Apportionment for physicians: Labor Code §4663 and §4664

Apportionment is based on causation

“Apportionment of permanent disability shall be based on causation” (Lab. Code §4663(a)). A physician reporting on permanent disability must address the causation of that disability (§4663(b)) — a different question from whether the injury itself was industrial.

What a complete report contains

A report is not complete on permanent disability without an apportionment determination: the approximate percentage of the permanent disability caused by the industrial injury, and the approximate percentage caused by other factors before and after it, including prior industrial injuries (§4663(c)).

If you cannot make the determination, state the specific reasons why you could not determine the effect of the prior condition; then consult other physicians or refer the employee to a physician from whom the employee may seek treatment or evaluation, to make the final determination (§4663(c)).

The employee must, on request, disclose all previous permanent disabilities or physical impairments (§4663(d)). These rules do not apply to the presumptive injuries listed in §4663(e).

Prior awards and the lifetime limit — §4664

The employer is liable only for the percentage of permanent disability directly caused by the industrial injury (§4664(a)).

If the employee has received a prior award of permanent disability, it is conclusively presumed that the prior disability exists at the time of any later industrial injury (§4664(b)).

Awards for any one region of the body may not exceed 100 percent over the employee’s lifetime, unless the injury is conclusively presumed total under §4662. The regions are hearing; vision; mental and behavioral disorders; the spine; the upper extremities including the shoulders; the lower extremities including the hip joints; and the head, face, cardiovascular, respiratory and all other systems (§4664(c)(1)).

How ChironAI™ OM helps

Chiron analyses industrial and non-industrial causation-of-disability factors across the record and prepares a working draft of the apportionment narrative; the physician decides the conclusion. Staff flag a worker’s self-reported prior claims as unconfirmed candidates for the prior-award record, which the physician confirms or marks not applicable, and Defend This tests the adopted apportionment as opposing counsel would.