Research Review By Dr. Demetry Assimakopoulos©

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Date Posted:

June 2020

Study Title:

You’d Better Believe it: The Conceptual and Practical Challenges of Assessing Malingering in Patients with Chronic Pain

Authors:

Tuck NL, Johnson MH & Bean DJ

Author's Affiliations:

Auckland Regional Pain Service (TARPS), New Zealand; Department of Psychological Medicine, University of Auckland, New Zealand

Publication Information:

Journal of Pain 2019; 20(2): 133-145.

Background Information:

Chronic Pain (CP) is an incredibly costly condition that affects approximately 20-40% of the adult population (1-3). In many cases, the diagnosis of chronic pain and resultant disability cannot be objectively measured and is based almost entirely on subjective patient reporting. Because of the inherent subjectivity of the pain experience, patients are often suspected to be malingering, or intentionally exaggerating symptoms for personal gain.

The DSM-V (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) defines malingering as “the intentional production of false or grossly exaggerated physical or psychological problems, motivated by external incentives such as financial compensation, military leave, or medications.” It is important to note that the DSM does not classify malingering as a psychiatric disease, but as a potential focus of clinical attention. The DSM further states that malingering can be suspected when there a combination of: 1) a medicolegal context; 2) a discrepancy between self-report and objective findings; 3) poor cooperation in assessment and treatment; and 4) when antisocial personality disorder is present. The estimated prevalence of malingering in chronic pain cases in the context of financial incentives is as high as 20-50% (4-6)!

There are currently 4 methods of identifying intentional exaggeration of symptoms, including behavioural signs, functional capacity evaluations (FCE’s) to assess effort bias, pen and paper questionnaires and symptom validity tests. With this being said, identifying malingering in the context of chronic pain is complex. These complexities will be discussed in this Review.

Summary:

There are multiple challenges to clinically identifying malingering. Firstly, nociceptive amplification at the level of the CNS represents part of the physiologic basis for chronic pain, in the form of central sensitization. With this being said, chronic pain patients may have very little evidence of overt biomedical pathology, but still endorse high amounts of pain and disability due to these established neurophysiological processes.

Secondly, chronic pain patients may describe non-specific symptoms such as fatigue, bowel/bladder symptoms, sleep problems, headache, pelvic pain, depression and anxiety, which are known predictors of increased pain severity and disability.

Patients may also suffer from alternative psychiatric or neurologic conditions, such as somatic symptom disorder (AKA SSD; previously known as somatoform disorders), factitious disorder, illness anxiety disorder (previously known as hypochondriasis) and functional neurological disorders (previously known as Conversion disorder). Malingering is set apart from these diagnoses by both the degree of intent and/or the specific motivation. By definition, malingerers deceptively, consciously and intentionally feign symptoms for some form of gain.

In contrast, the symptoms and signs featured in the alternative psychiatric or neurologic conditions stated above are mostly unconscious and non-deliberate. Specifically, Somatoform disorder (SSD) refers to the unintentional manifestation of psychological distress via the presentation of (real) bodily symptoms. Factitious disorder is considered when a person fabricates symptoms owing to an (unintentional) need to assume the sick role (primary gain). Illness anxiety (hypochondriasis) is identified when a person is preoccupied with having or acquiring a serious illness in the absence of somatic symptoms or when symptoms are mild. Finally, functional neurologic disorder (Conversion disorder) relates to unintentional alterations in voluntary motor or sensory function that are incompatible with recognized neurologic or medical conditions. A more fulsome outline of the diagnostic criteria for the above-mentioned DSM-5 diagnostic conditions is above is beyond the scope of this review.

Possible clinical methods for detecting malingered pain across five primary domains of enquiry are described below.

1) Behavioural Signs:

Pain behaviour refers to observable behaviours that are shaped by operant reinforcement, including verbal (vocal complaints, moaning, sighing) and nonverbal (bracing, guarding, rubbing, grimacing, posture, assistive devices) cues. These may provide useful information about the patient’s mental and physical state and have formed the basis of malingering detection. Although these behaviours may be genuine, they can also be the product of other reinforcement contingencies and may not be deliberate or deceitful. The most commonly cited behavioural signs are Waddell Signs, and are described below.

Waddell Signs and Other Behavioural Signs:
  • Waddell signs include specific patterns of tenderness, pain with simulation testing, changes in behaviour when distracted, regional disturbances inconsistent with known neuroanatomy, and overreaction. Observed behaviours that are considered exaggerated or inconsistent with known pathology are thought to indicate deliberate feigning.
  • Contrary to this belief, observed behaviours are informed by social and cultural factors, and develop over a lifespan. Inconsistencies are to be expected, given pain fluctuations and the variable influence from biological, psychological and social factors. Simply put, there is no way to know if pain behaviours are deliberate or the result of learning. Certain symptom patterns (i.e. superficial skin tenderness) are also now established features of central sensitization and other neuroplastic mechanisms (i.e. allodynia), which are discussed further below.
2) Effort Bias:

Strength testing is one method that has been created to identify malingered pain. Specifically, functional capacity evaluations (FCE’s) are tests of physical strength that are designed to determine a patient’s level of disability and plan treatment. They require the patient to exert maximal effort during examination to accurately represent their capabilities. A less than maximal effort is termed insincere effort or an effort bias. Those who provide insincere effort are believed to be malingering.

During assessment, strength can be tested using 5-position grip strength dynamometry. It is believed that patients providing maximum effort should produce a bell-shaped curve throughout these positions, while those who provide less than maximal effort produce a flattened force curve, thus indicating deliberate deception.

However, there are many reasons, apart from deliberately feigning, why a person in pain may exert less than maximum effort in strength testing. These reasons include (but are not limited to) fear of pain or reinjury and pain inhibition. There is no way to know if the patient is consciously feigning, and as such, there is little support for the use of strength/effort testing to identify malingered pain. Clinical studies in this regard also have typically utilized simulated models of malingered pain, which is poorly generalizable.

3) Pen and Paper Questionnaires:

It has been proposed that specific responses on questionnaires may suggest deliberate exaggeration of symptoms. The most commonly used questionnaires are the Multiphasic Personality Inventory (a subscale of the Minnesota Multiphasic Personality Inventory [7]) and the Modified Somatic Perceptions Questionnaire.

Unfortunately, these types of questionnaires have poor psychometric properties and may not have been successfully validated in people with chronic pain. Additionally, there are no ‘known groups’ of pain malingerers to generate valid cut-off scores for these self-report measures. Furthermore, clinicians should be aware that many chronic pain patients describe non-specific symptoms, which may be explained in part by neuroplastic changes and psychological factors, and not by deliberate feigning. Labelling distressed patients as malingerers also contravenes the biopsychosocial model of pain.

4) Neurocognitive Assessments/Symptom Validity Tests (SVTs):

Malingering has been most studied in the context of medicolegal neurocognitive assessment, through the use of symptom validity testing (SVT). SVTs are designed to identify intentional poor performance. SVTs generally follow a protocol in which the patient is presented with a stimulus and is then instructed to identify the original stimulus from a series of options. For example, the patient may be presented with a 5-digit number, and then be instructed to identify that number from other series of numbers. It is assumed that the patient will respond correctly 50% of the time by chance alone. If the patient scores below 50% accuracy, they are purported to be deliberately attempting to respond incorrectly and are thus malingering (8). The most widely used SVTs are the Test of Memory Malingering, the Word Memory Test and Portland Digit Recognition test.

Studies have shown that these tests may reliably detect exaggeration of cognitive deficits in chronic pain samples, particularly in the context of litigation. However, while SVTs may be useful for identifying malingered cognitive dysfunction, their ability to detect malingered pain/disability remains unproven. SVTs are also very time consuming, and multiple tests/instruments are required to ensure reliable testing.

5) Combined Methods to Detect Malingering:

It has been proposed by some that malingered pain can be identified by combining multiple approaches (9). Proposed criteria include a combination of: 1) evidence of significant external incentive; 2) evidence from physical examination (i.e. effort bias or Waddell’s signs); 3) evidence from neurocognitive testing (below chance performance on SVTs); 4) evidence from self-report measures; and 5) behavioural responses likely representing a volitional act to obtain secondary gain that are not accounted for by another condition (9). Unfortunately, these criteria are not sufficiently validated in samples of people with chronic pain. Additionally, much like arguments posed previously, displayed symptoms and signs can be unconscious and/or exist as a manifestation of spinal and supraspinal neuroplastic changes, such as central sensitization and related phenomena.

An Alternative View: Malingering in the Context of Pain Science

The biopsychosocial (BPS) framework conceptualizes pain as a subjective multifactorial phenomenon, characterized by symptoms and distress, rather than tissue injury (10). As such, the authors argue that concluding a patient is malingering based on existence of excessive pain, pain behaviours, distress and disability is at odds with this BPS framework. While the BPS framework has been the dominant model of pain for some time, the application and integration of this approach has been slow, exemplified by continued efforts to detect malingered pain.

Numerous advances in the understanding of central neurophysiological mechanisms underpinning pain amplification have taken place over the last three decades. These discoveries enable clinicians, scientists and patients alike to accept that the experience and reporting of pain may be higher than expected compared to the degree of observed tissue damage. Similarly, it is now widely accepted that psychological and emotional factors such as depression, anxiety, expectation, fear-avoidance, self-efficacy, catastrophic thinking, and operant and classical conditioning are predictors of pain severity and disability. These affective, motivational and cognitive factors interact with and contribute to neurophysiologic mechanisms underpinning pain. As a result of these discoveries, the phenomena that have formed the basis for malingering assessment tools can now be explained via various neurophysiological processes.

Clinical Application & Conclusions:

Although it is true that people can and do malinger pain symptoms, it remains extremely difficult to detect malingering without (covert) surveillance. These authors question the usefulness of any of the proposed methods used to clinically identify malingering, as the experience of pain is formed by various biopsychosocial contributors. The authors additionally state that the assessment of malingering is inconsistent with the advancement of pain science because many of the proposed features of malingering can be explained by phenomena such as central sensitization and fear-avoidance behaviour.

They recommend that clinicians, researchers and funding bodies may be better served by focusing on the continued development of reliable and valid treatment approaches that address the complex psychosocial factors that may be maintaining or exacerbating pain and disability. They maintain that the gold-standard for assessing pain intensity and disability is, rightfully so, the patient’s self-report.

Study Methods:

This was a narrative review of the literature on this topic, and as such no formal methodology was outlined nor were statistical methods applied.

Study Strengths / Weaknesses:

Limitations: This was a narrative review. No formal analysis was done to provide any statistical insight about the clinical use of these tools. This is likely because it is inherently difficult to prove genuine malingering, outside of catching someone red-handed. Therefore, there’s probably very little data to analyze. Many RCTs use simulated malingering as comparison groups, which is truly a weakness of whatever studies have been conducted and published so far. Of course, ruling out other psychiatric illnesses prior to concluding the patient is feigning is fundamentally important.

Strengths: I appreciate that the authors didn’t just say that all these tests are meaningless without explaining that some of the behaviours and phenomena we observe as clinicians might be due to other psychiatric disorders or central neuroplastic changes. This is important, because we must see these patients from the standpoint that they are genuine and believable, and not from the standpoint that they are ‘trying to cheat the system’. Malingering is rare – so it shouldn’t be our default suspicion about a person just because we’ve been taught as much. One further detail: if you (re-)read Waddell’s original texts, he states outright that the presence of 3 or more Waddell’s Signs is an indication that a more robust bio-psycho-social evaluation is necessary, and that surgery is less likely to be successful in these patients. In later publications, Waddell spoke out about his signs NOT being associated with malingering in any meaningful way. Unfortunately, this is the way many people were taught about them!

Additional References:

  1. Gureje O, Von Korff M, Simon GE, Gater R: Persistent pain and well-being: A World Health Organization study in primary care. JAMA 1998; 280: 147-151.
  2. Johannes CB, Le TK, Zhou X, et al. The prevalence of chronic pain in United States adults: Results of an Internet-based survey. J Pain 2010; 11: 1230-1239.
  3. Tsang A, Von Korff M, Lee S, et al. Common chronic pain conditions in developed and developing countries: Gender and age differences and comorbidity with depression-anxiety disorders. J Pain 2008; 9: 883-891.
  4. Greve KW, Ord JS, Bianchini KJ, Curtis KL: Prevalence of malingering in patients with chronic pain referred for psychologic evaluation in a medico-legal context. Arch Phys Med Rehabil 2009; 90: 1117-1126.
  5. Kay NR & Morris-Jones H. Pain clinic management of medico-legal litigants. Injury 1998; 29: 305-308.
  6. Mittenberg W, Patton C, Canyock EM & Condit DC. Base rates of malingering and symptom exaggeration. J Clin Exp Neuropsychol 2002; 24: 1094-1102.
  7. Lees-Haley PR, English LT & Glenn WJ. A Fake Bad Scale on the MMPI-2 for personal injury claimants. Psychol Rep 1991; 68: 203-210.
  8. Reynolds CR. Common sense, clinicians, and actuarialism in the detection of malingering during head injury litigation. Detection of Malingering During Head Injury Litigation. New York, NY, Springer, 1998. p. 261-286
  9. Bianchini KJ, Greve KW & Glynn G. On the diagnosis of malingered pain-related disability: Lessons from cognitive malingering research. Spine J 2005; 5:404-417.
  10. Barsky AJ & Borus JF: Functional somatic syndromes. Ann Intern Med 1999; 130:910-921.