Askew v. Industrial Claim Appeal Office, 927 P.2d 1333 (Colo. 1996) explicitly recognizes that “impairment” and “disability” are distinct concepts. Impairment pertains to a person’s health status and is assessed by medical means. Disability pertains to a person’s capacity to meet personal, social, or occupational demands, and is assessed by non-medical means. Thus, an impairment may exist without causing any disability. Askew, 927 P.2d at 1337; Baldwin Construction, Inc. v. Industrial Claim Appeals Office, 937 P.2d 895 (Colo.App. 1997). Askew necessarily contemplates that where occupational and non-occupational factors contribute to a particular component of the claimant’s overall impairment, the claimant is entitled to benefits based on the entire impairment rating unless the pre-existing impairment was independently disabling at the time of the subsequent injury.
It is true, as the respondents argued, that under Askew a claimant may receive compensation based on impairment which is, to some degree, not causally related to an industrial injury. However, the formula established by Askew recognizes that some pre-existing impairments, which are not causally related to the industrial injury, have no impact whatsoever on the claimant’s earning capacity and do not produce any “disability” unless aggravated or exacerbated by a subsequent industrial injury. Similarly, a pre-existing impairment which was once disabling may improve to the point that it is no longer disabling. Such pre-existing impairments may again become disabling when aggravated by a subsequent industrial injury. Thus, the Askew formula does no more than recognize the traditional workers’ compensation principle that when an industrial injury precipitates disability from a latent pre-existing condition, the entire disability is compensable. Askew v. Industrial Claim Appeals Office, 927 P.2d at 1338; Subsequent Injury Fund v. Thompson 793 P.2d 576 (Colo. 1990).
According to the Impairment Rating Tips, directed to Level II Accredited physicians, “to apportion prior injuries that are non-work related, they must have been identified, treated, and independently disabling at the time of the current work-related injury. If the prior non-work-related injury was not independently disabling at the time of the current injury, you may not apportion.” (emphasis added).