Diagnostic judgment: Chronic pain syndrome, pain disorder, and malingering

Two decades of research have made it clear that physicians must distinguish pain from physical impairment, and differentiate illness behavior from disability. Also important is the distinction between disability and physical impairment as a consequence of physical pathology. The contribution of psychological, social, and behavioral factors to disability ranges from minimal to major.

While delayed recovery can be a consequence of failure to detect physical pathology or psychiatric disorders, a subgroup of patients demonstrate illness behavior in the absence of detectable underlying physical or psychiatric impairment and demonstrate non-organic (medically incongruent) signs.[1,2] Environmental contingencies are responsible for their illness behavior. Direct reinforcement of pain behaviors occurs when they are followed by positive consequences. Indirect reinforcement occurs when pain behaviors lead to avoidance or reduction of unpleasant events. Chronic pain syndrome and pain disorder are diagnostic labels frequently applied to patients who are thought to be demonstrating delayed recovery as a consequence of social reinforcement.

Chronic pain syndrome

The chronic pain syndrome construct was delineated in 1987 when it was argued that chronic pain syndrome, as opposed to chronic pain, “has the added component of certain recognizable psychological and socioeconomic influences.”[3] The presence of at least four of the following eight characteristics was said, by the American Medical Association (AMA), to establish the diagnosis of chronic pain syndrome:[4]

• Duration
• Dramatization
• Drugs
• Despair
• Disuse
• Dysfunction
• Diagnostic dilemma
• Dependence on others and/or on passive physical therapy

The AMA stated that chronic pain syndrome has its origin in both iatrogenic factors, such as prolonged use of passive physiotherapy modalities and prolonged inactivation, and nomogenic factors (nomogenesis refers to abnormal illness behavior functionally related to social legislation that rewards complaints of pain, suffering, and disability; that is, to the anticipation of financial gain).

It was initially assumed that psychological factors would require some time to have an impact following an acute injury, possibly due to avoidance learning leading to disuse, a concept now challenged. For example, in a longitudinal evaluation of the recovery of 117 individuals from an acute back pain episode, “there was no evidence of chronic pain evolving and growing, but rather of a persistence of the acute presentation.”[5] Patients involved in litigation showed the presence of chronic pain reactions within 8 days of pain onset. Forty-eight percent had contacted lawyers. “Those already in touch with a lawyer or planning litigation reported significantly more daily disruption in household chores and had significantly higher reports of pain impact, despite comparable reports of pain to those not engaged in litigation.”[5] Additionally, they demonstrated inconsistencies in self-report concerning disability. There was a significant association between litigious involvement and chronic pain complaints at 6 months. It was also observed that chronic pain behaviors may be noted very early after low back injury, and can accurately predict delay in return to work.[6] Using the Vermont Disability Prediction Questionnaire administered to workers within 15 days of their injury, it was possible to predict 3-month post-injury work status with 94% sensitivity and 84% specificity.[7]

Pain disorder

Although the AMA clearly stated that chronic pain syndrome does not constitute a psychiatric disorder,[8] the diagnosis is often equated with the psychiatric diagnosis of pain disorder associated with psychological factors.[9] This Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) diagnosis is of little value to the disability examiner, since the diagnostic criteria require that all other diagnoses, including malingering, be ruled out.[6] Additionally, not all patients with intractable pain have a mental disorder.[10] Indeed, pain can be understood as learned behavior. “Here the salient aspect of intractable pain is not the disturbing mental experience but, rather, the activities and behaviors that accompany it, such as grimacing, complaining, lying down, taking analgesics, and staying away from work. Such behaviors were first learned when the pain began, but they persist after the original cause of the pain has ceased, continuing as long as the positive and negative reinforcements do. In operant conditioning, pain behaviors are reinforced when rewarded and inhibited when ignored, discouraged, or punished. For example, pain symptoms may become more intense, more frequent, and more disabling when followed by the solicitous and attentive behavior of others, the pleasurable effects of narcotic analgesics, the monetary gains of litigation or disability compensation, and the successful avoidance of distasteful activities. Families can thus reinforce chronic pain by rewarding pain-related behaviors.”[10]

Disability can become a conditioned response, allowing one to “avoid undesirable activities, maintain self-esteem (by displacing the responsibility for failure to perform on the impairment), exert control over others, gain special considerations, or satisfy socially unacceptable needs (e.g., extreme dependency).”[11] Of course, one must recognize the miserable consequences of illness behavior, including loss of employment, changed family status, loss of personal control, less satisfying social engagements, and forced contact with disability officials and health practitioners. In the delayed recovery situation, when operant explanations are warranted, it would appear that the gratifying outcomes of illness behavior outweigh the miserable ones.

Forensic decision-making

The American Psychiatric Association’s DSM-IV-TR[9] states that classification of mental disorders was developed for use in clinical, educational, and research settings. These diagnostic criteria have not been validated for use in forensic settings. Assignment of a particular diagnosis “does not imply a specific level of impairment or disability” or “carry any necessary implication regarding the individual’s degree of control over the behaviors that may be associated with the disorder.”[9] It is also noted that inclusion of a disorder in the manual does not require that there be knowledge about its etiology. Thus, categorization would be of little value for legal judgments concerned with issues of individual responsibility or disability determination, and where the subject’s agenda is far removed from clinical, educational, or research matters.

Psychological investigations, in cases of compensable injury, seek to explain why a particular individual reacted in a particular way to a particular event. “Reliance on a diagnosis to achieve this objective and describe functional capacity is wholly inadequate and explicative of nothing. The expert examiner must provide reliable explanatory data, must articulate not only to what degree the claimant has been effected (disability) but how (injury) and why (causation). Experts who base the finding of disability solely on a diagnosis should be challenged… on the grounds of relevance and insufficient foundation.”[12]

Evidentiary basis for diagnostic judgments

Disability determination is vulnerable to multiple sources of distortion and bias, since the examiner must rely heavily on an individual’s self-report, which is influenced by factors such as social reinforcement, expectations, and environmental contingencies.[13] Significant discrepancies between self-report and observed behaviors have been found for variables such as activity levels, social interaction, and medication use. Patients frequently and significantly under-report their involvement in physical and social activities. Nonverbal behavior can also be a source of error.[14]

Disability compensation is associated most consistently with distortions in self-reported pain, depression, and disability, both before and after rehabilitation has been instituted.[15,16] A subgroup of patients who are receiving or anticipating financial compensation also tend to demonstrate a greater incidence of nonorganic signs on physical evaluations and inconsistencies in self-report on psychometric testing.[17] If not aware of these potential errors, an examiner could easily contribute to the claims build-up.

Malingering

The DSM-IV-TR defines malingering as the “intentional production of false or grossly exaggerated physical or psychological symptoms, motivated by external incentives such as avoiding military duty, avoiding work, obtaining financial compensation, evading criminal prosecution, or obtaining drugs.”[9] The major problem is often not so much recognizing incentives to exaggerate or falsify symptoms as it is identifying purposeful misrepresentation. There is a paucity of research on the detection of malingering and an absence of research demonstrating that psychiatrists or psychologists are able to detect malingering on the basis of clinical interview.[18,19]

Social reinforcement of pain/disability behaviors

The following assessment findings signal social reinforcement as a major factor in maintaining an individual’s complaints of pain and disability:[9,17,20-30]

• Presentation of oneself as severely disabled in the absence of objective findings of physical impairment to substantiate complaints.
• Nonorganic signs on physical evaluations.
• Inconsistencies in self-report.
• Highly elevated or atypical pattern of psychometric test results.
• Extremely elevated scores on scales one and three of the Minnesota Multiphasic Personality Inventory-2.
• Behavioral observations during clinical interview that are discrepant from an individual’s self-report.
• Report of little, if any, improvement, despite intervention that is typically effective.

No finding should be interpreted in isolation. A conclusion that social reinforcement factors are the most important determinants of pain and disability behaviors should be based on multiple objective findings. Moreover, alternative explanations for these findings must be considered.[31] For example, inconsistencies in self-report can reflect factors such as limited cognitive capabilities, carelessness, fatigue, or the effects of drugs or alcohol.

Predictors of delayed recovery

Epidemiological studies have revealed that the following psychosocioeconomic factors place an individual at high risk for reporting delayed recovery subsequent to trauma: previous history of compensable injuries and occupational disability, history of psychiatric problems, substance abuse, recent psychosocial stressors, presence of disability benefits, unresolved litigation, job dissatisfaction, history of poor work performance. Life and work difficulties predicted whether employees would subsequently be off work because of back pain,[32] as did Minnesota Multiphasic Personality Inventory-2 scale three scores and the level of enjoyment of work tasks.[33]

Summary

“If, indeed, we are advocates of patients and society, we should encourage rehabilitation, not disability… Often, it is far easier to write a letter supporting a patient’s claim for disability than it is to explain why the patient could be working and is not… As difficult as it may be, we must, with understanding and compassion, objectively assess impairment and not confuse our role as the patient’s advocate with our responsibility for objectivity. Perhaps it should be an independent physician, rather than the treating physician, who can most objectively, accurately, and unemotionally rate impairment, thus maintaining the uniqueness of the treating physician/patient relationship.[34] In many cases of delayed recovery, interdisciplinary assessment is warranted. In all cases, early intervention is essential.

Competing interests

Dr Hayes has worked as a consultant for ICBC and the BC Interdisciplinary Pain Assessment Clinic providing psychological assessments of individuals with chronic pain problems and outstanding litigious issues.

Bonnie J. Hayes, PhD, Kenneth D. Craig, PhD, Peter C. Wing, MB, ChB, FRCSC

Dr Hayes is a psychologist, formerly with the BC Interdisciplinary Pain Assessment Clinic in Vancouver BC. Dr Craig is a professor of psychology at UBC and an expert in pain disorders. Dr Wing is a clinical professor of orthopedics at UBC.