This article presents a case report regarding a 34-year-old obese male who works as a chipper and grinder at a steel manufacturing mill and uses high-frequency vibratory power tools. He presents with typical complaints of carpal tunnel syndrome, including numbness in all five digits, wrist pain, nocturnal awakening/numbness, and others. Two-point discrimination (2PD) using a caliper was tested in the digits of the upper extremities and was 5 mm throughout. 2PD first appeared in the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ), Fifth Edition, and the Sixth Edition states, “sensory deficits can be challenging to grade, since the clinical examination is based on subjective reports by the patient. Grading is based on the results of sensibility testing and two-point discrimination, to improve inter-rater reliability.” The discussion of “sensibility” involves a concept of sensory perception that is more appropriate in surgery literature than neurological literature, and the discussion of the case report in this article reflects the recent literature regarding 2PD as a measure of sensibility. The authors report that sensibility is not a simple recovery of sensory function following nerve injury but rather is a complex interaction between nerve recovery and modulation of central nervous system function in spinal cord, subcortical, and cortical structures. The authors ask if the value of 2PD in the clinical assessment of impairment has been overrated within the AMA Guides, as was range of motion in the assessment of spine impairment.

The terms subjective and objective often appear in health care records, and one commonly hears about “subjective symptoms” and “objective complaints”—yet the former is redundant and the latter an oxymoron. Objectively verifiable pathology may explain a patient's symptoms, but complaints themselves are never objective but rather, by definition, subjective. The AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ), Sixth Edition, defines the terminology: Subjective information is more open to interpretation, but objective data are factual, reproducible, and often measurable or quantifiable. Objective findings generally have much higher inter-examiner reliability than subjective findings. Symptoms and most findings on physical (particularly neuromusculoskeletal) examination are subjective. Diagnostic study results and a minority of physical findings are objective. Some physical findings, such as strength and range of motion measurements, are both subjective and objective. Repeat testing, assessment of plausibility, and use of confirmatory physical findings can be used to validate or “objectify” subjective findings (eg, by determining if a weakness is corroborated by other neurologic or physical findings, imaging study results, and/or electrodiagnostic testing). The use of objective, or at least less subjective, findings in impairment rating should improve interrater reliability. Thus, evaluating physicians should not regard subjective complaints and findings, and they should lend greater weight to objective findings.

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,” resulting in reliable, reproducible impairment ratings with high levels of interrater consistency. The authors reviewed 6233 impairment ratings that took place between July 2006 and January 2010 that reflected 11991 ratable diagnoses and found poor interrater reliability (78% disagreement rate). A previous study conducted in 2005 was published in The Guides Newsletter (May/June and July/August 2006 issues) and evaluated 2100 cases for impairment rating review and found that 80% of ratings resulted in different outcomes when reviewed by an expert reviewer. The current study found an average difference of 10.0% whole person permanent impairment (WPI) between the original WPI ratings calculated with the fifth edition and the revised ratings after expert review; the 2005 study found a similar difference, 9.9% WPI. The reasons for poor interrater reliability with fifth edition ratings are many and include inaccurate clinical and causation analysis, failure to use the AMA Guides appropriately, and bias. The error rate in this study was lowest for patients in Hawaii, where the AMA Guides, Fifth Edition, has been used since 2001, only a relatively small number of authors who have been trained in the use of the AMA Guides perform the evaluations, there is no systematic coaching by attorneys about how to use the AMA Guides, and impairment ratings are routinely reviewed to determine their accuracy.

In December 2007, the American Medical Association published the sixth edition of the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ), following previous editions published in 2000 (fifth edition) and 1993 (fourth edition). To assess the effects of changes in whole person impairment ratings across editions, the authors selected 200 cases of whole person impairment and reevaluated each according to criteria in the three editions. Interrater reliability was confirmed when an independent reviewer checked 15% of the cases and found agreement within 1% in all but one of the thirty cases checked. Tables and figures in the article compare average whole person impairment in terms of sixth edition chapters; by edition; and by category (nonsurgical vs surgical intervention) and edition. On the basis of the sample and their comparisons, the authors conclude that the effect for patients based on their diagnostic impairment is small, and greater difference is seen for results obtained using the fifth edition compared with the fourth edition. The observed changes were expected and result primarily from the following: surgery and therapy should improve function and thus should not routinely increase impairment; there are improved functional outcomes for carpal tunnel syndrome and total joint replacement; and certain common conditions that resulted in functional deficits but no ratable impairment in previous editions now should be ratable. The study showed excellent interrater reliability with sixth edition ratings, which was an important goal for the new edition.

In 2002, the Department of Labor and Employment, the State of Colorado, performed a study to identify changes among the Third Edition, Revised (December 1990); the Fourth Edition (June 1993); and the Fifth Edition (November 2000) of the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ). This three-part article summarizes the differences found. The study was based on a random sample of 250 cases identified by the Division of Workers’ Compensation of the State of Colorado and stratified into three broad categories: 40 upper extremity cases, 60 lower extremity cases, and 150 whole person cases. Only case records with adequate documented evidence to enable rating among all three editions of the AMA Guides were included. The average age of the examinee was 42.9 years (SD, 11.1 years, range, 18 to 71 years, 171 [68%] male); equal percentages of men and women were present in the upper extremity impairment ratings (20 men, 20 women), but lower extremity and whole person impairments occurred primarily among males (73% and 71% men, respectively). Interrater reliability was obtained from an independent expert medical review of 20% of the cases. Three figures show percentages of upper extremity, lower extremity, and whole person impairment according to the edition used; ratings generally are lower with more recent editions.

Early return to work is fundamental in the treatment of occupational injuries, but the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ) may require temporary or permanent work restrictions. The US Department of Labor Physical Demand Characteristics of work classifies jobs by exertional level (sedentary, light, medium, heavy, and very heavy). The Workplace Functional Ability Guidelines (WFAGs) consist of 21 categories of health impairment and emphasize what the worker can do, ie, the “functional ability.” Musculoskeletal symptoms and signs such as strength, range of motion, or radiographic findings are not good predictors of functional abilities, nor does standardizing the method for work-capacity determination. Measures of physical work performance, even when conducted by highly trained individuals, have low interrater reliability when used for complex tasks. Any discrepancy in expectations between the physician and worker about capabilities and anticipated progress should be resolved. This may be best done if the physician is familiar with the requirements of the job and can offer suggestions about, for example, reducing the stress on an injured body part by using a different model of a tool. Individual differences in motivation, pain tolerance, conditioning, and so on make it difficult to determine work restrictions, but physicians should attempt to return the worker to gainful employment as early as possible.

The AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides ), Fourth Edition, offers several categories to describe impairment in the shoulder, including shoulder amputation, abnormal shoulder motion, peripheral nerve disorders, subluxation/dislocation, and joint arthroplasty. This article clarifies appropriate methods for rating shoulder impairment in a specific patient, particularly with reference to the AMA Guides, Section 3.1j, Shoulder, Section 3.1k, Impairment of the Upper Extremity Due to Peripheral Nerve Disorders, and Section 3.1m, Impairment Due to Other Disorders of the Upper Extremity. A table shows shoulder motions and associated degrees of motion and can be used in assessing abnormal range of motion. Assessments of shoulder impairment due to peripheral nerve lesion also requires assessment of sensory loss (or presence of nerve pain) or motor deficits, and these may be categorized to the level of the spinal nerves (C5 to T1). Table 23 is useful regarding impairment from persistent joint subluxation or dislocation, and Table 27 can be helpful in assessing impairment of the upper extremity after arthroplasty of specific bones of joints. Although inter-rater reliability has been reasonably good, the validity of the upper extremity impairment rating has been questioned, and further research in industrial medicine and physical disability is required.

How should an individual with pain arising from muscle be rated using the AMA Guides to the Evaluation of Permanent Impairment ( AMA Guides )? Syndromes of muscle pain include simple muscle strains and two controversial conditions, myofascial pain and fibromyalgia. Tables in the AMA Guides can be used for rating forearm injuries that affect grip or pinch strength; a separate set of tables can be used to rate the injury in a lower extremity. Injuries to some muscles (deltoid, biceps, and triceps) are not described in these sections but almost always test as grade 4. Major injury to muscle is well understood and noncontroversial, but terms such as myofascial pain syndrome and fibromyalgia describe controversial muscle pains. Some physicians attempt to differentiate myofascial pain and fibromyalgia on the basis of taut bands in myofascial pain and tender points in fibromyalgia, but the interrater reliability of these findings is low and the consensus view suggests that the cause of these two conditions is unknown. Muscle pain, like muscle contraction headache, irritable bowel syndrome, and dysmenorrhea, are real symptoms for which no impairment rating is provided. Our understanding of these conditions should improve with future research, enabling us to define criteria for evaluating impairment.