Impairment Rating and Disability Determination

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Chapter 6 Impairment Rating and Disability Determination

Richard E. Seroussi, James P. Robinson

This chapter includes a brief introduction to the latest (sixth) edition to the American Medical Association (AMA) Guides to the Evaluation of Permanent Impairment,48 a reference text that can be likened to an updated tax code for impairment rating. The sixth edition chief editor is Robert D. Rondinelli, a physiatrist. In contrast to previous editions of the AMA Guides, it is fortunate that the sixth edition moves toward a more functional view of impairment rating.

This chapter provides basic information about disability and impairment evaluations. It covers four main topics:

1. The types of agencies that administer impairment and disability programs
2. The concepts central to this area of medicine
3. The physician’s role in performing these evaluations
4. Practical strategies for disability evaluation

While physicians of many different specialties are actively involved in disability and impairment evaluation, physiatrists have skills that are central to understanding disability and impairment evaluation. The physiatric emphasis on assessing and restoring function among the severely ill or injured provides a key component of what is typically needed by agencies requesting disability evaluations.

This chapter is not intended to be used to determine impairment or disability for a specific patient. The reader is referred in this regard to the AMA Guides,48 which outlines a method for rating impairment for virtually every organ system. In practical terms, however, most impairment and disability evaluations focus on musculoskeletal disorders.

Disability Agencies

During the past 100 years, the informal assistance within communities to help those with disabilities has been supplemented or replaced by formal disability programs. To receive benefits, an individual having a medical problem must submit an application to an agency that administers a disability program. Adjudicators from the agency then determine whether the applicant meets the eligibility criteria for benefits. To make this determination, the adjudicators typically request medical information from the applicant’s treating physicians. Physiatrists in particular are drawn into the disability determination process because they often treat patients with severe neurologic and/or musculoskeletal conditions. Disability and impairment systems include the Social Security Administration (SSA), workers’ compensation, the Veterans Administration (VA), and private disability insurance programs.

Impairment and disability are not absolutely defined and rated within a single system but are dependent on particular administrative systems. For example, workers’ compensation systems in the United States are no-fault insurance programs that are regulated at the state level and vary considerably from one state to another. Coverage is available for workers who have documented occupational injuries or “occupational exposures” (such as cumulative trauma disorders). Benefits can include medical care, time-loss benefit payments, vocational retraining if needed, and payment for impairment at the time of claim closure.

Assessment of impairment or disability must be done within the guidelines of an individual system. The term disability agency is used in this chapter to refer to any organization that evaluates disability applications or dispenses disability benefits.

Private disability agencies might award claimants who are no longer able to perform within their profession, but they might require that the claimant be unemployable in other professions as well. There is often a requirement of continuous disability of at least 6 months, and there can be an additional requirement that the claimant apply for and be eligible for Social Security Disability.

The SSA has its own set of guidelines for determining disability. If claimants are found eligible, they are awarded disability payments on an ongoing basis, as well as eligibility for Medicare or Medicaid. For claimants to be considered eligible for Social Security, they must be totally disabled from any gainful employment, and they must have an impairment that is considered “disabling” and likely to last or have lasted at least 12 months.

The VA has its own disability benefits program, described as follows:

Disability compensation is a monetary benefit paid to veterans who are disabled by an injury or disease that was incurred or aggravated during active military service. These disabilities are considered to be service-connected. Disability compensation varies with the degree of disability and the number of veteran’s dependents, and is paid monthly.60

Definitions: Disability and Impairment

Social Security Administration

Agencies have different definitions of disability. For example, the SSA defines disability as “the inability to engage in any substantial gainful activity … by reason of any medically determinable physical or mental impairment that can be expected to result in death or that has lasted or can be expected to last for a continuous period of not less than 12 months.”56 To determine work disability, the SSA uses a sequential evaluation process that focuses on applicants’ diagnoses, not their functional abilities. Although the SSA’s five-step process assesses earnings and impairment severity, it is not until late in the process that functional capacity is assessed. An applicant may appeal an unfavorable disability determination, which can markedly extend processing time. Unlike the VA, the SSA does not award benefits for “partial disability.”

The SSA disability programs influence the lives of millions of adults and children. As growing numbers of applicants apply for benefits, the agency is being pressured to meet very high demands. To improve the SSA’s determination process, an increased consideration of functional ability is likely needed.

AMA Guides, Sixth Edition

The latest edition of the AMA Guides48 uses as its foundation the World Health Organization model of disablement. This model is called the International Classification of Functioning, Disability, and Health (ICF) and is illustrated in Figure 6-1. There are three key inputs to the ICF model determining disability, paraphrased here from the AMA Guides48:

1. Body functions and body structures: These can vary from the normal state, and these losses are called impairments.
2. Activity: Task execution by the individual. Activity limitations are difficulties with carrying out such activities.
3. Participation: Involvement in life situations. Participation restrictions are barriers from such involvement.

Note that body functions are physiologic—for example, the ability of the upper limb to generate accurate motion and strength. Body structures are anatomic—for example, the upper limb itself. Either or both can be compromised to produce impairment. The inability to carry out tasks, such as not being able to comb one’s hair, is an activity limitation. The inability to be involved in a typical life situation, such as being gainfully employed and interacting with one’s peers, is a participation restriction. Note that there is not a necessary correlation between activity limitation and participation restriction.

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FIGURE 6-1 The World Health Organization ICF Model of Disablement.

(Redrawn from Rondinelli RD, editor: Guides to the evaluation of permanent impairment, ed 6, Chicago, 2008, American Medical Association Press.)

In the ICF model, there is no linear progression from pathology to impairment to disability and to participation restriction. The AMA Guides justifies the use of the ICF model as follows48:

The ICF model appears to be the best model for the Guides. It acknowledges the complex and dynamic interactions between an individual with a given health condition, the environment, and personal factors. The relationships between impairment, activity limitations, and participation are not assumed to be linear or unidirectional. An individual may experience measurable impairment without significant activity limitations that do not produce restrictions to major life activities such as work or recreation. On the other hand, one can experience significant activity limitations and/or participation restrictions in the absence of demonstrable impairment.

The reader should note that this framework for distinguishing impairment from disability is natural for the physiatrist. As medical professionals, physiatrists have core training in diagnosing and treating loss of body function and structure, but they also ask about the ability of patients to control their environment. Specifically, physiatrists focus on mobility deficits, including ambulation and transfers, and on activities of daily living (ADLs), including instrumental ADLs. Using the ICF framework, the AMA Guides defines impairment and disability as follows:

Impairment: A significant deviation, loss, or loss of use of any body structure or body function in an individual with a health condition, disorder, or disease.

Disability: Activity limitations and/or participation restrictions in an individual with a health condition, disorder, or disease.

Impairment rating within the latest AMA Guides10 has more weight given to loss of function in the determination of impairment rating. This is defined as a “consensus-derived percentage estimate of loss of activity reflecting severity for a given health condition, and degree of associated limitations in terms of ADLs [italics added].”

This chapter is not meant to provide the reader with the necessary skills to do actual impairment ratings, which can be fairly complex and detailed. However, a brief sketch of the approach to impairment rating based on the latest AMA Guides is given here48:

• There are four impairment criteria defined within the AMA Guides, with some clarification given for each criterion:

1. History of clinical presentation (the overall clinical diagnosis)
2. Physical examination (physical examination findings at the time of impairment rating)
3. Clinical studies and objective tests (e.g., imaging studies, blood work, and electrodiagnostic studies)
4. Functional assessment or history (self-reported ability to function from the patient, with a functional assessment scale preferably used such as the Pain Disability Questionnaire)

• The first task of an examiner is to assign a claimant to an impairment class on the basis of the above kinds of data. An impairment class broadly brackets the percentage impairment that the claimant might be awarded. For most conditions, the classes are as follows:

• Class 0: No objective problem
• Class 1: Mild problem
• Class 2: Moderate problem
• Class 3: Severe problem
• Class 4: Very severe problem

• In assigning a claimant to an impairment class, the physician relies upon a “key factor,” one of the four impairment criteria listed above. Typically the key factor leading to a claimant’s assignment to a particular class is the diagnosis (i.e., history of clinical presentation). However, a different key factor, such as diagnostic testing for cardiac conditions, might be relied upon for different organ systems. Each impairment class is associated with a range of possible whole-person impairment percentages.
• To arrive at a precise percentage of whole-person impairment, the examiner fine tunes the impairment rating by assigning an impairment grade within the assigned class. Grades range from A (when claimants are substantially less impaired than most people in their impairment class) to C (when the degree of impairment of claimants is average for people with their impairment grade) to E (when claimants are substantially more impaired than most people in their impairment class). The “default grade” is C; this is the grade that an examining physician should assign when there is no compelling evidence to support a higher or lower grade.
• To determine a claimant’s impairment grade, the examiner relies upon the “non–key factor” impairment criteria. Given that the key factor is generally the diagnosis (history of clinical presentation), these other criteria are physical examination findings, clinical studies, and functional history. If these impairment criteria suggest more severe impairment than the class chosen by use of the key factor, the examiner cannot change the chosen class; however, the examiner can choose a higher grade within the class (i.e., grade D or E), resulting in a relatively higher whole-person impairment. In the example of a cervical spine impairment rating for intervertebral disk herniation or documented alteration of motion segment integrity (AOMSI), there are five impairment classes (Table 6-1).
• Class 2 for the cervical spine example given here is for “intervertebral disk herniation and/or AOMSI at a single level with medically documented findings; with or without surgery AND with documented radiculopathy at the clinically appropriate level present at the time of examination.”
• More severe related cervical spine disorders are rated class 3 or 4 (e.g., multilevel active radiculopathy), and less severe cervical spine disorders are given class 0 or 1 (e.g., resolution of radiculopathy).

Table 6-1 Simplification of AMA Guide’s Cervical Spine Regional Grid for Impairment Rating

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Note that there is a new emphasis on functional history with this edition of the AMA Guides. Loss of function is assessed in part by self-report measures that claimants may fill out at the time of their impairment evaluations. Different measures are used for different kinds of disorders; for example, the QuickDASH is used for disorders of the hand, while the Pain Disability Questionnaire is used for evaluating functional limitations involving the spine. The important general point is that impairment ratings in the AMA Guides sixth edition incorporate subjective information from claimants about their burden of illness. The significance of this change in the Guides is modest, however, because functional history plays a relatively minor role, modulating the grade within a given class. The primary emphasis in the Guides continues to be on objective findings rather than subjective history in the impairment rating process.

Further Thoughts on Impairment Versus Disability

Disability agencies typically assume a strong linkage between impairment and disability and assume that impairment is a necessary condition for disability. The logic underlying this requirement is straightforward. Disability programs are designed to assist individuals who are unable to compete in the workplace because of a medical condition. In essence, disability programs attempt to partition individuals who fail in the workplace into two broad groups: those who fail because of a medical condition, and those who fail for other nonmedical reasons. There are many potential nonmedical reasons, including a lack of demand for their skills or a lack of motivation. Disability programs require evidence that applicants have a medical problem underlying their workplace absence. Impairment provides the needed evidence, because it can be viewed as a marker that individuals have a medical problem that diminishes their capability. Conversely, if individuals have no identifiable impairment, they are assumed to have no workplace limitations caused by a medical condition.

Disability agencies typically assume that the severity of patients’ impairments correlates with the degree and/or probability of their being disabled from work. Even when an agency compensates for work disability and not for impairment, it will often seek information about a patient’s impairment to rationalize its decision about whether to award disability benefits. As will be discussed, the assumption that increasing impairment leads to increased disability can be challenged when quantifying impairment. Certainly the linear correlation between the level of disability and impairment is often absent. Physiatrists should educate others, including case managers, physicians, and attorneys when applicable, about these imperfections.

Whereas it is possible to distinguish conceptually between impairment and disability, the distinction is not always clear in many practical situations. For example, the notion of a measurably dysfunctional organ does not readily apply to psychiatric impairments. Although the distinction between impairment and disability is easy to make in some medical conditions, it is difficult to make in others.

Another problem is that the correlation between severity of impairment and severity of disability is far from perfect, as illustrated in the following examples:

• A patient might have serious impairment yet very little apparent vocational disability. A striking example is that of the world-famous physics professor, Dr. Stephen Hawking. He is incapacitated from the most basic ADLs because of motor neuron disease, and would qualify for a very high total body impairment according to the AMA Guides. However, he is not work disabled. In fact, he has remained active as a theoretic physicist of international acclaim well beyond the onset of motor neuron disease in his 20s. Within the ICF framework, Dr. Hawking would have almost complete activity limitations, but notably fewer work-related participation restrictions.
• A patient might have a very mild ratable impairment, as measured through the AMA Guides, from a lumbar or cervical facet injury as a result of a motor vehicle crash. However, such an injury can cause devastating vocational consequences if the patient has a job that requires constant heavy physical labor. Such a patient might even be rated as having “no impairment” according to some examiners, because of a lack of a demonstrable disk herniation with advanced imaging or a lack of radicular findings on examination, or both. When subjected to a functional capacity evaluation, the patient might be shown to be truly incapable of doing heavy physical labor. Consequently, such a patient could be considered 100% disabled from such labor and yet might have little or no ratable impairment according to some examiners’ interpretations of impairment rating guidelines.
• A patient might have had a demonstrable disk herniation with radiculopathy and responded well to spinal surgery. According to both the AMA Guides and a number of workers’ compensation guidelines, this patient would have significant whole-body impairment. Despite this impressive level of impairment, this patient might have little or no disability in terms of work role and ADLs.
• As a final example, the patient could have a well-defined impairment—amputation of the fifth digit of the nondominant hand. This type of amputation is very well described in the AMA Guides, but the patient’s disability, if any, will be strongly dependent on the patient’s profession. If the patient were a concert pianist, the disability might be 100%. If the patient were a psychiatrist, there would likely be no disability. If the patient were a construction worker, the disability would likely be minimal, mild, or possibly moderate, depending on the individual tasks that had to be performed.

Roles of Physicians in Disability Evaluation

Some physicians become expert in disability evaluation and make disability evaluation a central part of their clinical practices. Some function as consultants to other physicians when they perform disability evaluations. Other physicians with an interest in disability evaluation perform independent medical examinations (IMEs) that are commissioned by insurance carriers, disability agencies, or attorneys. Still others work as employees of disability agencies or insurance companies. As part of this work, they might perform disability evaluations by directly examining claimants. More typically, however, such consultants play a variety of indirect roles—for example, advising claims managers when to order IMEs, or reviewing IMEs that have been performed.

Many physicians do not seek opportunities to perform disability evaluations because they are uncomfortable evaluating disability in patients whom they are treating. They correctly perceive that the process of disability evaluation places a physician between the interests of the patient and those of an insurance company or disability agency. In the best of circumstances, this can seem to the physician like trying to fit a round peg into a square hole, because the categories of disability established by such agencies often do not match the clinical realities of patients.

In the worst case, clinicians end up feeling caught in the crossfire between adversaries. They may perceive employees of disability agencies as unenlightened bureaucrats who make excessive demands for documentation. On the other hand, they may perceive their patient as reporting excessive incapacitation and trying to enlist physicians as allies in their battle to legitimize their disability.

The concerns that treating physicians have about doing disability evaluations appear to fall into two categories: knowledge deficits and ethical concerns. Physicians who work primarily as clinicians are likely to be unfamiliar with the disability laws and regulations relevant to their patients, and the disability agencies that administer them. They are also likely to lack expertise in the mechanics of rating impairment, such as those detailed in the AMA Guides,48 and in the methods that can be used to assess work ability.20,21,31,33,49

Treating physicians can be concerned about conflicts between the clinical role they normally play when they treat patients and the adjudicative role that is required during a disability evaluation. Informal observation as well as examination of the limited literature on these roles26,42,58,65 suggests several differences between the two roles. For example, physicians performing disability evaluations are expected to focus on objective findings and legal responsibility, including causation, for an examinee’s disorder, but these are not the main concern of physicians when they provide clinical treatment.46 As Sullivan and Loeser58 have noted, significant ethical issues arise when physicians switch back and forth between these two roles.

Assessing Self-Reports of Patients Regarding Physical Capacity

A key challenge is to combine examinees’ self-reports regarding their incapacitation with objective medical information relevant to their injury.47 Note that the definition of “objective medical information” is not always clear. Unfortunately the existence of objective medical findings often depends on the degree to which technologies have advanced. For example, before myelography became available, radiographic studies (i.e., x-ray films) did not demonstrate objective findings for patients with radiculopathies.

A second problem is that a high level of interrater reliability is a necessary condition for objectivity in any endeavor. However, in the arena of impairment and disability evaluation, it is common for different examiners—many of whom consider themselves to be “forensic experts”—to generate disparate conclusions about the same patient.

One way for a physician to resolve potential discrepancies between self-report data and objective findings is to accept at face value what patients say about their physical capacities. A physician adopting this strategy would run the risk of underestimating the rehabilitation potential of individuals who overstate their incapacitation either deliberately, as in the case of malingerers, or as a result of genuine misperceptions regarding their abilities. At the opposite extreme, a physician might make decisions about the disability status of patients strictly on the basis of what they perceive to be “objective findings,” and react skeptically to reports of incapacitation that are not closely linked to these findings.

A position somewhere between these two extremes is probably most appropriate. The perceptions that patients have about their abilities certainly should not be ignored or discounted. As a practical matter, research demonstrates that these self-appraisals are important predictors of whether patients with pain problems will perform well on physical tests or will succeed in terminating their disability, or both.14,15,23–25,30 Physicians who make disability decisions without considering patients’ appraisals are discarding valuable data. As a result, their decisions can go awry in two ways. First, they can pressure patients to return to work in jobs that the patients are realistically not capable of performing. Second, they can be ineffective in resolving disability issues. Consider patients who are released to work by their treating physician or by an independent medical examiner even though they are convinced that they are unable to work. Such patients are likely to retain an attorney and start a protracted legal battle regarding their work status.

But the fact that patients’ perceptions are important does not mean that they are valid or immutable. In fact, research on patients with disability related to chronic pain suggests the opposite: some often have distorted views of their capabilities, and these views are modifiable.1,12,28,35 Disability evaluators need to consider the validity of a patient’s stated activity limitations in light of the biomedical information available and their assessment of the patient’s credibility. Evaluators should reserve the right to challenge the patient’s self-assessments and to make decisions that are discordant with these assessments.

In summary, the treating physician should carefully assess examinees’ perceptions regarding their ability to perform various tasks and, whenever feasible, should take them into account when rendering judgments about their ability to work. But the physician should not let examinees control the discussion about disability. Instead, physicians should be ready to challenge the appraisals of examinees when they believe them to be inaccurate.

Blending Administrative Imperatives With Patient Realities

Disability agencies and insurance companies follow what might be called an administrative imperative as they adjudicate disability claims. The imperative is to reach decisions about disability benefits for applicants on the basis of procedures that are objective, consistent, and efficient. These goals are reasonable, but they can lead agencies to oversimplify the process. The “administrative model” of injury and disability is most apparent in workers’ compensation systems. It typically assumes the following:

• Incapacitation after an injury should be should be “transparent” to a physician; that is, activity limitations described by patients should be highly correlated with evidence of tissue damage or organ dysfunction objectively assessed by a physician.
• Recovery after trauma follows a fairly predictable course, such that an injured worker initially shows progressive improvement and then reaches a plateau or fully recovers (Figure 6-2). In compensation law, workers are said to be “fixed and stable” or to have reached “maximal medical improvement” when they reach this plateau. At this juncture, compensation law generally dictates that medical treatment be terminated, and if patients are not able to return fully to their job after injury, either a definitive vocational plan needs to be developed or they should be pensioned.
• Work injuries typically occur when a previously healthy individual is exposed to an obvious and overwhelming source of trauma, such as a fall from a height or a crush injury from a heavy object.
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FIGURE 6-2 Hypothetical recovery curve after an injury.

The assumption of transparency is problematic. This assumption is so pervasive that most physicians, and essentially all disability adjudicators, accept it without question. From a historical perspective, however, it is apparent that physicians have not always believed that incapacitation from trauma should be transparent. In fact, when the Social Security Disability Insurance (SSDI) program was being considered by Congress during the 1950s, physician groups almost uniformly protested that they would not be able to do the assessments that were envisaged in the SSDI legislation.41

For some impairments, objective criteria can be used in a transparent manner. For example, physicians have straightforward tools to quantify impairment stemming from amputations, complete spinal cord injuries, or clear cases of radiculopathy that are supported by magnetic resonance imaging (MRI) evidence of a focal disk herniation. However, in many medical conditions, including many musculoskeletal and neurologic disorders, physicians cannot easily identify injuries to organs or body parts that lead to the activity limitations that examinees report. Again the example of spinal facet joint injuries is given. Carefully controlled studies since the 1990s have documented that cervical facet joint injury is the probable primary pain generator for 50% of whiplash patients with nonradicular neck pain.2,3,37

More recently, animal and postmortem biomechanical studies of cervical facet joint injury have strengthened these clinical findings by documenting posttraumatic facet capsular laxity,27 as well as pain behavioral changes34 and histologic axonal changes29 in animals exposed to facet joint distensions simulating whiplash injury. Despite these advances, documenting facet joint injury for impairment rating remains problematic. Although cervical facet joints show up on MRI scanning, injury to them, or pain stemming from them, is generally not detected. Conversely, facet joint arthropathy, when detected with imaging studies, can be seen among asymptomatic patients and cannot be taken as a reliable physical sign of facet joint injury or impairment.52,54 There are guidelines for giving impairment for motion segment instability, which might be associated with increased facet capsular laxity, but the threshold for giving impairment for such instability is likely not sensitive.

In addition, there is increasing evidence that patients with chronic whiplash pain, chronic low back pain, or both, develop changes in central nervous system functioning that augment the severity of their chronic pain.11,18,32,57 These changes are also difficult to quantify but can become the basis for significant loss of function and vocational disability. Disability evaluators cannot easily rate impairment for this common clinical scenario. More importantly, they cannot offer a clear correlation between severity of impairment and severity of disability.

In the latest AMA Guides, facet injury after whiplash is formally acknowledged for the first time as a ratable impairment.48 However, it is grouped as “nonspecific chronic, or chronic recurrent neck pain (also known as chronic sprain/strain, symptomatic degenerative disk disease, facet joint pain, chronic whiplash, etc.).” This carries a maximum 8% whole-person impairment.

By contrast, a patient who has a documented severe facet joint injury resulting in facet joint neurotomy might become disabled from heavy physical work, require vocational retraining, and might become dependent upon repeated neurotomies indefinitely at approximate 8- to 12-month intervals for adequate pain relief.53 This can represent a huge burden of future medical and vocational costs projected over the person’s lifetime.

On the other hand, a patient could have had two cervical disk herniations causing multilevel radiculopathy, with good response to neck surgery. This patient would be left with a minimum of 15% whole-person impairment, almost twice the impairment of the patient with the facet joint injury. Moreover, the patient with radiculopathy would have far lower, if any, future medical and vocational costs. Clearly the impairment rating process continues to be imperfect at best. It is up to clinicians to carefully weigh these paradoxes when giving opinions regarding impairment and disability.

Even in the case of radiculopathy, a condition thought to be fairly well assessed within the AMA Guides, there are pitfalls for assessing spinal impairment. Research has shown that most lumbar MRI findings among patients with radiculopathy do not correlate well with their pain diagrams and physical examination findings, except in the rare case of a disk extrusion or severe spinal stenosis, or both.4 In practice, most MRI findings do not demonstrate such severe pathology. In addition, there is increasing understanding that radiculopathy is an inflammatory condition and might not depend on demonstrable nerve root compression by MRI scanning. There can be clear clinical evidence of radiculopathy causing significant functional impairment in the absence of MRI-detected nerve root compression.55,64

These examples highlight two problems. First, it is can be difficult to identify an anatomic or physiologic abnormality that rationalizes the claim of incapacity. This problem occurs frequently. For example, data from the U.S. Department of Labor, Bureau of Labor Statistics indicate that more than 40% of work injuries requiring time off work are coded as sprains/strains.59 Although such injuries might be supported by objective findings, such as a complete tear of the anterior cruciate ligament documented by MRI scan, physicians often diagnose a sprain/strain when a patient complains of pain without well-defined objective findings. Second, a given structural abnormality might be associated with a wide range of functional loss among different patients. In this regard, it is worth noting that there is little empirical evidence to validate the quantitative impairment percentages given in the AMA Guides.

Topics Addressed in Disability Evaluations

Physicians are typically asked to address the following when they conduct disability evaluations:

• Diagnosis
• Causation
• Need for further treatment
• Impairment
• Activity limitations and functional capacity
• Ability to work (i.e., work disability)

A fundamental goal of the disability evaluation process is to determine whether a patient can work. From this perspective, the first five items can be viewed as preliminary items that set the stage for addressing the sixth and crucial question.

Practical Strategies for Disability Evaluation

The discussion below is largely based on our experiences treating patients in clinical settings, performing independent medical examinations, and consulting with the Washington State Department of Labor and Industries. Scientific data on the reliability and validity of disability evaluations are limited.7–944 In the absence of scientific data, it is impossible to say what decision-making strategies are appropriate when performing disability evaluations. In this ambiguous situation, it is easy for practitioners to fall into the trap of believing they are making valid judgments, when in fact their judgments are based on a variety of biases.19,46

Addressing the Main Questions

Diagnosis

Of the issues commonly addressed in a disability evaluation, diagnosis is the only one that the physician considers in a routine clinical evaluation of a patient. Even here, complications arise when disability evaluations are performed. As an example, adjudicators sometimes make inferences about causation on the basis of a diagnosis. Note that if a physician diagnoses lumbar degenerative disk disease (International Classification of Diseases 722.52) in a patient, an adjudicator might take the position that the patient’s back pain was not caused by a specific injury.

Causation and Apportionment

The issue of causation is important because many disability agencies will only give benefits for medical conditions that arise from specific causes. For example, workers’ compensation carriers are responsible only for work-related medical conditions, and automobile insurance carriers are responsible only for injuries that occur in motor vehicle accidents. Although causation is straightforward for many injuries, a number of pitfalls can arise.

First, patients might have cumulative trauma disorders, which would be the result of an “occupational exposure” rather than a specific injury. In this setting, especially if the injured worker has had multiple employers during the period when the exposure appears relevant, the issue of how to distribute liability becomes critical. In this case, there is a need for apportionment. Apportionment is an attempt to distribute causation among multiple possible sources. In the latest edition of the AMA Guides, apportionment is described as “an allocation of causation among multiple factors that caused or significantly contributed to the injury or disease and resulting impairment.”48

In the current example of a cumulative trauma disorder, it might be determined that approximately 60% causation should be apportioned to the patient’s employer of the past 3 years and 40% to the patient’s prior employer, based on a history of repetitive use of the upper limbs during both periods of employment. As one can imagine, apportionment is a very approximate process and fraught with disagreements among experts. For example, a patient who has undergone a lumbar diskectomy in the remote past might report a return of radicular symptoms after a fall. In this setting, a disability agency could ask the physician to apportion causation of the patient’s impairment between the index injury and the patient’s preexisting lumbar disk condition. It is often useful to distinguish between inactive and active preexisting conditions when considering apportionment. But even here, defining a set time interval before a causative event as the threshold of when a preexisting condition is active or inactive is not standardized. Should it be 3 months, 6 months, or 2 years, or should every preexisting condition no matter how remote in the past be considered relevant to the issues of causation and apportionment?

Disability agencies differ significantly in the standards they set for establishing causation and the need for apportionment. Some agencies follow the principle that for an index injury to be accepted as the cause of a patient’s impairment, the injury must be the major factor contributing to the impairment. Others adopt a lower standard of causation that has been described as “lighting up.” When this standard applies, an index injury can be viewed as the cause of increased impairment even when the injury is minor and when preexisting impairment is severe. For example, consider an individual with a multiply operated knee who falls at work, develops an effusion in the knee, and is told by an orthopedist that he needs a total knee replacement. If the individual’s workers’ compensation carrier operated under the “lighting up” standard of causation, this person’s knee symptoms and need for a total knee replacement would be viewed as caused by the fall at work.

When there is a preexisting condition, the physician should ideally apportion in at least three areas when doing a forensic evaluation regarding impairment and disability:

1. Apportionment for the need for care: This attempts to answer whether, on a more probable than not basis, the claimant would have required treatment (often already paid within a claim) if the index injury had not occurred. In other words, in the absence of the index injury, how much care, if any at all, would the claimant have required for the treatment of an active or inactive preexisting condition?
2. Apportionment for impairment: This attempt to split the total current impairment between a preexisting component and that which has been created by an index injury. In the example of the patient with a multiply operated knee, there might be significant preexisting impairment, although the need for care for the preexisting condition may be minimal or zero were it not for the index injury.
3. Apportionment for disability: This is usually taken to mean work disability, which is generally compensable, but can be extended to disability from ADLs. This again draws a distinction between the effects of an injury on the level of impairment versus one’s ability to function in everyday life. In the setting of a significant preexisting impairment, marginally increased impairment from a new injury might cause, or might be alleged to cause, significant work disability.

Apportionment analysis is most commonly described for impairment only48 and is determined by subtracting preexisting impairment, with respect to an index injury, from the current impairment. It is clear, however, that apportionment analyses for the cost of care and for disability are critical to the successful adjudication of compensable claims.

Take the example of an actual patient who has had three previous neck surgeries, including two fusions, who is undergoing active conservative pain management, and then is involved in a motor vehicle crash. After the crash, the patient required a partial hardware removal procedure from a previous fusion. A careful analysis revealed that, on a more-probable-than-not basis, this hardware removal would not have been necessary were it not for the motor vehicle crash. This cost of care was therefore covered by the motor vehicle claim, but it was clear that the patient had the majority of the cervical impairment as preexisting, when compared with her overall impairment after she reached maximum medical improvement from the effects of the crash. She also had neck care costs that were independent of the motor vehicle crash history.

Some of the factors that help with a credible apportionment analysis include:

• Obtaining a functional history from these patients, which includes understanding their current ability to perform ADLs, vocational activities, and recreational activities as compared with before an index injury.
• Judging the credibility of the functional history. Do the medical records support the patient’s contention that there has been a loss of function? Some patients might not consciously fabricate their stated loss of function, but could be mistaken, given that years have passed since the index injury. For example, a patient might claim that a weight gain of 40 lb was caused by inactivity from the index injury. The medical record, however, might reflect otherwise, and there might be only a few pounds gained. Ideally, these patients should be directly confronted with these data, and the examiner should try to gauge whether they appear truly mistaken or are being consciously deceptive in their history.
• Carefully examining preexisting medical records, including a timeline for the need for care, work restrictions, and if applicable, preexisting impairment ratings. A study by Eugene Carragee6 in 2008 documented that self-report by patients regarding preexisting axial back or neck pain after a motor vehicle crash is often underreported. Consequently, scrutiny of preexisting medical records and careful interviewing of the patient become more important when determining causation in this setting.

In summary, when considering apportionment, the examiner should address the following three critical questions: Were it not for the index injury, on a more-probable-than-not basis, (1) what would be the patient’s need for medical care since the date of the index injury? (2) what would be the patient’s current level of impairment? and (3) what would be the patient’s current disability (including inability to engage in gainful employment)?

Need for Further Treatment

Disability agencies generally adopt an idealized model of the course of recovery after an injury. This model is shown in Figure 6-2. It embodies the assumption that people show rapid improvement after injury but then reach a plateau. Before patients reach this hypothetical plateau, they presumably can benefit from further treatment. When they reach the plateau, they are considered to have achieved maximal medical improvement (MMI). When a patient has reached MMI, insurance companies and disability agencies typically refuse to pay for additional medical care and attempt to make a final determination regarding a patient’s impairment and work capacity. From an administrative perspective, the model is convenient because it provides guidelines for intervention and decision making. For example, when a patient has reached point X on the graph, curative treatment should be abandoned, and a permanent partial impairment rating should be made.

The problem with this approach is that patients frequently have clinical problems that are hard to conceptualize in terms of the idealized recovery shown in Figure 6-2. First, it is not clear that patients with repetitive strain injuries or chronic spinal pain39,61 follow the trajectory shown in Figure 6-2. Second, patients can have comorbidities that complicate recovery and make it difficult to determine when they have reached MMI. An example is a patient with diabetes who has a work-related carpal tunnel syndrome in addition to a peripheral polyneuropathy. Third, many who use the MMI concept fail to remember that a patient who has reached maximal benefit from a particular kind of treatment might not have reached maximal benefit from treatment in general. For example, consider a patient who is examined 6 months after a low back injury. Assume that treatment has consisted entirely of chiropractic care during the 6-month interval, and that the patient has not shown any measurable improvement during the past 2 months. This patient might be judged to have reached maximal medical benefit from chiropractic care, but an examining physician would understandably be uncertain about whether the patient could benefit from physical therapy, epidural corticosteroids, lumbar surgery, aggressive use of various medications, or other therapies that might not be offered by the chiropractor. This problem is not just a hypothetical one, because examiners routinely find that some patients with chronic conditions have not had exposure to all reasonable treatments for their condition.

At times it is more sensible to state that the patient has reached MMI with respect to specific care. For example, the statement “the patient has reached MMI with respect to conservative care options” would likely be more accurate than simply stating the patient is at MMI. If interventional care options are not appropriate, then the patient might truly be at MMI with respect to all reasonable care options.

Finally, disability and health insurance companies typically take the position that no more medical treatment should be authorized after a patient has reached MMI. This administrative perspective frequently does not match the clinical needs of patients. For example, a patient may have reached MMI from a low back injury in the sense that a significant period has elapsed since injury, and no further curative treatment is available. However, the individual might still need maintenance treatment, such as ongoing medication, for the back injury. This issue is often ignored by agencies that administer benefits.

A workers’ compensation company might state that such maintenance treatment is “palliative” and not curative, and therefore not covered within the claim. One interpretation of this distinction might view dialysis as “palliative” and not curative because it does not cure the patient from the loss of kidney function. And yet dialysis would likely be covered indefinitely within a claim. Might one also argue that long-term medication or massage, although likely palliative, should be covered for chronic spinal pain if dialysis is covered for renal failure? These are ethical issues that raise more questions than they answer.

Impairment

Physicians need to decide when to perform an impairment rating. For example, an impairment rating would not be appropriate for a patient who has not reached MMI, or (at least in workers’ compensation cases) for a patient whose injury was not causally related to a work exposure.

Once a physician decides that an impairment rating is appropriate for a patient, the rating itself is a fairly mechanical task that is based on formulas and procedures described in various texts, or in manuals published by disability agencies. The agency that requests an impairment rating typically specifies the system that physicians are required to use. For example, the AMA Guides48 describes an impairment rating system that is used by multiple jurisdictions. Some states have their own impairment rating systems. To perform an impairment evaluation according to the rules of a jurisdiction, the physician needs to be familiar with the system used by that jurisdiction.

Physical Capacities Assessment

The assessment of physical capacities is a precursor to the determination of a patient’s ability to work. Disability agencies typically request detailed physical capacities data and usually provide supplementary forms for this purpose. In general, a clinical evaluation in the physician’s office will not provide detailed physical capacities information. The physician can supplement information gleaned from a clinical evaluation in a few ways.

The simplest way is to ask patients to estimate their physical capacities. The physician should consider filling out a physical capacities form on the basis of a patient’s reports if the patient is judged to be highly credible, or if the physician does not have access to objective data regarding the patient’s capacities. The physician who follows this approach should indicate this on the form.

Another way to obtain physical capacities data is to refer a patient for a functional capacities evaluation (FCE), also called a performance-based physical capacities evaluation.31,33,49 FCEs are formal, standardized assessments typically performed by physical therapists. They usually last from 2 to 5 hours. The therapist gathers information about a patient’s strength, range of motion, and endurance in various tasks, preferably ones that simulate the type of work that the patient is expected to do. As noted by King et al.,31 FCEs are popular with insurance carriers and attorneys because they provide objective performance data. In their comprehensive review, however, King et al. also noted that there is a paucity of data that validate FCEs against actual job performance.

Pransky and Dempsey43 noted that a generalized FCE has less utility than one simulating a specific job requirement, in terms of predicting actual job performance. However, tailoring the FCE process to a specific job requires more resources and is likely not practical in most scenarios. Gross and Battie20–22 noted that for both patients with low back pain and those with upper limb disorders, FCE results are poor predictors of termination of time loss benefits and return to work. Clearly, psychological factors and coping skills play an important role in predicting return to work, and these variables are not well captured within a standardized FCE.

Despite these limitations, FCEs likely have a role in determining loss of anatomic functions, such as range of motion and loss of strength, and these are important inputs into the determination of impairment. Also, in at least one author’s experience (R.E.S.), the FCE results correlate fairly well with broad clinical estimates of a patient’s physical capacities that are established by the treating physiatrist. The attending physiatrist’s estimates might be likened to a watercolor sketch, and the FCE to a finished oil painting of the same scene.

The FCE can also gauge the level of the patient’s effort, to help address the possibility of malingering, secondary gain, or excessive fear of exertion after injury. As an example, full effort is assumed if the coefficients of variation—the standard deviation divided by the mean as a percentage—are less than 10% to 15% for repeated hand grip measurements blinded from the patient. As discussed in a recent review,43 however, the ability to detect submaximal effort is imperfect at best.

A few definitions are helpful in understanding the language of physical capacity or functional capacity evaluations. These are derived from the Dictionary of Occupational Titles, published by the U.S. Department of Labor. Generally, the following are categories describing the “frequency of activity”:

• None (0% of the time)
• Occasional (1% to 33% of the time)
• Frequent (34% to 66% of the time)
• Constant (67% to 100% of the time)

In practice, a category between none and occasional is useful, described as “Seldom” or “Rare,” which is defined as 1% to 10% of the time. Also available from the Dictionary of Occupational Titles is a broad definition of job categories by physical lifting requirements (Table 6-2).

Table 6-2 Dictionary of Occupational Titles Categories of Job Physical Requirements

image

There are other considerations within these categories, including the amount of required standing or walking, as well as considerations of bending, twisting, and other postural demands. Consequently, a broad clinical estimate of physical capacities for a patient with combined neck, right shoulder, and lower back injuries might be as follows:

• Postural breaks every hour as needed
• Occasional bending, twisting, stooping, and kneeling
• Lifting and carrying up to 20 lb occasionally, approximately half that weight frequently
• Reaching overhead with right upper limb on a rare basis only

Overall this estimate of physical capacities falls within the light work category, although some further restrictions are given for the right shoulder. If more refined estimates of physical capacities or if a more detailed assessment of whether the patient is giving full effort is needed, an FCE could be obtained and checked against these clinical estimates.

Ability to Work

The ability of a patient to work is the key issue in most disability evaluations. Assessing employability is difficult, and there is no simple set of techniques to apply when a decision about employability is requested. Box 6-1 outlines issues that should be considered when judging a patient’s employability.

Box 6-1 Issues to Consider in Determining Employability

1. What specific questions about employability are you being asked to address?

a. Can the patient work at a specified job?
b. What general category of work can the patient perform (sedentary, light, medium, heavy, very heavy)?
c. Is the patient employable in any capacity?

2. For work in a specific job:

a. Is there a job analysis?
b. Does the patient agree with the demands stated on the job analysis?
c. Are there any collateral sources of information about the job (e.g., information from the employer)?
d. Do you believe the patient can perform the job with modifications?
e. Do you believe the patient needs assistance in transitioning to the job (e.g., a graduated reentry or a work-hardening program?

3. Do you have reliable physical capacities data that permit you to determine the appropriateness of a specific job or the appropriateness of a general work category?
4. Are there any “trick questions”?

a. Description of a job with minimal physical requirements (e.g., phone solicitor)
b. Description of a job that seems inappropriate for the patient from an economic and career standpoint (e.g., description of a cashiering job for a person who has spent the last 20 years working as an electrician)

5. Based on the questions addressed to you, does it seem that the disability agency is making a sincere attempt to find a place in the workforce for the patient, as opposed to trying to “set the patient up” (i.e., contrive vocational options that will maneuver him or her out of the disability system)?
6. Does it appear that the patient is making a sincere effort to return to work, or is the patient exaggerating pain complaints and/or maneuvering in some way to get long-term disability?

A physician makes a judgment about a patient’s employability by balancing the patient’s functional capacities (or limitations) against the functional demands of jobs for which the patient is being considered. Concerning job demands, the physician usually has to rely upon information provided by vocational rehabilitation counselors or employers. In workers’ compensation claims, vocational rehabilitation counselors often prepare formal job analyses. Figure 6-3 gives a sample job analysis. Note that the job analysis form includes a section in which the evaluating physician is asked to give an opinion about whether the worker can perform the job.

image

FIGURE 6-3 A sample job analysis.

A detailed job analysis can be helpful in the assessment of the work demands that a patient is likely to face. When possible, the examiner should check to see whether the patient agrees with the physical requirements listed in a job analysis. If the patient vigorously disputes the job analysis, the examiner should attempt to reconcile the discrepancy.

Sometimes physicians are presented with “trick” questions dealing with employability. As an example, a physician is treating a patient with chronic low back pain who has failed multiple spine surgeries and continues to complain of relentless pain despite the implantation of an intrathecal opiate delivery system. The physician believes it is unrealistic for this patient to return to competitive employment. A disability agency asks the physician whether the patient can work as a telephone solicitor. This question poses a dilemma. If the physician says “Yes,” the patient’s disability benefits will probably be terminated. If the answer is “No,” the physician is implicitly saying that the low back pain prevents the patient from doing a job that has few physical demands. This can represent an ethical dilemma, and the physician ultimately must use clinical judgment, at the same time addressing guidelines within the disability system.

On the other hand, physicians will encounter some patients who “drag their feet” and overemphasize the severity of their incapacitation. These behaviors should make the physician suspicious of the possibility of a hidden agenda. In such a situation, it is reasonable to stick closely to objective data regarding the patient’s capacities, rather than to be influenced strongly by the patient’s subjective assessments.

Further Special Issues in Disability Evaluations

Possibility of Deception

Physicians need to be aware of the possibility that any of the participants in a disability claim can have a hidden agenda. Opportunities for deception are particularly notable in workers’ compensation claims. An extensive medical literature on secondary gain, compensation neurosis, and malingering has dealt with hidden agendas of patients.5,17,36,40,62

Disability agencies, insurance companies, and defense attorneys at times use video surveillance when malingering or exaggeration of incapacity is suspected. Results can confirm malingering (e.g., a patient with severe “disabling” postlumbar laminectomy syndrome observed hitching a boat to a truck to go fishing for the day). On the other hand, results can corroborate a patient’s loss of function when he or she is blinded to observation (e.g., a patient with a thoracolumbar spinal fusion who shows clear difficulty with routine bending and prolonged weight-bearing activities).

Behavioral signs suggesting psychological distress that can be observed in patients with chronic pain have been inappropriately used within a medicolegal setting as evidence for malingering. The most famous example is the Waddell signs, developed by the well-known spinal surgeon, Dr. Gordon Waddell, who urged his fellow surgeons “to operate on a patient, not a spine,” as this “may save years of coping with the human wreckage caused by ill-considered surgery on the lumbar discs.”63 There have been numerous articles reappraising the Waddell signs, one of which has been coauthored by Dr. Waddell himself,38 making clear that these behavioral signs do not have a role in the detection of malingering.13,16

In summary, most experts in disability believe that frank malingering or deception is uncommon among patients who seem to report “excessive” disability. However, the physician should answer the following questions:

• Is there any evidence that a patient who claims to be disabled is “double dipping,” (i.e., working at the same time he or she is getting disability benefits)?
• Is there evidence from surveillance tapes or other collateral sources that a patient’s physical capabilities are far greater than he or she claims?

Other parties to a workers’ compensation claim, including employers and adjudicators for disability agencies, can also have hidden agendas. Their agendas have been ignored almost completely in research on disability, so the physician needs to use clinical judgment in deciding whether participants in a disability claim are behaving in a deceptive manner. The physician should consider the following:

• Is there evidence that the disability system is unreasonably “playing hardball” with the patient? For example, does it appear that the patient has had his or her claim closed arbitrarily?
• Has the compensation carrier refused to authorize reasonable services requested by the attending physician?
• Does it appear that the patient’s claims manager is requesting multiple evaluations to maneuver the patient out of the compensable claim on the basis of “preponderance of evidence”?
• Is there any indication that the patient’s (former) employer has created misleading job descriptions?
• Has patient’s (former) employer put pressure on the patient not to file a workers’ compensation claim?
• Has patient’s (former) employer fired the patient in apparent response to the patient’s report of injury?

Objective Findings

As noted earlier, the term “objective findings” is not precisely defined.47 Some examiners believe that objective data refer to laboratory or physical findings that are measurable, valid, and reliable and are not subject to voluntary control or manipulation by a patient. Objective findings can be contrasted with “subjective findings” such as patients’ reports of activity restrictions caused by pain. A lot of clinically important examination findings, however, including range of motion (ROM), tested strength, and some muscle stretch reflex findings might be described as “semiobjective.” They are objective in the sense that they can be observed and measured, but they might not be completely reliable because patients can voluntarily modify them. Most adjudicators who request objective findings are not aware of these subtleties. The AMA Guides generally accepts physical examination findings as objective data, even if they are able to be voluntarily manipulated by the patient.

The latest edition of the AMA Guides48 has less emphasis on ROM measurements for determining spinal impairments as compared with prior editions. This has not been done because ROM is subject to voluntary control, but because ROM has not correlated well with loss of function and probable impairment in the spinal region.66

Upper limb ROM determination remains important in the AMA Guides.48 Active ROM is considered to reflect true function better than passive ROM. The AMA Guides also warns that if there is a significant discrepancy between active and passive ROM, however, there should be a clear physiologic basis (e.g., full rotator cuff tear) for the discrepancy. The possibility of symptom magnification and self-inhibition by the patient should be specifically addressed.

As with so many dilemmas in medicine, the physician’s clinical judgment becomes paramount in sorting out “nonorganic” responses from patients during the physical examination. Take the example of a school-age child who does not want to go to school because of abdominal pain. During a medical examination, the physician might take this child in his or her lap and distract the child with something fun to play with, while at the same time palpating the abdomen. If the physician does not get a palpation response consistent with his or her official “physical examination” when the child was not distracted, the physician would take this discrepancy into account when deciding the severity or even the presence of the child’s illness.

When physicians perform a disability evaluation on one of their patients, they can further address the objective findings issue within the assessment and discussion portions of their report. If they do not find the patient credible, they should indicate that there are no reliable objective findings to support the claim of incapacity. However, they should provide documentation to support their opinion. The physician might state, for example, that with the patient distracted, there was no significant tenderness noted in the upper trapezius region, and yet there was a very severe pain response from the patient when he or she was conscious of the physician palpating this region. If the patient has consistent physical findings that the physician finds credible, they can be listed in the space where the physician is requested to give objective findings. If these findings are challenged, the physician can indicate that in his or her clinical judgment, they represent valid indices of the patient’s condition.

Conclusion

This chapter can only point out some of the challenges associated with disability evaluation. It by no means provides all the information needed to conduct disability evaluations of patients. Unfortunately, there is no cookbook for doing disability evaluations. Busy physicians might want a simple answer to the question, “How should I fill out Mr. Smith’s disability form?” In reality, this is akin to asking the question, “What medical or surgical treatment should I provide for Mr. Smith?” In both instances, it is necessary to answer the question based upon factors that are specific to Mr. Smith.

Note that there is strikingly little published information on the subject of disability evaluation, despite the fact that millions of evaluations are done each year in the United States. At a very basic level, there is very little evidence about whether the decisions made by large agencies such as the SSA are overall good or bad—that is, whether the SSA is awarding benefits to individuals who are truly disabled, or is withholding them from individuals who are truly unable to work.45,50,51

In the face of this large-scale uncertainty, it is difficult for individual physicians to know whether they are rendering appropriate judgments regarding their patients. This is particularly the case for disability evaluation in the context of chronic pain, or in other settings where it is difficult to correlate the subjective complaints with objective findings of tissue pathology.

Some will understandably be tempted to ask, “Why bother?” That is, why should a physiatrist take the extra time to learn about disability agencies, disability evaluation methods, the ethics of disability evaluation, etc.? One answer is, “Because physicians have no choice.” Society forces physicians to make judgments about the capacities of their patients. Physicians can perform disability evaluations thoughtfully or thoughtlessly, but they do not have the option of simply not doing them.

Another answer to the “Why bother” question is that disability evaluation is important. In an ideal world, physicians would completely cure all patients. In reality, physicians’ interventions might only partially resolve their patients’ inability to work and function in the community. Consequently physicians have to be concerned about residual impairment and workplace incapacity after treatment has been optimized. Once they have done what they can to help their patients return to economic productivity, physicians need to avoid doing them a disservice by either grossly overstating or understating their capacities to disability adjudicators.

References

1. Alaranta H., Rytokoski U., Rissanen A., et al. Intensive physical and psychosocial training program for patients with chronic low back pain: a controlled clinical trial. Spine. 1994;19:1339-1349.

2. Barnsley L., Lord S., Wallis B., et al. False-positive rates of cervical zygapophysial joint blocks. Clin J Pain. 1993;9:124-130.

3. Barnsley L., Lord S.M., Wallis B.J., et al. The prevalence of chronic cervical zygapophysial joint pain after whiplash. Spine. 1995;20:20-25. discussion 26

4. Beattie P.F., Meyers S.P., Stratford P., et al. Associations between patient report of symptoms and anatomic impairment visible on lumbar magnetic resonance imaging. Spine. 2000;25:819-828.

5. Bellamy R. Compensation neurosis: financial reward for illness as nocebo. Clin Orthop. 1997;336:94-106.

6. Carragee E.J. Validity of self-reported history in patients with acute back or neck pain after motor vehicle accidents. Spine J. 2008;8:311-319.

7. Chibnall J.T., Tait R.C., Andresen E.M., et al. Race and socioeconomic differences in post-settlement outcomes for African American and Caucasian Workers’ Compensation claimants with low back injuries. Pain. 2005;114:462-472.

8. Clark W., Haldeman S. The development of guideline factors for the evaluation of disability in neck and back injuries: Division of Industrial Accidents, State of California. Spine. 1993;18:1736-1745.

9. Clark W.L., Haldeman S., Johnson P., et al. Back impairment and disability determination: another attempt at objective, reliable rating. Spine. 1988;13:332-341.

10. Cocchiarella L., Andersson G.B.J., editors. Guides to the evaluation of permanent impairment, ed 5, Chicago: American Medical Association Press, 2001.

11. Curatolo M., Petersen-Felix S., Arendt-Nielsen L., et al. Central hypersensitivity in chronic pain after whiplash injury. Clin J Pain. 2001;17:306-315.

12. Estlander A.M., Mellin G., Vanharanta H., et al. Effects and follow-up of a multimodal treatment program including intensive physical training for low back pain patients. Scand J Rehabil Med. 1991;23:97-102.

13. Fishbain D.A., Cole B., Cutler R.B., et al. A structured evidence-based review on the meaning of nonorganic physical signs: Waddell signs. Pain Med. 2003;4:141-181.

14. Fishbain D.A., Cutler R.B., Rosomoff H.L., et al. Impact of chronic pain patients’ job perception variables on actual return to work. Clin J Pain. 1997;13:197-206.

15. Fishbain D.A., Cutler R.B., Rosomoff H.L., et al. Prediction of “intent,” “discrepancy with intent,” and “discrepancy with nonintent” for the patient with chronic pain to return to work after treatment at a pain facility. Clin J Pain. 1999;15:141-150.

16. Fishbain D.A., Cutler R.B., Rosomoff H.L., et al. Is there a relationship between nonorganic physical findings (Waddell signs) and secondary gain/malingering? Clin J Pain. 2004;20:399-408.

17. Fishbain D.A., Rosomoff H.L., Cutler R.B., et al. Secondary gain concept: a review of the scientific evidence. Clin J Pain. 1995;11:6-21.

18. Giesecke T., Gracely R.H., Grant M.A., et al. Evidence of augmented central pain processing in idiopathic chronic low back pain. Arthritis Rheum. 2004;50:613-623.

19. Gilovich T. How we know what isn’t so: the fallibility of human reason in everyday life. New York: Free Press; 1991.

20. Gross D.P., Battie M.C. The prognostic value of functional capacity evaluation in patients with chronic low back pain. 2. Sustained recovery. Spine. 2004;29:920-924.

21. Gross D.P., Battie M.C. Does functional capacity evaluation predict recovery in workers’ compensation claimants with upper extremity disorders? Occup Environ Med. 2006;63:404-410.

22. Gross D.P., Battie M.C., Cassidy J.D. The prognostic value of functional capacity evaluation in patients with chronic low back pain. 1. Timely return to work. Spine. 2004;29:914-919.

23. Hazard R.G., Bendix A., Fenwick J.W. Disability exaggeration as a predictor of functional restoration outcomes for patients with chronic low-back pain. Spine. 1991;16:1062-1067.

24. Hidding A., van Santen M., De Klerk E., et al. Comparison between self-report measures and clinical observations of functional disability in ankylosing spondylitis, rheumatoid arthritis and fibromyalgia. J Rheumatol. 1994;21:818-823.

25. Hildebrandt J., Pfingsten M., Saur P., et al. Prediction of success from a multidisciplinary treatment program for chronic low back pain. Spine. 1997;22:990-1001.

26. Holleman W.L., Holleman M.C. School and work release evaluations. JAMA. 1988;260:3629-3634.

27. Ivancic P.C., Ito S., Tominaga Y., et al. Whiplash causes increased laxity of cervical capsular ligament. Clin Biomech (Bristol, Avon). 2008;23:159-165.

28. Jensen M.P., Turner J.A., Romano J.M. Correlates of improvement in multidisciplinary treatment of chronic pain. J Consult Clin Psychol. 1994;62:172-179.

29. Kallakuri S., Singh A., Lu Y., et al. Tensile stretching of cervical facet joint capsule and related axonal changes. Eur Spine J. 2008;17:556-563.

30. Kaplan G.M., Wurtele S.K., Gillis D. Maximal effort during functional capacity evaluations: an examination of psychological factors. Arch Phys Med Rehabil. 1996;77:161-164.

31. King P.M., Tuckwell N., Barrett T.E. A critical review of functional capacity evaluations. Phys Ther. 1998;78:852-866.

32. Koelbaek Johansen M., Graven-Nielsen T., Schou Olesen A., et al. Generalised muscular hyperalgesia in chronic whiplash syndrome. Pain. 1999;83:229-234.

33. Lechner D.E. Functional capacity evaluation. In: King P.M., editor. Sourcebook of occupational rehabilitation. New York: Plenum Press, 1998.

34. Lee K.E., Thinnes J.H., Gokhin D.S., et al. A novel rodent neck pain model of facet-mediated behavioral hypersensitivity: implications for persistent pain and whiplash injury. J Neurosci Methods. 2004;137:151-159.

35. Lipchik G.L., Milles K., Covington E.C. The effects of multidisciplinary pain management treatment on locus of control and pain beliefs in chronic non-terminal pain. Clin J Pain. 1993;9:49-57.

36. Loeser J.D., Henderlite S.E., Conrad D.A. Incentive effects of workers’ compensation benefits: a literature synthesis. Med Care Res Rev. 1995;52:34-59.

37. Lord S.M., Barnsley L., Wallis B.J., et al. Chronic cervical zygapophysial joint pain after whiplash: a placebo-controlled prevalence study [see comments]. Spine. 1996;21:1737-1744. discussion 1744–1745

38. Main C.J., Waddell G. Behavioral responses to examination: a reappraisal of the interpretation of “nonorganic signs.”. Spine. 1998;23:2367-2371.

39. McGorry R.W., Webster B.S., Snook S.H., et al. The relation between pain intensity, disability, and the episodic nature of chronic and recurrent low back pain. Spine. 2000;25:834-841.

40. Mendelson G. Psychiatric aspects of personal injury claims. Springfield: Charles C Thomas; 1988.

41. Osterweis M., Kleinman A., Mechanic D. Pain and disability: clinical, behavioral, and public policy perspectives. Washington, DC: National Academy Press; 1987.

42. Peterson K.W., Babitsky S., Beller T.A., et al. The American Board of Independent Medical Examiners. J Occup Environ Med. 1997;39:509-514.

43. Pransky G.S., Dempsey P.G. Practical aspects of functional capacity evaluations. J Occup Rehabil. 2004;14:217-229.

44. Reville R.T. Institute for Civil Justice (US), California. Commission on Health and Safety and Workers’ Compensation. An evaluation of California’s permanent disability rating system. Santa Monica: RAND Institute for Civil Justice; 2005.

45. Robinson J.P. Evaluation of function and disability. In Loeser J.D., editor: Bonica’s management of pain, ed 3, Philadelphia: Lippincott Williams & Wilkins, 2001.

46. Robinson J.P. Pain and disability. In: Jensen T.S., Wilson P., Rice A., editors. Chronic pain. London: Edward Arnold, 2002.

47. Robinson J.P., Turk D.C., Loeser J.D. Pain, impairment, and disability in the AMA guides. J Law Med Ethics. 2004;32(191):315-326.

48. Rondinelli R.D., editor. Guides to the evaluation of permanent impairment, 6th edn, Chicago: American Medical Association Press, 2008.

49. Rondinelli R.D., Katz R.T. Impairment rating and disability evaluation. Philadelphia: WB Saunders; 2000.

50. Rucker K.S., Metzler H.M. Predicting subsequent employment status of SSA disability applicants with chronic pain. Clin J Pain. 1995;11:22-35.

51. Rucker K.S., Metzler H.M., Kregel J. Standardization of chronic pain assessment: a multiperspective approach. Clin J Pain. 1996;12:94-110.

52. Saal J.S. General principles of diagnostic testing as related to painful lumbar spine disorders: a critical appraisal of current diagnostic techniques. Spine. 2002;27:2538-2545. discussion 2546

53. Schofferman J., Bogduk N., Slosar P. Chronic whiplash and whiplash-associated disorders: an evidence-based approach. J Am Acad Orthop Surg. 2007;15:596-606.

54. Schwarzer A.C., Wang S.C., O’Driscoll D., et al. The ability of computed tomography to identify a painful zygapophysial joint in patients with chronic low back pain. Spine. 1995;20:907-912.

55. Shamji M.F., Allen K.D., So S., et al. Gait abnormalities and inflammatory cytokines in an autologous nucleus pulposus model of radiculopathy. Spine. 2009;34:648-654.

56. SSA. Disability evaluation under social security. Washington, DC: US Government Printing Office; 1994.

57. Sterling M., Jull G., Vicenzino B., et al. Sensory hypersensitivity occurs soon after whiplash injury and is associated with poor recovery. Pain. 2003;104:509-517.

58. Sullivan M.D., Loeser J.D. The diagnosis of disability. Treating and rating disability in a pain clinic. Arch Intern Med. 1992;152:1829-1835.

59. U.S. Department of Labor, Bureau of Labor Statistics. U.S. Nonfatal occupational injuries and illnesses requiring days away from work for State government and local government workers, 2008. Available at: http://www.bls.gov/iif/oshcdnew.htm. Accessed January 21, 2008.

60. VA. Federal benefits for veterans and dependents. Washington, DC: Superintendent of Documents; 2007. US Government Printing Office

61. van Tulder M., Koes B., Bombardier C. Low back pain. Best Pract Res Clin Rheumatol. 2002;16:761-775.

62. Voiss D.V. Occupational injury. Fact, fantasy, or fraud? Neurol Clin. 1995;13:431-446.

63. Waddell G., McCulloch J.A., Kummel E., et al. Nonorganic physical signs in low-back pain. Spine. 1980;5:117-125.

64. Yamashita M., Ohtori S., Koshi T., et al. Tumor necrosis factor-alpha in the nucleus pulposus mediates radicular pain, but not increase of inflammatory peptide, associated with nerve damage in mice. Spine. 2008;33:1836-1842.

65. Ziporyn T. Disability evaluation: a fledgling science? JAMA. 1983;250:873-874. 879-880

66. Zuberbier O.A., Kozlowski A.J., Hunt D.G., et al. Analysis of the convergent and discriminant validity of published lumbar flexion, extension, and lateral flexion scores. Spine. 2001;26:E472-478.

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