This is the first of a series of articles providing insight to the new Sixth Edition of the AMA Guides to the Evaluation of Permanent Impairment. In this issue we provide information on the use of the Guides. The Guides serves as the standard for defining impairment in most workers' compensation, motor vehicle casualty and personal injury cases. The Sixth Edition, published in December 2007, introduced new approaches to rating impairment, using innovative methodology 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), although the fundamental principles underlying the Guides remain unchanged. Although there has been considerable praise for the new Edition, there has also been controversy over the needed change. The approach to assessing impairment is different and some of the values of impairment associated with specific diagnoses have changed. To appreciate the significant impact of the Sixth Edition, it is useful to understand the history and structure of the Guides.

The AMA Guides to the Evaluation of Permanent Impairment is the basis for defining impairment in the vast majority of workers' compensation jurisdictions, and the use of the most recent Edition will be required immediately by certain state jurisdictions and for Federal and Longshore and Harbor Workers Act cases.

The Guides started in 1958 with publication by the American Medical Association (AMA) of the article, "A Guide to the Evaluation of Permanent Impairment of the Extremities and Back." This was followed by additional guides published in the Journal of the American Medical Association. In 1971 a compendium of 13 guides became the First Edition. The Second Edition was published thirteen years later in 1984, with publication of the Third Edition in 1988. The Third Edition was the first to use the Swanson methodology which assigned discreet impairment ratings to specific range of motion (ROM) deficits of the upper extremities. Although the Third Edition was replaced two years later by the Third Edition, Revised, which is still used by the State of Colorado for workers compensation cases, the use of ROM "pie charts" to assess impairment from upper extremity ROM deficits was retained.

The Fourth Edition, published in 1993, provided many refinements, including the Diagnosis- Related Estimates (DRE) or "injury" model for the evaluation of spinal injuries, alternative approaches to assessing lower extremity impairment, and a pain chapter. The DRE model was unique in allowing for assignment of an impairment rating based solely on the diagnosis, even if MMI had not yet been reached. The Fourth Edition is still used for assessing workers compensation cases in Alabama, Arkansas, Connecticut, Kansas, Maine, Maryland, Mississippi, South Dakota, Texas, and West Virginia.

The Fifth Edition, published in 2000, was nearly twice the size of its predecessor, provided more detailed directives in all chapters, and modified the approaches used for spinal impairment evaluation by providing guidance on choice of the rating method and providing ranges for Diagnosis-Related Estimates (DRE) categories. Prior to the availability of the Sixth Edition twenty six states made use of the Fifth Edition, including Alaska, Arizona, California, Delaware, Georgia, Hawaii, Idaho, Indiana, Iowa, Kentucky, Louisiana, Massachusetts, Montana, Nevada, New Hampshire, New Mexico, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Utah, Vermont, Washington and Wyoming.

The Sixth Edition represents this continued evolution in impairment evaluation. Many states require the use of the "most recent Edition" of the Guides either by statute or code; therefore, states that would be expected to implement the Sixth Edition immediately include Alaska, Hawaii, Kentucky, Louisiana, Mississippi, Montana, New Hampshire, New Mexico, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Vermont and Wyoming. Kentucky, Tennessee and Vermont are delaying introduction of the Sixth Edition until the impact of the changes are better understood. The most recent edition is also expected to remain the standard for automobile casualty and personal injury cases, both domestically and internationally. Some of the countries abroad that use the Guides include Australia, Canada, Hong Kong, Korea, New Zealand, and South Africa.

The Sixth Edition is the new standard for all other cases. Federal workers' compensation laws cover all federal employees (including postal workers) and citizens of Washington, DC. Federal systems include Federal Employees' Compensation Act (FECA), Energy Employees Occupational Illness Compensation Program Act, and Longshore and Harbor Workers' Compensation Act (LHWCA). Under the Federal Employees' Compensation Act (FECA 5 USC 8107) benefit is given for permanent impairment to specific body parts including extremities, hearing, vision, and loss of specific organs. Under the Longshore and Harbor Workers' Compensation Act ratings are performed for "scheduled injuries" (e.g., a scheduled member of the body defined by section 8(c)(1)-(20) of the LHWCA). This includes upper extremity injuries (with the exception of the shoulder), lower extremity injuries, and hearing loss.