The American Medical Association Guides to the Evaluation of Permanent Impairment provide standardized methods for rating lasting physical and mental impairments. These ratings translate medical findings into percentage values used in disability claims, workers compensation, and personal injury litigation. Understanding how AMA impairment ratings work helps claimants and attorneys interpret evaluations and ensure proper assessment of permanent disabilities.
Purpose of Impairment Ratings
Impairment ratings provide objective, standardized measures of permanent physical or mental deficit. Rather than relying solely on subjective complaints, ratings use defined criteria to convert medical findings into numerical values. This standardization allows comparison across different injuries and evaluators.
The AMA Guides are used differently across various contexts. Workers compensation systems in many states mandate AMA Guides ratings for disability determinations. Personal injury litigation may use ratings as evidence of disability severity though courts are not bound to accept them as definitive.
Impairment differs from disability. Impairment measures physical or mental deficit while disability reflects how impairment affects specific activities like work. A person with significant impairment might have minimal disability in their particular occupation, while modest impairment might be highly disabling in other contexts.
How Ratings Are Determined
Qualified physicians perform impairment evaluations following AMA Guides protocols. Evaluators examine patients, review records, and apply Guides criteria to reach ratings. The Guides provide specific protocols for different body systems and conditions.
Ratings for musculoskeletal conditions use range of motion measurements, diagnostic imaging findings, and surgical outcomes. Specific criteria define rating ranges for common conditions like disc herniations, fractures, and joint injuries. Loss of range of motion, strength deficits, and need for surgical intervention all affect ratings.
Neurological impairment ratings address brain injuries, peripheral nerve damage, and spinal cord injuries. Cognitive testing, motor and sensory deficits, and functional limitations all contribute to neurological ratings. The Guides provide separate chapters for central and peripheral nervous system impairments.
Psychological impairment ratings address mental health conditions including depression, anxiety, and PTSD. These ratings evaluate how mental conditions affect daily functioning across various domains. Psychiatric evaluation and psychological testing inform these assessments.
The Combined Values Chart
Multiple impairments from a single incident are combined using the Combined Values Chart rather than simply added. The chart accounts for the fact that additional impairments to an already-impaired person cause proportionally less additional loss. A person with 50% impairment who suffers additional 30% impairment does not have 80% total impairment under the combining formula.
Apportionment may reduce ratings when pre-existing conditions contributed to the impairment. If a person had existing impairment before the accident, only the additional impairment caused by the accident should be attributed to the claim. Apportionment is often contested between plaintiffs and defendants.
Using Ratings in Litigation
Impairment ratings provide evidence of disability severity but are not determinative of damages. Juries consider ratings along with other evidence of how impairments affect the specific plaintiff. A 10% impairment might be devastating for one person's career while causing minimal impact for another.
Defense and plaintiff experts may reach different ratings from the same findings. The Guides provide ranges and judgment calls that different evaluators may resolve differently. Understanding why experts disagree helps attorneys prepare cross-examination and rebuttal.
Higher ratings generally support larger damage awards, but the relationship is not linear. Ratings help establish permanence and severity as foundations for other damage calculations. Lost earning capacity, life care planning, and pain and suffering all build on established impairment.
Challenging Ratings
Low ratings can be challenged by showing evaluators misapplied Guides criteria or overlooked relevant findings. The Guides are technical documents that evaluators sometimes misinterpret. Attorneys familiar with the Guides can identify errors in adverse ratings.
High ratings from defense evaluators may understate impairment by excluding certain conditions or applying criteria incorrectly. Plaintiff experts should review defense evaluations for errors and provide rebuttal opinions when appropriate.
Updating ratings may be appropriate if conditions worsen after initial evaluation. The Guides permit reevaluation when conditions change. Deterioration after initial rating can support updated assessments.
AMA Guides Versions
The AMA Guides have gone through multiple editions, with the current being the Sixth Edition. Different states and systems may require different editions. Ratings can differ significantly between editions for the same conditions, making edition selection important.
Some find the Sixth Edition controversial because it changed methodology from earlier editions. Several states continue using earlier editions. Understanding which edition applies and how it differs from alternatives helps interpret ratings properly.
Conclusion
AMA impairment ratings provide standardized measures of permanent disability used throughout the legal and insurance systems. Understanding how ratings are determined, combined, and applied helps claimants ensure fair evaluation and attorneys effectively present impairment evidence. While ratings do not determine damages, they provide important evidence supporting permanent disability claims.