ProviderPulse

Impairment Ratings and the 6th Edition

From Pinnacol's Medical Director

June 2011
Origin

Care of our ill and injured people has commanded the attention of society from times immemorial. Hammurabi of Ur, who ruled in Babylonia, developed the first legal code in 1750 B.C. Sections 215 to 223 of Hammurabi’s Code dealt with the responsibilities of the physician in the care of the ill and injured.8,9 The physician took significant risk in treating patients. Failure to do so resulted in defined actions (compensation) to equalize the undesired outcome.

Onward from the ancients to the contemporary, the concept of compensation for personal loss gradually refined. Monetary recompense replaced an “eye for an eye and a tooth for a tooth.” The world of workers’ compensation evolved as well, culminating in the development of the American Medical Association Guides to the Evaluation of Permanent Impairment. The Guides or their offshoots now govern the process of impairment assessment.

The American Medical Association (AMA) began publishing articles on guidance for impairment in 1958 with the early focus on the extremities and the back. Over the next 12 years, 12 additional guides appeared in AMA, and, in 1971, a compendium of these 13 guides became the First Edition of The Guides, only 48 pages long.7,10 In 1971, no state required the use of The Guides.10

The AMA published six subsequent editions of The Guides. The 2nd Edition was published in 1984. The majority of the states now use The Guides; here is the breakdown.


In the 6th Edition, the editors note The Guides are “revised periodically to incorporate current scientific clinical knowledge and judgment. For example, the Third Edition, published in 1988, introduced pie charts for range of motion (ROM) impairment evaluation of the upper extremities. In 1993, the Fourth Edition introduced the Diagnosis Related Estimates (DRE) or “injury” model to the evaluation of spinal injuries. A pain chapter was introduced in the Fourth Edition and refined in the Fifth Edition in 2000. The Fifth Edition modified the DRE method and expanded the ROM method for spinal impairment evaluations. The Sixth Edition represents this continued evolution and introduces a “paradigm shift to the assessment of impairment.”7

View a map of the use of The Guides in workers’ compensation.

Colorado and the 3rd Edition (Revised)

The system for determination of impairment in Colorado developed along a dual track. For extremities, the legislature developed a schedule for extremity impairments. Administrative Law Judges determined other impairments based on injury effects on employability. To provide consistent evaluations of impairment, the 1991 Colorado Legislature adopted the AMA Guides to become the Evaluation of Permanent Impairment, Third Edition (Revised), with Senate Bill 91-218.

The Legislature specified the 3rd Edition (Revised) for determination of impairment. At the time, the 3rd Edition (Revised) represented the state of the art in impairment determination.

Since 1991, the 3rd Edition (Revised) has become an icon in the world of Colorado workers’ compensation. The Colorado Division of Workers’ Compensation (DOWC) has worked to keep the text contemporaneous. In 1993, the DOWC wrangled with the definition of impairment of a knee – if it was a knee or an extremity.12 The questions related to the 3rd (Revised) continue and adjustments are necessary as the 20-year-old text forms the basis for 2011 impairment assessment.

Philosophy of impairment ratings: 3rd, 4th, 5th, 6th Editions

As The Guides have matured, the structure has also changed.

The 3rd Edition (Revised) uses the Range of Motion (ROM) model as the basis for assessment of impairment. Pie charts and tables help in determining the numerical assignment of impairment. Particularly, for musculoskeletal concerns, other testing has little impact. Apportionment plays little role for congenital, developmental or age-related conditions.3

The 4th Edition shifted the basis for impairment using the Diagnosis-Related Estimates (DRE) model. The model emphasized the history and physical examination and results of diagnostic testing. The Guides de-emphasized the spinal range of motion and attempted to apportion issues of congenital, developmental and age-related impairments.3

The 5th Edition retained the DRE model (now called DRE method). The text offers discussion concerning use of the ROM model in comparison with the DRE method. The ROM model evaluates apportionment for non-work related conditions, multilevel spinal conditions “(multilevel radiculopathy, multi-level compression fractures and multilevel alteration of motion segment integrity [such as fusions] in the same spinal region), when there is recurrent radiculopathy caused by a new or recurrent disc herniation, and when there are multiple pathologic episodes producing alteration of motion segment integrity and/or radiculopathy (5th Edition, page 380.)”3

The Rules for Evaluation have changed, becoming more defined. These changes relate to confidentiality, combining, consistency, interpolating and rounding, pain, use of assistive devices in evaluation, adjusting for effects of treatment of lack thereof, and for prior impairment ratings.2

All editions note that the scientific evidence is lacking for an evidence-based determination of impairment ratings, leaving only a consensus based approach. The 6th Edition notes:

“Impairment rating: Consensus-derived percentage estimate of loss of activity reflecting severity for a given health condition, and the degree of associated limitations in terms of ADLs. (6th Edition, page 5)

“Historically, the numerical ratings applied for organ system impairment and whole person impairment throughout the Guides are based largely on consensus and expert opinion. Research has focused on reliability and reproducibility of ratings and functional validity of ratings. The evidence basis for impairment percentages assignable to ICF (World Health Organization’s International Classification of Functioning, Disability and Health) functional levels must await further empirical testing; infrastructure exists to develop such studies based on the ICF model, core sets, and ADL assessments.” (6th Edition, page 9)

6th Edition transitions

The 6th Edition approach to impairment is based on the International Classification of Functioning, Disability and Health (ICF). (6th Edition, page iii)

The 6th Edition offers a standardized methodology throughout the chapters of The Guides. This allows for easier performance of the impairment rating since the process is the same. 7 The ICF, designating five classes of impairment severity ranging from none to severe, allows easier gradation of the impairment. The diagnosis based grid with ICD-9 diagnoses derives from consensus-based dominant criterion. 7 The Guides emphasize functionally-based histories, physical findings and objective test results to determine the grade within the impairment class.7

The 6th Edition has attempted to:


Basis of impairment ratings

All editions of The Guides have similar definitions but with different emphasis based on function.


The Guides emphasizes objective assessment, necessitating a medical evaluation. Impairment may lead to functional limitations or the inability to perform ADLs and reflects a change from normal or pre-existing status. Although The Guides use objective and scientifically based data when available, the impairment rating often remains based on the clinical experience and consensus of the contributors as it has been in the preceding editions. This is particularly the case for the musculoskeletal system, the area of primary usage for the Guides.2

The goal of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) is “to provide a standardized, objective approach to evaluating medical impairment” (6th ed, p 20).5

Results of impairment ratings: systems variation

Only Colorado mandates use of the AMA Guides 3rd Edition (Revised). All other states use more current editions of The Guides. The subsequent editions of The Guides result in lower ratings and require greater time and effort from physicians.1

Dr. Chris Brigham, an editor of The Guides since the 3rd Edition (Revised) worked with the DOWC to compare impairments for the 3rd, 4th and 5th Editions of The Guides. Dr. Brigham and the DOWC evaluated 40 upper extremity, 60 lower extremity and 150 whole person cases.1

The findings showed:

Edition CO Upper Extremity Reassessed Upper Extremity CO Lower Extremity Reassessed Lower Extremity Spine Spine Reassessment
3rd 14.5%

11.76%

18.35%

18.15%

 17.6%

17.1%
4th  

11.15%

 

13.97%

  

8.61%
5th  

11.28 %

 

13.97%

  

10.72%
     

Knee  18.1%

Knee
12.9%

    

The 6th Edition did not exist at the time of the chart evaluation by Dr. Brigham and the DOWC. The findings reflect lower ratings for the 4th and 5th Editions from the 3rd Edition (Revised). As noted below, the 6th Edition ratings more closely mirror the findings of the 4th Edition.

In further evaluation of the 4th, 5th and 6th Editions, Dr. Brigham found no statistically significant difference between the 4th and 6th Editions. The 5th rated slightly higher with statistical significance. For impairments of 10% or greater Whole Person Impairment (WPI) based on the 5th Edition, the averages were:


The increase found in the 5th Edition did not have an accompanying scientific rationale.

Spinal conditions account for significant impairment assessments. The 6th Edition changed the basis for impairment determination. The consensus of the editors was that surgery should improve rather than worsen function and, thus, the surgery itself is not impairable. They reached similar conclusions for carpal tunnel release and joint replacement.4

Examiner variation

In Colorado, to perform an impairment rating, the physician must be Level II Accredited by the DOWC. The course derives from the 3rd Edition (Revised). The course covers the various organ systems and the process for performance of impairment ratings.

Colorado is the only state in which the DOWC requires training under the auspices of the DOWC.

Utilization of The Guides should produce good interrater coherence. Such is not the case. In evaluating impairment ratings in 2005 and 2010, Dr. Brigham found a consistent 80% disagreement between raters.5 He found significant differences in the assessed impairments. His study compared the physicians of California, Nevada and Hawaii. In California, the difference was 12% whole person (WP), Nevada 3% WP and Hawaii 2% WP.5

The difference becomes stark depending on the source of the referral. For patient-referred evaluations, the difference in rating was 22% WP, while for defense-referred evaluations the difference was 6.6% WP.5

Appropriate causation assessment continues to haunt impairment ratings. The Level II Curriculum offers better criteria for determination of causation than do The Guides. The determination of causation is historically an adjudicatory process. Medical probability still rests with physicians.

To attribute medical probability, confounding issues may cloud the determination. These include:


The physician performing the impairment rating must be aware of inherent problems in the determination of the rating, which include:


Conclusion

Different states use different editions of The Guides or have their own impairment rating systems.

The Guides vary in their mechanisms or impairment assessment from range of motion to diagnosis-related estimates with shifting to evidence based medicine and use of international standards.

The impairment ratings for the same condition differ depending on the edition of The Guides. The 4th, 5th and 6th Editions determine impairments to be less than the 3rd Edition (Revised). Later editions of The Guides allow for greater interrater agreement.

The DOWC and the Level II accreditation program have provided greater consistency in ratings.
The outcome of the rating is still most dependent on the physician providing the rating. Dispassionate rationality with evidence based medicine, attention to causation and adherence to the process continue to offer the best impairment ratings.

Ratings are not divine declarations. They are based on good medicine and the consensus of experts. What comes out is only as good as what goes in.

1 Comparative Analysis of Third Edition, Revised; Fourth; and Fifth Edition—Ratings: The State of Colorado Study Jan/Feb 2004, 1-3, 9-11
2 Comparative Analysis of Third Edition, Revised; Fourth; and Fifth Edition—Ratings: The State of Colorado Study Mar/Apr 2004, 1-3, 6-15
3 Comparative Analysis of Third Edition, Revised; Fourth; and Fifth Edition—Ratings: The State of Colorado Study May/June 2004, 1-3, 6-11
4 Comparative Analysis of AMA Guides Ratings by the Fourth, Fifth, and Sixth Editions* Jan/Feb 2010, pp 1-7
5 Impairment Ratings: Observations Based on Review of More Than 6,000 Cases Mar/Apr 2010, pp 1-10
6 Causes of Erroneous Fifth Edition Ratings Mar/Apr 2010, pp 11-13
7 Guides to the Evaluation of Permanent Impairment, Rondinelli, et al. 6th Edition, 2007, pp 1-30
8 http://www.innovateus.net/content/medicine-code-hammurabi
9 http://public.wsu.edu/~dee/MESO/CODE.HTM
10 http://bnainfo.bna.com/bnabooks/ababna/annual/99/annual31.pdf
11 http://www.impairment.com/Useof_AMAGuides.htm
12 http://www.colorado.gov/cs/Satellite?blobcol=urldata&blobheader=application%2Fpdf&blobkey=id&blobtable=MungoBlobs&blobwhere=1251616386058&ssbinary=true