Impairment rating basics: the AMA Guides, 5th Edition, in California

From impairment to disability

California rates permanent disability by taking account of the nature of the injury, the employee’s occupation and age at injury (Lab. Code §4660.1(a)). The “nature of the physical injury” incorporates the descriptions, measurements and impairment percentages of the AMA Guides to the Evaluation of Permanent Impairment, 5th Edition, with the whole person impairment multiplied by an adjustment factor of 1.4 (§4660.1(b)).

The rating schedule and the schedule of age and occupational modifiers are prima facie evidence of the percentage of permanent disability (§4660.1(d)).

What the physician supplies

The physician’s job is the impairment: the Guides chapter, table and category for each body part, the measurements that place it there, and the whole person impairment. The rating that follows applies the schedule and modifiers to that impairment.

For a treating physician, the permanent-and-stationary report describes impairment in accordance with the 5th Edition Guides (8 CCR §9785(i); see the PR-2/PR-4 guide).

Departing from a strict rating

Section 4660.1(h) states that the Legislature did not intend to overrule Milpitas Unified School District v. WCAB (Guzman) (2010) 187 Cal.App.4th 808. Where a physician departs from a strict Guides category, the report should document why the strict rating does not reflect the impairment and why the chosen alternative does — that reasoning is what a reviewer will look for. Read the decision itself before relying on it.

Statutory limits

For a compensable physical injury, impairment ratings for sleep dysfunction, sexual dysfunction or psychiatric disorder arising out of it do not increase the rating, except where the psychiatric injury resulted from being the victim of, or directly exposed to, a violent act, or from a catastrophic injury (§4660.1(c)). The section does not limit treatment for those conditions, and does not preclude a finding of permanent total disability under §4662 (§4660.1(c)(1), (g)).

How ChironAI™ OM helps

Chiron proposes the AMA Guides 5th-edition chapter, table and category per body part from the diagnoses and exam findings, and checks whether a rating that departs from a strict Guides category carries the documented justification Almaraz/Guzman requires. The physician decides the impairment and signs.