We conclude this chapter on the California disability rating system with a discussion of the AMA Guides. While empirical evidence is
limited, many system participants believe the AMA Guides would improve consistency. In the last subsection, we examined the inconsistency of ratings, and noted that it can lead to ratings that are invalid. It is important to note that validity in California is measured relative to disability. The AMA Guides are not designed to measure disability-- rather, they are intended to measure impairment. Unfortunately, the validity of the Guides at measuring impairment cannot be tested, since there is no independent empirical measure of impairment like the
measures of wage loss that we used to test the validity of California ratings.
To understand the utility and limitations of the AMA Guides, it is helpful to examine their description of the steps to evaluate
impairment.10 The Guides describe three steps for evaluating
impairment. The first step is designed to accurately document the clinical status of an injured person by obtaining a medical history, conducting a medical evaluation including appropriate tests, and
completing diagnostic procedures. Second, once the clinical status of a patient is documented, a physician then determines “the nature and
extent of impairment or dysfunction of the affected body part or system.” This step requires that the physician analyze the medical history, as well as clinical and laboratory findings for the injured person. The Guides then describe a third step which requires physicians to compare “results of analyses with criteria specifying guides for the particular part, system, or function.” However, this third step really involves two separate determinations or steps of its own.
To carry out the third step described by the Guides, a physician must first determine the degree of impairment of the particular organ or system and then, using this finding, determine the “whole person
impairment” which is rated on the AMA Guides’ 100 point scale. The first two steps of the evaluation and the first part of the third step, the evaluation of an organ system impairment, are well within the normal experience and knowledge of a physician. For example, a physician may carry out the first two steps and reach a conclusion that an injured worker has a 30 percent limitation in motion for an injured wrist. The second part of the third step, the evaluation of a whole person
impairment, is not an ordinary medical judgment. Indeed, it is not clear that a whole person impairment scale is meaningful. The AMA
Guides provide no definition or justification for this scale, describing only the high end of the scale. A score of 0 presumably implies that there is no impairment because of an injury. The Guides define the other end of the scale as: “95 percent to 100 percent is considered to represent almost total impairment--a state that is approaching death.” Unfortunately, a scale that has nothing wrong at one end and death at ___________
the other is not very useful nor does it give any information about what the AMA believes to be a 50 percent impairment as opposed to a 25
percent impairment.
For example, as described on pages 154-164 of the AMA Guides, Fourth Edition, the example assumes a relevant history of an insulator who worked with asbestos-containing products for 30 years. The medical evaluation presumably showed moderate dyspnea (shortness of breath), the presence of pulmonary rales (a distinctive sound made during
respiration), with x-ray confirmation of pulmonary opacities or scarring that is typical of asbestosis. As part of this examination, the AMA Guides instruct the physician to conduct spirometry, a test that measures pulmonary function. As the second step in the impairment
evaluation, the AMA Guides require the physician to determine the injury (here a restrictive pulmonary impairment) and analyze the laboratory findings, which, for example, show that the results of a pulmonary function test produced a forced vital capacity equal to 2.0.
The AMA Guides then require, as a third step, that the physician determine the extent of respiratory impairment by comparing the results of the examination and tests to criteria established in the Guides. The Guides show that this worker would have, by example, a respiratory
impairment of 45 percent--his pulmonary level is 55 percent of normal for a person of that age and height. Note that this impairment deals only with pulmonary impairment, not with the whole person impairment that is the objective of the AMA Guides. The Guides, however, translate the specific respiratory impairment into a whole person impairment
somewhere between the range of 26 to 50 percent.
Note that all of the steps of this medical evaluation are conducted routinely by doctors up to and through the determination of degree of respiratory impairment. The fourth step, the whole person impairment, is not a matter of routine medical practice, but must be made in order to place this injured worker on a scale that can be compared to workers who suffered all other manner of injuries, such as ruptured cervical discs, amputations of fingers, or loss of sexual function.
The AMA Guides attempt to put all residual conditions resulting from injuries onto a one dimensional scale, assuming that the limitation
on a person’s activities from one type of organ system impairment can be compared to that of all other types of organ system impairments. It is not obvious that these different limitations can all be compared and ranked with each other, and there is no way to test it. Furthermore, the AMA Guides not only attempt to rank these disparate types of organ system impairments on one scale, but the use of this scale to determine dollar benefits implies that these rankings have some relational
meaning. For example, the use of the AMA Guides to determine disability payments implies that the difference between an injury with an AMA
rating of 40 compared to an injury with an AMA rating of 50 is the same as the difference between an injury with a rating of 30 to one with a rating of 40. It is impossible to verify whether this is true.
While the ability of the AMA Guides to measure impairment is unknowable, it remains possible that the Guides would provide a better measure of disability than the current California system. In other words, it is possible that the AMA Guides rank individuals by wage loss more effectively than the California disability rating system. We will consider this possibility and other ways to improve the disability rating process in Section 8.
7. PROCESSING PPD CLAIMS
The analyses of the last two chapters have shown how wage losses, workers’ compensation benefits and the adequacy of benefits as
replacement for wage losses differ between major and minor disability claims. This section presents a system level analysis of this key distinction in claims. Our analysis shows that, overwhelmingly, California’s workers’ compensation system for PPD claims is one for handling minor disability claims--the very claims that appear to be treated most poorly by that system.