DEPARTMENT OF LABOR AND EMPLOYMENT
Division of Workers’ Compensation
7 ccr 1101-3
WORKERS’ COMPENSATION RULES OF PROCEDURE
Rule  12	Permanent Impairment Rating Guidelines

12-3	APPORTIONMENT

(A)	For claims with a date of injury prior to July 1, 2008, a Level II accredited physician (“the Physician”) shall apportion any pre-existing medical impairment, whether work-related or non-work-related , from a work-related injury or occupational disease using the AMA Guides, 3rd Edition, Revised, where medical records or other objective evidence substantiate a pre-existing impairment to the same body part.  Any such apportionment shall be made by subtracting from the injured worker’s impairment the pre-existing impairment as it existed at the time of the subsequent injury or occupational disease.  The Physician shall explain in their written report the basis of any apportionment.  If there is insufficient information to measure the change accurately, the Physician shall not apportion.

(B)	For claims with a date of injury on or after July 1, 2008, the Physician may provide an opinion on apportionment for any pre-existing work-related or non-work-related  permanent impairment to the same body part using the AMA Guides, 3rd Edition, Revised, where medical records or other objective evidence substantiate a pre-existing impairment. Any such apportionment shall be made by subtracting from the injured workers impairment the pre-existing impairment as it existed at the time of the subsequent injury or occupational disease.  The Physician shall explain in their written report the basis of any apportionment. If there is insufficient information to measure the change accurately, the Physician shall not apportion.  The Physician may be asked to provide an opinion as to whether the previous medical impairment was identified, treated and independently disabling at the time of the work-related injury that is being rated. 

(1)	The effect of the Physician’s apportionment determination is limited to the provisions in §8-42-104.  When filing an admission an insurer may apportion only if documentation is provided reflecting compliance with §8-42-104.         

(2)	The Physician may provide an opinion on the apportionment of medical and temporary disability benefits.  The claimant’s receipt of medical and temporary disability benefits may not be reduced based on any such opinion.