statutory schedule, such as an arm or leg. Compensation for those injuries is often calculated based on the percentage of impairment and the number of weeks assigned to that body part.
Unscheduled injuries, such as back injuries or traumatic brain injury, are evaluated differently and may consider other vocational factors, along with the impairment rating.
Disputes and Second Opinions
Disagreements sometimes arise because impairment ratings can significantly affect the amount of compensation someone receives. An injured worker might believe the rating is too low, while an employer or insurance company might argue it’s too high.
When that happens, parties can request an independent medical evaluation (IME) or a second opinion from another doctor.
In some jurisdictions, a neutral physician appointed by a state agency may perform the exam to ensure fairness. The findings from an IME can support a legal case, especially if the worker appeals against a benefits decision. Workers should keep in mind that an impairment rating is not always final—if the condition worsens or improves, the rating may be revised.
Impairment vs. Disability
It’s easy to confuse the terms “impairment” and “disability,” but they serve different purposes.
An impairment rating reflects a medical judgment about loss of function without considering how the injury affects someone’s ability to work. Disability, on the other hand, includes practical considerations like job duties, skills, education, and the labor market.
A person may have a low impairment rating but still be unable to return to their old job, especially if it requires physical labor.
At Work Injury Advisor, we understand how impairment ratings are determined, as well as related federal laws and regulations, and we can help injured individuals advocate for fair treatment.
Whether navigating a workers’ comp claim or applying for long-term disability insurance, knowing what to expect from the process—and how to respond to low ratings—can improve your outcome.
Let us know if we can help.
