Impairment and disability evaluation (AMA Guides framework)
What this domain tests
This domain tests whether you can distinguish impairment from disability and apply the AMA Guides method specified by the governing jurisdiction. The exam focuses on correct edition, maximal medical improvement, objective findings, combining rules, and apportionment.
Core rules and concepts
- Impairment is a loss of body function or structure measured by a standardized method. Disability is the effect of impairment on activities, work, and life roles and depends on context. The AMA Guides rate impairment, not employability or legal disability.
- Editions differ. The 3rd, 4th, 5th, and 6th editions use different diagnosis-based, range-of-motion, and DRE methods. Never mix editions or tables. Colorado workers compensation has historically specified the AMA Guides 3rd edition, revised, for many impairment ratings; verify the current statute and Division rule before applying any edition.
- Maximal medical improvement means the condition is stable and further treatment is not expected to materially improve function. It is not the same as being cured or pain-free.
- The rating process: confirm diagnosis, establish MMI, use objective findings and validated measurements, apply the correct table or diagnosis-based category, combine values using the Guides rules rather than simple addition, address pain-related impairment only as permitted, and apportion when the jurisdiction allows.
- Whole-person impairment is not a disability percentage and should not be translated into a work restriction without a separate functional analysis.
Worked example
A worker has a lumbar fusion at L4-L5 and residual radiculopathy. Under a diagnosis-based edition, the examiner identifies the correct fusion category, checks whether the specified approach and levels match, adds any permitted residual symptom adjustment, and combines with the nerve-root impairment using the Guides method. Under a range-of-motion edition, the examiner would instead use valid lumbar motion measurements and the relevant DRE category. The examiner must not assign a round percentage based on experience or add the fusion and radiculopathy percentages arithmetically.
Traps that cost marks
Using the newest edition when the jurisdiction specifies an older one; mixing editions; rating before MMI; adding percentages instead of combining per the Guides; double-counting the same finding; using invalid range-of-motion efforts; and calling an impairment rating a disability rating.