Disability and chronic pain commonly co-occur, particularly in the case of diagnoses with controversial etiologies. When disability impacts work, the contributory factors become even more complex, with occupational disability bearing scant relationship to a patient’s specific clinical state. Given the weak relationship between medical diagnosis, clinical severity, and work disability, investigators have championed the decade of “yellow flags,” outlining a series of proposed predictors of work disability, including psychosocial, economic, and environmental factors. Identification of these factors in the individual patient can assist the clinician in achieving a better outcome. Conversely, failure to adequately assess can contribute to unnecessary or inappropriate treatment and chronic disability.

Recent studies note that about 17% of people in the United States have a disability, or 54 million American people.¹ Notwithstanding measurement difficulties, studies consistently reveal that people with disabilities are less likely to be employed than people without disabilities (21% vs. 59%), are more likely to live in poverty (34% vs. 15% as defined by less than $15,000 annually), are more likely to not have graduated high school (17% vs. 11%), and are more likely to have a significantly lower quality of life (34% vs. 61%).² The problem is worldwide, although estimates across countries vary widely, largely because of the variability in the operational definition of disability. In addition, social factors and practice patterns of health care providers result in response bias.

Even within a given state, work disability rates may show considerable variability over time based on economic conditions or local laws that reinforce changes in behavior. State law may eliminate benefits after a specified time, resulting in dramatically increased work return rates. Some states restrict access to subspecialists, another factor that may directly impact work disability.³ The U.S. Federal Social Security Disability Insurance (SSDI) program reported return-to-work rates that hovered at less than 1% for 25 years, with more recent changes resulting in financial incentives that encourage a return to part-time employment. In many cases, a patient’s disability may have little relationship to diagnosis or any “objective” measure of physical impairment.

Many studies report higher rates of physical disability in underdeveloped countries, particularly when more objective measurements are used.⁴ Not surprisingly, many individuals may work despite physical disabilities or pain, particularly if the government fails to provide a financial safety net. Conversely, the percentage of people who report chronic pain is significantly lower in developing countries (2.9%); the United States has a rate of 15.5%.⁵ Patients in developed countries may also expect that they should not or cannot work with chronic pain conditions, a belief system often shared by treating physicians.⁶ Chronic pain remains one of the leading factors contributing to disability in the United States, regardless of diagnosis or physical impairment.^5,7–12

Clinicians who care for patients with chronic pain are often fully aware of the high rates of disability. Lacking knowledge, tools, or an incentive to address work disability, some may simply ignore the issue and instead focus on what they know best: treatment approaches that narrowly target impairment, nociception, or some underlying pathological etiology. If frustrating questions arise with respect to the patient’s functional status or return-to-work goals, they are commonly ignored. In other cases, return-to-work issues may be addressed by asking the patient to return to his or her primary care physician “because our office doesn’t do disability forms.” When psychological factors are readily apparent, a referral may be made to a mental health clinician. A general mental health practitioner would typically address immediate psychiatric comorbidities, often ignoring or failing to understand risk factors associated with chronic work disability.

This vacuum of care with respect to return-to-work assessment is often filled with commercial disability assessment specialists, a field populated by independent medical examination and functional and work capacity experts. These “independent” physicians often work in concert with insurance carriers or government-funded assessment panels, relationships that may not always favor the patient. In this setting, the patient’s disability is typically addressed from a medical standpoint, with a preference for “objective” medicolegal measures of impairment. There often is an expectation that the evaluation results would provide an objective basis for compensation. Failure to find and identify sufficient underlying physical pathology, as in the case with many chronic pain patients, may result in conclusions about “symptom magnification” or even malingering. Despite lack of validity, there are examples in which Waddell signs or functional capacity assessments are used to assess the patient’s credibility, with the authors of these tests decrying such uses.^13,14 All of the above approaches typically ignore the body of evidence that underscores the complexity of the work-related factors, often to the peril of the patient.

The role of pain physicians in work-related disability cases is widely debated, and failure to understand the ramifications of the physician’s responsibilities may greatly compromise the patient’s status.¹⁵ Kosny and his colleagues^7,16 found that practitioners unwittingly play a “key role in complicating and prolonging compensation claims”(p. 583).¹⁷ This is in part due to limited understanding of the compensation system and requirements, as well as confusion about decision making with respect to patient care. The results of a study by Lotters et al.^8,18 are even more damning, with the authors concluding that regardless of the severity of the pain disorder, merely visiting a subspecialist was associated with a failure to fully return to work. Although the claim that physicians may promote disability is nothing new, the tendency to disable our patients may go largely unrecognized even by the most diligent and empathic clinician.

Despite these findings, there are some bright spots. Dasinger and his colleagues^9,19 found that the direct advice from a physician to return to work was associated with a 34% decrease in disability benefit status compared with patients who were not encouraged by physicians to return to work. Other investigations suggest that choice of active interventions by the clinician, such as self-directed exercise, may significantly improve return-to-work rates over the selection of passive treatments, such as massage or aquatherapy.^10,20 Underscoring the importance of active approaches in management of chronic pain and disability, others report that a return to “full active duty” may be better than suggesting “light duty.” The limited “light duty” responsibilities may perpetuate an image of an underperforming disabled worker and contribute to the development of a worker sick role at the work site.¹¹

Disability is a complex concept that is continually being redefined. The definition differs greatly based on who, what, where, and why one is asking. The social and medical models are often seen in conflict, with the medical model of disability closely related to the construct of “impairment.”¹⁶ Impairment is a loss or abnormality of body structure or of a physiological or psychological function, such as a loss of a limb or a loss of vision. Because of its narrow focus, impairment can be more objectively defined and reliably measured. In contrast, the construct of disability typically refers to an inability to carry out necessary tasks in any important domain of life because of a medical (or psychiatric) condition.¹⁷ The American Medical Association (AMA) defines disability as “an alteration of an individual’s capacity to meet personal, social, or occupational demands or statutory or regulatory requirements because of an impairment”¹⁷ (p. 2). Those espousing a social model seek to further broaden this definition, with reasonable support from empirical studies. Combining both the social and medical aspects of disability but keeping the construct of impairment, the United Nations Convention on the Rights of People with Disabilities (CPD) offered the following: “Persons with disabilities include those who have long-term physical, mental, intellectual or sensory impairments which in interaction with various barriers may hinder their full and effective participation in society on an equal basis with others.”¹⁸ Although 101 of 149 countries from the United Nations have ratified this text of the CPD as of 2011, controversies persist with respect to operational definitions and strategies for assessing disability. Some academics and leaders in the disability rights movement who advocate exclusive use of a social model have taken the position in the extreme, affirming, “The body has nothing to do with disability.”¹⁹

There are various strategies for classifying psychological factors that impact on disability. Nicholas and his colleagues²¹ proposed a five-color nomenclature that uses warning “flags,” each with a different type of risk factor (Table 25-1). Most factors overlap, and a patient may easily fall into several categories. No single psychological factor controls most of the variance in predicting to work disability, and there are conflicting data for some. However, all appear to be better predictors than more “objective” physical parameters. Most of the work has been conducted with chronic low back pain populations, but other persistent pain populations have been widely studied. These include neck pain, chronic headache, fibromyalgia, complex regional syndrome, and various other persistent myofascial and neuropathic pain syndromes.^22–27

It is unremarkable that patients with chronic pain and severe psychiatric factors tend to have problems with work-related disability, in contrast to patients who have fewer psychiatric comorbidities. The typical predictive comorbid psychiatric disorders include depression, anxiety (including posttraumatic stress disorder [PTSD]), somatoform disorders, and substance use disorders. Not surprisingly, the presence of severe psychopathology not only predicts to work disability but also various adverse health outcomes, poor medical adherence, and a poor response to many types of treatment.^28,29 They are often missed by the physician or minimized by the patient during initial assessment, partly because of the singular focus on the pain complaints.

Bair and colleagues³⁰ addressed the relationships among anxiety, depression, pain intensity, pain-related disability, and quality of life. They replicated the work of numerous other investigators who demonstrated the relationship between depression and anxiety in patients with chronic pain and its association to increased levels of disability. As expected, depression and anxiety also predicted to overall poorer health-related quality of life.^31,32 The impact also appears to have a lasting effect. Brage and his associates found that severe emotional distress was a predictor of work disability in a 12-year follow-up study of patients with low back pain.³³ It can be argued that low levels of distress or dissatisfaction with disability may motivate the patient to improve function and return to work, although more severe psychiatric symptoms may be a different matter. Again, adequate patient assessment and treatment may help, including efforts to provide the patient with avenues for rapid return to employment.

Although active substance abuse has been shown to be a predictor of work disability through decades of research, patients with chronic pain may even have a greater risk. Substance abuse disorders in the general population range from 3% to 16%,³⁴ and substance abusers are two to six times more likely to appear in chronic pain populations.³⁵ Issues of iatrogenic addiction also can occur with chronic opioid therapies.³⁶ Although screening for addiction is often considered a minimum standard of care for all medical patients, the need is particularly relevant with chronic pain populations. Most attention to substance abuse occurs within the context of risk stratification for opioid therapy, with the opportunity for substance abuse screening being missed with the majority of the other patients.

Somatoform disorders, particularly somatization disorder, are often overlooked when addressing work-related disability. In part, the patient meeting criteria for this disorder may obtain a more palatable multiple co-occurring medical diagnosis such as fibromyalgia, diffuse myofascial pain, chronic headache, and so on. Commonly missed by mental health clinicians and subspecialists, patients with somatoform disorders usually present with chronic pain conditions as a component of their full set of symptoms, seek out multiple physicians, and experience long-standing work disability. Fear avoidance of activity is common, with many patients developing iatrogenic complications from multiple surgical, interventional, or pharmacologic approaches aimed at treating their supposed underlying disease.¹² Patients commonly underestimate their ability to function. Barsky et al. (2005)³⁷ estimate that $256 billion is spent per year on medical care costs attributable to the incremental effects of somatization alone.³⁷ Many of these patients report disablement in all areas of functioning and often seek out work disability. As with the other psychiatric conditions, overlay with anxiety and affective disorders is quite common. For patients with marked oversomatization, the best practice includes avoiding unnecessary subspecialists and coordinating through primary care. Although some data support interdisciplinary pain care and cognitive therapy as adjunctive approaches, studies are few.³⁷ In most cases, the patient benefits from the focus and distraction of employment, and time off for symptoms should be avoided.

Although fibromyalgia has been accepted as a medical disorder and there appears to be a growing body of research suggesting biological markers, the overlap with psychiatric disorders remains significant. Patients with fibromyalgia have a prevalence rate of 20% for PTSD.³⁸ Similarly, back pain, headaches, pelvic pain, chronic abdominal pain, irritable bowel syndrome, and temporomandibular joint disorder have been correlated with psychological trauma, and each one commonly co-occurs with fibromyalgia.³⁹ All have been shown to contribute to work disability. Indeed, many argue that these are “spectrum disorders” closely overlapping in etiology. In each case, evidence-based treatment recommendations include reinforcement of activity, cognitive therapy approaches, and early return to work when possible.

Consistent with many diffuse chronic pain diagnoses, the number of pain sites appears to be a significant factor that impacts disability. In contrast, the severity, intensity, and frequency of pain do not appear directly related to the level of work disability.⁴⁰ A prospective study conducted over 14 years demonstrated that 80% of the variance in disability related to chronic pain was accounted for by the number of pain sites.⁴¹ Again, these are likely to be patients with diffuse pain diagnoses as noted earlier. Each subspecialist may chase the patient’s changing symptoms with new diagnostics and peripheral treatments and perhaps forget that the patient is at great risk for chronic work disability. Being aware of patients who present with multiple pain sites may give the practitioner an opportunity to intervene early and identify sources for return to work.

Cognitive constructs or belief factors with chronic pain are some of the most studied psychological factors related to a person’s functioning, quality of life, and work-related disability. These include the constructs of “acceptance,” “catastrophizing,” “fear avoidance,” “pain perception,” “disease or disability conviction,” and “self-efficacy.” Each has been shown to be predictive to general disability measures and work disability in particular.

McCracken and his colleagues⁴² found that acceptance of pain predicted better adjustment on all measures of pain function independent of pain intensity.⁴³ Thus, a person’s ability to adapt to new (and often stressful) situations is a relevant factor in the response to treatment. Acceptance has often been misunderstood as satisfaction with a situation, which may not be the case. Hence, a patient with pain may not be happy or even satisfied with a situation, but he or she can still “accept” the facts of the moment and respond to the situation effectively.⁴⁴ Examples of positive acceptance might include statements such as “I know the pain sometimes will get worse, but I won’t injure myself if I work, or if I walk to the store.”

Relating to the construct of acceptance, Gross et al.⁶ found that those who believed that a reduction in pain is necessary for resumption in functioning showed a greater likelihood of obtaining disability claims. Patients who took the most time off from work were most likely to agree with the premise that if you have back pain, you should rest until it gets better. Rather than “accept” the typical variability in pain level common with chronic pain conditions, the work-disabled patient may wait until the clinician offers a “fix” or “a cure” or at least “gets better” in terms of pain level. Unfortunately, the pain returns, often unrelated to work activity, and the patient becomes fearful of injury, withdrawing again from work.

Casey and colleagues²⁷ found that there were several factors related to the formation of chronic pain and disability after an acute back injury, with the most predictive factor being negative pain beliefs. Patients who felt that pain would be permanent had higher rates of disability at a 3-month follow up. Other studies have demonstrated that results consistent with these findings, (e.g., “learned helplessness” and pessimistic views about the future) predict higher levels of work disability.^45,46

Fear avoidance and catastrophizing have also been shown to be strong predictors of disability and work status. In particular, fear avoidance describes a person’s beliefs that certain physical activities are more harmful and would end up causing more pain. Prior studies have evaluated the effect of fear avoidance in patients with low back pain and found that fear-avoidant beliefs predict both disability status and work status after 1 month.⁴⁷ This appeared to be the case despite level of pain and level of “objective” impairment. Although other reviews on fear avoidance are mixed with respect to the amount of impact on return to work, fear avoidance remains an important component of chronic disability behavior.⁴⁸

Similar to many of the dysfunctional cognitions discussed, fear avoidance and catastrophizing are interrelated constructs. Catastrophizing can be thought of as an exaggerated and overly negative perception of pain, worry related to injury, or related belief.²² Negative thoughts about work activity are reinforced as activity is avoided, and the patient feels transiently better with a reduction in anxiety after terminating work. The cycle continues, leading to increased disability and further fear-avoidance behaviors, culminating in more extensive catastrophizing thoughts, actions, and behaviors. Buer and Linton²² compared patients with back pain with the general population, finding that fear avoidance and catastrophizing were related to reduced activities of daily living and reports of pain among patients with persistent pain. Although both cognitions were present in the general population during the beginning stages of pain, these negative thoughts did not persist with the nonpain patients.

Although fear avoidance and catastrophizing are interrelated, there may be differences with respect to predicting longer term work disability. In a prospective study of 202 patients with pain, Wideman and Sullivan found that whereas catastrophizing was most related to long-term pain intensity, fear was most related to long-term work disability.^48,49 In either case, the pain clinician may query the patient with respect to specific fears and worries about activities, fears related to return to work, or other barriers that might be preventing success. Although it is common to assess the patient’s objective behaviors with respect to work activities such as lifting and carrying, we often fail to assess the patient’s fears about these activities and their perceived consequences.