Impairment Ratings: National Study Reveals High Error Rate

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The AMA Guides to the Evaluation of Permanent Impairment, Fifth Edition are the accepted standard for defining impairment, the quantification of the impact of an injury or illness. The resulting rating is widely used in workers' compensation, automobile casualty, Longshore and Harbor Workers Act, and personal injury cases to define the impact of an injury or illness. A recent study confirms the finding that most impairment ratings are incorrect and therefore should be critically reviewed by experts to determine if the rating is accurate.

The AMA Guides to the Evaluation of Permanent Impairment, Fifth Edition are the accepted standard for defining impairment, the quantification of the impact of an injury or illness. The resulting rating is widely used in workers' compensation, automobile casualty, Longshore and Harbor Workers Act, and personal injury cases to define the impact of an injury or illness. A recent study confirms the finding that most impairment ratings are incorrect and therefore should be critically reviewed by experts to determine if the rating is accurate.

Brigham and Associates, Inc. (http://www.impairment.com) implemented a new web-based impairment evaluation database system with extensive tracking facilities in July 2006. Impairment ratings performed by other physicians are analyzed by a team of highly trained professional and clinical staff who are very experienced in the use of the AMA Guides. Resulting analysis reports are used by clients for case management, as feedback to the original rating physician, as evidence, in negotiation, or to assist in preparing an effective cross-examination.

Of 874 national impairment critiques performed between July 2006 and February 2007, 751 (86%) were incorrect, with the average original rating 18.5% whole person permanent impairment (WPI) and the average revised (corrected) rating 5.2% WPI. The high error rate cannot be attributed solely to selection bias, i.e. a client referring cases suspected of being incorrect. Clients have recognized the value of having every rating screened by Brigham and Associates, Inc. and having detailed critique reports prepared on ratings that were significantly incorrect. Review of 73 consecutive California cases revealed an error rate of 82% among the ratings performed, with the average original rating of 12.3% WPI and the revised (corrected) rating of 3.7% WPI. Review of 35 consecutive Hawaii cases revealed a lower error rate at 38%.

The financial significance of these errors is dependent on jurisdiction. In California workers' compensation cases the whole person permanent impairment is used as the initial basis to define permanent disability (PD); with conservative assumptions the observed error rate would result in a difference exceeding $850,000 per 100 cases. In Hawaii the observed findings results in an excessive cost due to incorrect ratings exceeding $200,000 per 100 cases.

Among all of the cases the most common diagnosis was sprain lumbar region representing 23% of all ratings, with the average original rating being 10.3% WPI and the average corrected rating being 0.9% WPI; the vast majority of these cases were rated on the basis of pain complaints or erroneous use of the Range of Motion Method, and upon careful review rarely had ratable impairment according to the Diagnosis Related Estimates Method. The finding of minimal impairment with most low back injuries is also consistent with recent studies that demonstrate that minor trauma does not appear to increase the risk of serious low back pain episodes or disability. The vast majority of incident-averse LBP events may be predicted not by structural findings or minor trauma but by a small set of demographic and behavioral variables. (Reference: Carragee E, et al. Does Minor Trauma Cause Serious Low Back Injury. Spine 13(25):2942-2949, 2006)

Ten percent of the cases were carpal tunnel syndrome with an average original rating of 10.5% WPI and average (revised) corrected of 3.2% WPI; the most common problems were inappropriately rating on grip strength and rating on subjective complaints rather than objective findings. Most impairment evaluations of carpal tunnel syndrome inadequately assessed causation; more recent studies have concluded that the vast majority of carpal tunnel cases are not occupationally related. Shoulder injuries averaged 8.8% WPI and upon correction were found to be 3.7% WPI; the most common error was failure to consider the opposite extremity as normal for the individual. Internal derangement of the knee averaged 7.9% WPI and upon correction 3.3% WPI. Overall, considering all cases with objective findings of impairment, a typical impairment value is approximately 6% whole person permanent impairment.

It is Dr. Brigham's impression that the financial costs of incorrect ratings may be exceeded by the human costs. It is difficult to define the impact to a specific patient when a physician falsely portrays that individual as being significantly impaired or disabled. Such messaging may result in dysfunctional behavior and other negative lifelong consequences.

The assessment of impairment evaluations requires a unique skill set and must be performed by evaluators with knowledge, skills and abilities in both clinical medicine and the use of the AMA Guides to the Evaluation of Permanent Impairment. It is very cost-effective to have every impairment rating reviewed by an AMA Guides expert to determine if the rating is accurate and to utilize the clinical data provided to reassess the impairment. Evaluation and feedback is essential to quality improvement and review of every rating reflects best practice.

About Brigham and Associates:

Brigham and Associates, Inc. (http://www.impairment.com) was founded in 1995, and is recognized as the nation's leading resource on impairment, disability and causation evaluation. Their well-trained and highly credentialed professional staff utilize advanced Web-based technology and database systems to provide high quality, cost-effective consultation services, including impairment report critiques and case reviews. They are unique in providing an online process for case referral, impairment rating screening, and in-depth analysis. The firm also provides evaluation resources, publications and training in live, web-based and online education formats (http://www.guidesiq.com). Brigham and Associates, Inc. provides as a complimentary service weekly emailed tips on impairment evaluation (http://www.impairment.com/tips).

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Mindy Brigham