What Do the California WPI Ratings Mean?

by Gilbert Manda ; Updated July 27, 2017
Injury can reduce someone's earning ability.

California follows the American Medical Association (AMA) Guides to evaluate medically determinable impairment. Different scales are used to determine the extent of an employee's injured body parts. The parts are then calculated out of the whole person impairment (WPI) to evaluate the rate of the injury. The rate of the WPI is used to determine the level of compensation for the injured person.

Maximal Medical Improvement

The extent of injury resulting from an industrial accident is determined once it becomes permanent and stationary. Evaluation is made when an injured employee has reached maximal medical improvement (MMI), which is when the condition has become static and can't change significantly with or without medical treatment. California permanent disability rating calculation is initially based on an evaluating a physician's impairment rating, as required by the medical evaluation protocols and rating procedures by the American Medical Association (AMA).

Whole Person Impairment (WPI)

Initial impairment ratings add up and convert to a whole body impairment rating, also known as the impairment standard. To calculate the diminished future earnings capacity, the impairment standard is adjusted. Occupation and age at the time of injury is taken into account to determine the permanent disability rating.

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Measuring a Permanent Disability

The rating of a permanent disability can range from zero to 100 percent. A zero percent injury reflects no reduction of earning capacity, while a 100 percent represents a permanent total disability. Any injury in between is considered partial disability in California, which means an employee still has a certain capacity to earn a wage.

The American Medical Association Guides

The evaluating physician in California uses the AMA Guides to determine the extent of the injury. If you injured your finger, for instance, a finger scale ranges from zero percent to 100 percent. The AMA Guides has a hand, upperexteremity, foot, and lower extremity and whole body scales. The scales are converted to the whole person scale to assess the right impairment rating. A fully impaired upper extremity is equivalent to a WPI in the range of zero to 60 percent. The injured part is converted to a WPI by multiplying by .6.

About the Author

Gilbert Manda has written financial news since 2000. He holds a professional diploma from the London School of Journalism, a Bachelor of Science in global business and public policy from the University of Maryland and a Master of Arts in international journalism from City University London.

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