The Sixth Edition of the AMA Guides to the Evaluation of Permanent Impairment, published in 2007, is the new international standard serving as the first step in medically assessing disability. The Sixth Edition introduced a paradigm shift in assessing impairment. An innovative methodology is used to enhance the relevancy of impairment ratings, improve internal consistency, promote greater precision, and simplify the rating process. The approach is based on a modification of the conceptual framework of the International Classification of Functioning, Disability, and Health (ICF). Standardized methodology is applied to each chapter to enhance the relevancy of impairment ratings, improve internal consistency, and promote ease of application to the rating process.

An analytical framework based on the ICF generates five impairment classes that permit the rating of the patient from no impairment to most severe. A diagnosis-based grid has been developed for each organ system that arranges commonly used ICD-9 diagnoses within the five classes according to the consensus-based dominant criterion. Functionally based histories, physical findings and broadly accepted objective clinical test results are integrated where applicable to help physicians determine the grade within the impairment class.

Dr. Christopher Brigham is the senior contributing editor for the Sixth Edition of the AMA Guides. He has personally conducted a wealth of scientific research on the use, misuse, and abuse of impairment rating systems. His research findings have clearly demonstrated that physicians typically misuse or even ignore the Guides, thereby causing the overwhelming majority of impairment ratings to be inaccurate. Typically, an impairment rating provided by a local physician in an individual case will be two to three times higher than the Guides would have called for. Dr. Brigham's detailed analysis of this phenomenon has helped to identify key issues regarding what is going wrong with such erroneous ratings, and has resulted in the development of new best practice strategies. Such strategies call for strict adherence to the most current professional standards, both in regard to obtaining ratings that are accurate and unbiased and in regard to recognizing and managing erroneous ratings.