Impairment is a medical finding. Disability is a legal determination. They are produced by different parties, at different stages of a claim, using different methodologies, and they are not interchangeable. Conflating them is one of the most common errors in impairment rating reports, and it is one that opposing counsel will notice immediately.
What Is Impairment?
Impairment is a measurable reduction in the function of a body system, organ, or structure resulting from a medical condition, injury, or illness. It is expressed as a Whole Person Impairment (WPI) percentage, calculated by a licensed physician using the AMA Guides to the Evaluation of Permanent Impairment. Impairment is objective and standardized; the same injury, evaluated by different physicians using the same edition of the AMA Guides and the same diagnostic protocol, should produce the same or very similar WPI.
Impairment is permanent. It is assessed only after a patient has reached Maximum Medical Improvement (MMI), the point at which the condition has stabilized and no further recovery is expected. Before MMI, there is no basis for an impairment rating.
What Is Disability?
Disability is a legal and administrative determination about how a person's impairment affects their ability to work, perform activities of daily living, or function in their specific vocational and personal context. Disability is determined by state agencies, courts, and insurers, not by physicians. The physician produces the WPI. The system converts it into a disability determination.
The same 20% WPI will produce different permanent partial disability (PPD) awards in California, Nevada, and Texas. Each state applies its own formulas, multipliers, and schedules. Disability classifications also differ by context: workers' compensation, Social Security, VA disability, and long-term disability insurance each use different frameworks to convert a WPI into a benefit determination.
Why the Distinction Matters in a Rating Report
A physician's role in a claim ends when the WPI is calculated, documented, and reported. A physician who uses disability language in an impairment rating report, declaring that the patient "cannot work," "is disabled," or "is unable to perform their job duties," has stepped outside their role. These statements are not medical findings. They are legal conclusions that the physician is not qualified to make, and they invite challenge.
More practically: a rating report that crosses into disability language gives opposing counsel an opening to attack the physician's methodology and credibility, even if the WPI itself is technically correct. The report does not have to be wrong to be vulnerable. It just has to give an attorney something to work with.
What the Physician Should and Should Not Include
Include: The specific impairment rating for each affected body region, the diagnostic tests performed and their results, which tables and chapters of the AMA Guides were applied, the combined WPI, any apportionment and its documentation basis, and any functional limitations that are objectively measured.
Do not include: Opinions about whether the patient can return to work, conclusions about employability or vocational capacity, or any statement that characterizes the patient as "disabled" in a legal or administrative sense.
Frequently Asked Questions
Can the same WPI produce different disability ratings in different states?
Yes. A 15% WPI in California produces a different permanent disability rating than the same 15% WPI in Nevada or Texas. Each state applies its own formula and adjustments to the physician's medical finding.
Is it the physician's job to determine if a patient can return to work?
The physician can identify and document functional limitations. But whether those limitations prevent return to a specific job is a vocational and legal question, not a medical one. That determination belongs to vocational experts, state agencies, or the court.
What if the patient asks me to say they are disabled in my report?
Decline. Your report reflects your medical findings. Whether those findings qualify a patient for disability benefits under a specific legal or administrative program is a determination made by that program, not by the rating physician. Stating otherwise exposes you and your report to challenge.
Understanding the impairment/disability distinction is foundational to producing reports that hold up in litigation. CIRS™ certification through AAEME covers this and every other core competency in the AMA Guides.
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