AMA Guides® Newsletter

Articles

Apportionment Analysis

Christopher R. Brigham, Henry J. Roth

Pages 1–11

DOI: 10.1001/amaguidesnewsletters.2004.JulAug01

Abstract
In the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, apportionment refers to the “distribution or allocation of causation among multiple factors that caused or significantly contributed to the injury or disease and existing impairment,” and causation is the process of determining “an identifiable factor (eg, accident or exposure to hazards) that results in a medically identifiable condition.” Causality assessment requires a clear understanding and discussion of causal relationships; apportionment analysis refers to the extent to which factors may have contributed to a particular effect or impairment. A causal relationship requires three elements—a cause, an effect, and a specific relationship between them—the absence of any one of which disqualifies causality. Apportionment is an estimate of the degree to which each of various medically probable occupational or nonoccupational factors contributed to a particular impairment. The unique legal standards of compensability and apportionment vary by locality, and the apportionment of disability involves assessing the functional effects of different injuries over time. Evaluators should consider the effect of using the Combined Values Chart on the final assessment and must carefully distinguish factors that are combined vs those that are added or subtracted. A sidebar discusses important changes to the State of California's Workers’ Compensation.
Case Study: Shoulder Injury

Pages 4–12

DOI: 10.1001/amaguidesnewsletters.2004.JulAug02

Abstract
This issue of The Guides Newsletter introduces a new feature, Case Study, that illustrates some of the challenges encountered in rating shoulder impairment. The history presents the case of a 50-year-old, right-hand dominant white male evaluated for impairment due to left shoulder pain, stiffness, and weakness. His initial injury occurred at work in December 2001 when he used his left arm to prevent himself from falling. After five months of nonoperative treatment, including one subacromial steroid injection, physical therapy, and a second opinion, he underwent open subacromial decompression and acromioplasty and open distal clavicle excision. He returned to work and pain resolved after a year but recurred in September 2003. The patient was examined 19 months after the surgery, and the examining physician evaluated the patient's clinical status at that time, reviewed diagnostic studies performed, diagnosed maximum medical improvement, and, using the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), assessed 11% whole person impairment. Readers are encouraged to use the materials presented to this point to prepare their own rating that they can compare with an analysis (published elsewhere in this issue) that reviews the examining physician's report and finds that it was inconsistent with the AMA Guides and was erroneous in certain key points.
Question and Answer

Pages 5–9

DOI: 10.1001/amaguidesnewsletters.2004.JulAug03

Abstract
The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) aims to provide “consistent and reliable acquisition, analysis, communication, and utilization of medical information through a single set of standards. Two physicians, following the methods of the [AMA] Guides to evaluate the same patient, should report similar results and reach similar conclusions.” In addition, the AMA Guides emphasizes that “[c]onsistency tests are designed to ensure reproducibility and greater accuracy.” If findings are inconsistent, the examiner may choose not to base an impairment rating on them, but, as with any biological measurements, some variability and normal fluctuations are inherent in permanent impairment ratings. Specifically, two measurements by the same examiner on two separate occasions or by two trained observers using the AMA Guides are consistent if they fall within 10% of each other. Repeated measurements may decrease error, and examiners should observe for consistencies in both behavior and findings. The musculoskeletal chapters of the AMA Guides provide specific directions in terms of consistency of measurements (eg, the number of measurements that should be taken using each test), allowable variations in measurements taken at different times, reproducibility of results on different occasions or by two or more trained observers, and the validity of these measurements. Inconsistent findings cannot be used to rate impairment.
Impairment Tutorial: Consistency in Measurement

Christopher R. Brigham

Pages 6–12

DOI: 10.1001/amaguidesnewsletters.2004.JulAug04

Abstract
The International Association of Industrial Accident Boards and Commissions (IAIABC) is an organization of medical directors, administrators, and administrative law judges for workers’ compensation systems. It was founded in 1914, and current membership represents 41 US states, the District of Columbia, Puerto Rico, 9 Canadian provinces, and 3 other governments in a forum for education and discussion regarding the various medical, legal, and administrative issues in workers’ compensation systems. In 2001, the IAIABC formed an Occupational Impairment Rating Guide Committee to study the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) and to suggest revisions specific to workers’ compensation. The committee's goal is to create a supplement to the AMA Guides for jurisdictions to consider for adoption to clarify and/or to replace methodology in the AMA Guides to make impairment rating more uniform and consistent. The IAIABC Guides has been developed to address impairment of the musculoskeletal system and impairment due to chronic pain with the goal of minimizing or eliminating the need for multiple independent medical evaluations and “dueling doctor depositions.” There are no plans to write supplemental guides for impairment of other body systems, and AMA and IAIABC are engaged in active dialog during the development of the AMA Guides, Sixth Edition.
Legal Update: An Alternative for Rating Impairment in Injured Workers

James B. Talmage

Pages 9–12

DOI: 10.1001/amaguidesnewsletters.2004.JulAug05

Articles

Apportionment Analysis

Case Study: Shoulder Injury

Question and Answer

Impairment Tutorial: Consistency in Measurement

Legal Update: An Alternative for Rating Impairment in Injured Workers