Prevalence of malingering in patients with chronic pain referred for psychologic evaluation in a medico-legal context.

OBJECTIVE: To provide an empirical estimate of the prevalence of malingered disability in patients with chronic pain who have financial incentive to appear disabled. DESIGN: Retrospective review of cases. SETTING: A private neuropsychologic clinic in a southeastern metropolitan area. PARTICIPANTS: Consecutive patients (N=508) referred for psychologic evaluation related to chronic pain over a 10-year period (1995-2005). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Prevalence of malingering was examined using 2 published clinical diagnostic systems (Malingered Pain-Related Disability and Malingered Neurocognitive Dysfunction) as well as statistical estimates based on well validated indicators of malingering. RESULTS: The prevalence of malingering in patients with chronic pain with financial incentive is between 20% and 50% depending on the diagnostic system used and the statistical model's underlying assumptions. Some factors associated with the medico-legal context such as the jurisdiction of a workers' compensation claim or attorney representation were associated with slightly higher malingering rates. CONCLUSIONS: Malingering is present in a sizable minority of patients with pain seen for potentially compensable injuries. However, not all excess pain-related disability is a result of malingering. It is important not to diagnose malingering reflexively on the basis of limited or unreliable findings. A diagnosis of malingering should be explicitly based on a formal diagnostic system.

Detecting malingered pain-related disability with the pain catastrophizing scale: a criterion groups validation study.

Objective: Intentional exaggeration of symptoms is a potential problem in contexts where there are financial incentives to appear disabled. Therefore, calibration of tools to accurately evaluate malingering in these contexts is important. The present study used a criterion groups validation design to determine the ability of the Pain Catastrophizing Scale (PCS) to detect Malingered Pain-Related Disability (MPRD). Method: Individuals meeting inclusionary/exclusionary criteria were selected for this study (n = 219) from a larger dataset of chronic pain patients referred for a psychological evaluation. Patients were classified into malingering groups using the Bianchini, Greve, and Glynn classification system for MPRD. PCS T scores were compared in patients who met MPRD criteria and those who showed no indication of malingering on multiple validity tests. Results: No group differences were observed regarding medicolegal and injury characteristics. Group analyses showed that the Not MPRD group had a significantly lower PCS score (Estimated Marginal Mean [EMM] = 62.3) than all other groups. The Probable and Definite MPRD groups (which together comprise the MPRD group) had the highest PCS T scores (EMM = 77.2 and EMM = 83.8, respectively). A PCS T score of 81 was associated with a 7% false-positive (FP) error rate, sensitivity of 47%, likelihood ratio (LR) of 6.7, and a positive predictive value (PPV) of .74 at base rates around 30%. Conclusions: PCS T scores greater than 81 should raise concerns about the validity of the PCS report and provide additional information that can be helpful in identifying intentional symptom exaggeration in patients with chronic pain.

The relationship between the modified somatic perception questionnaire and dynamic platform posturography.

OBJECTIVE: To analyze if patients whose vestibular symptoms are associated with nonorganic sway patterns show more evidence of somatization and/or malingering than patients whose vestibular symptoms are associated with normal or physiologically abnormal sway patterns observed in people with documented vestibular pathologic findings. PATIENTS: One hundred fifteen patients with complaints of vestibular dysfunction and hearing impairment. INTERVENTIONS: Computerized dynamic posturography (CDP) and completion of the Modified Somatic Perception Questionnaire (MSPQ)--a validated test for the detection of malingering. MAIN OUTCOME MEASURES: Computerized dynamic posturography results classified into 4 categories (normal, physiologic abnormal, borderline-aphysiologic, and aphysiologic) were correlated with the results of the MSPQ. RESULTS: A significant CDP group effect on the MSPQ, with the aphysiologic patients scoring significantly higher than the other groups. Moreover, a significantly higher proportion of aphysiologic patients scored more than the MSPQ cutoffs for malingering. CONCLUSION: Results indicate that patients who have aphysiologic CDP sway patterns are more likely to have higher MSPQ scores. Both aphysiologic CDP results and high MSPQ scores have been associated with intentional exaggeration. These results indicate that patients with both aphysiologic CDP findings and high MSPQ scores are more likely to be intentionally exaggerating their balance-related complaints and deficits.

Observed versus estimated IQ as an index of malingering in traumatic brain injury: classification accuracy in known groups.

This study examined the classification accuracy of observed WAIS-III VIQ, PIQ, and FSIQ minus Barona-estimate differential scores in the detection of Malingered Neurocognitive Dysfunction (MND) in Traumatic Brain Injury (TBI) using a known-groups design. Two hundred eleven TBI patients were assigned to one of three groups: Not-MND (n = 87), Indeterminate (n = 68), and MND (n = 56). A General Clinical Sample of 93 no-incentive patients (e.g., CVA, memory disorder) was also included to better study specificity. The VIQ differential accurately differentiated MND from Not-MND TBI patients regardless of injury severity. The PIQ differential was only accurate in mild TBI and did not add incremental validity to the VIQ differential. This study indicates that VIQ declines of greater than 24 points are rare except in very severe TBI. Particularly in mild TBI, such differentials likely indicate intentional suppression of WAIS-III performance consistent with MND. Clinical application is discussed.

Classification accuracy of MMPI-2 validity scales in the detection of pain-related malingering: a known-groups study.

The purpose of this study was to determine the accuracy of Minnesota Multiphasic Personality Inventory 2nd edition (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) validity indicators in the detection of malingering in clinical patients with chronic pain using a hybrid clinical-known groups/simulator design. The sample consisted of patients without financial incentive (n = 23), nonmalingering patients with financial incentive (n = 34), patients definitively determined to be malingering based on published criteria ( n = 32), and college students asked to simulate pain-related disability (n = 26). The MMPI-2 validity scales differentiated malingerers from nonmalingerers with a high degree of accuracy. Hypochondriasis and Hysteria were also effective. For all variables except Scale L, more extreme scores were associated with higher specificity. This study demonstrates that the MMPI-2 is capable of differentiating intentional exaggeration from the effects on symptom report of chronic pain, genuine psychological disturbance, and concurrent stress associated with pursuing a claim in a medico-legal context.

Clusters of financially incentivized chronic pain patients using the Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF).

The Minnesota Multiphasic Personality Inventory (MMPI)-2 Restructured Form (MMPI-2-RF) has been shown to have clinical utility in the assessment of individuals with chronic pain (e.g., predicting surgical outcomes). The purpose of this study was to explore the ability of the MMPI-2-RF Validity Scales in profiling patients with chronic pain who had external financial incentive (e.g., workers' compensation claims) and determine the associations between Validity Scale response patterns and important outcomes. Cluster analysis identified 2 similarly sized clusters of patients with very different MMPI-2-RF profiles. Cluster 1 was characterized by valid responding and showed mean elevations on the somatic and low positive emotion Restructured Clinical scales. Cluster 2 was characterized by patients overreporting on the MMPI-2-RF Validity Scales, who also demonstrated elevations on 7 of the 9 RC scales. Cluster membership was differentially associated with clinical variables: patients in Cluster 2 had greater self-reported pain and disability, were less likely to have spine-related findings on imaging and were more likely to be classified as probable or definite malingerers. These results support the utility of the MMPI-2-RF Validity scales in distinguishing between credible and noncredible responses from patients with chronic pain seen within a medico-legal context. (PsycINFO Database Record

Classification accuracy of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2)-Restructured form validity scales in detecting malingered pain-related disability.

The symptom reports of individuals with chronic pain are multidimensional (e.g., emotional, cognitive, and somatic) and significantly contribute to increased morbidity and lost work productivity. When pain occurs in the context of a legally compensable event, reliable assessment of a patient's multifactorial symptom experience during psychological or neuropsychological evaluations is a necessity. The Validity Scales of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) have been shown useful in identifying symptom overreporting and feigning within chronic pain samples and a number of studies have emerged supporting the use of the MMPI-2-Restructured Form (MMPI-2-RF) in the detection of simulated or feigned impairment in a variety of populations. To date, only 1 other study exists examining the ability of the MMPI-2-RF to detect exaggerated complaints using a strict operationalization of malingering exclusive to chronic pain samples. The purpose of this study was to examine the classification accuracy of MMPI-2-RF Validity Scales in a group of patients with chronic pain using a criterion-groups design. The final sample consisted of 501 clinical chronic pain patients assigned to groups based on the Bianchini, Greve, and Glynn (2005) criteria for Malingered Pain-Related Disability (MPRD). Results showed that all MMPI-2-RF Validity Scales differentiated malingerers from nonmalingerers with a high degree of accuracy. At cut-offs associated with ≥95% Specificity, Sensitivities ranged from 15% (Fs) to 60% (Response Bias Scale; RBS). This study demonstrates that the MMPI-2-RF Validity Scales are capable of differentiating intentional symptom exaggeration from genuine complaints in a sample of incentivized chronic pain patients. (PsycINFO Database Record

Malingering in toxic exposure: classification accuracy of reliable digit span and WAIS-III Digit Span scaled scores.

This study examined the sensitivity and false-positive error rate of reliable digit span (RDS) and the WAIS-III Digit Span (DS) scaled score in persons alleging toxic exposure and determined whether error rates differed from published rates in traumatic brain injury (TBI) and chronic pain (CP). Data were obtained from the files of 123 persons referred for neuropsychological evaluation related to alleged exposure to environmental and industrial substances. Malingering status was determined using the criteria of Slick, Sherman, and Iverson (1999). The sensitivity and specificity of RDS and DS in toxic exposure are consistent with those observed in TBI and CP. These findings support the use of these malingering indicators in cases of alleged toxic exposure and suggest that the classification accuracy data of indicators derived from studies of TBI patients may also be validly applied to cases of alleged toxic exposure.

The prevalence of cognitive malingering in persons reporting exposure to occupational and environmental substances.

OBJECTIVE: Directly estimate the prevalence of cognitive malingering in persons claiming exposure to occupational and environmental substances. METHODS: Retrospective review of 128 neuropsychological cases with financial incentive. Estimates were based on two methods: (1) clinical identification using the Slick, Sherman and Iverson criteria for malingered neurocognitive dysfunction (MND), and (2) statistical modeling based on patient performance on several individual psychometric indicators of malingering. RESULTS: The prevalence based on the clinical method was 40%. The statistically based estimates ranged from 30% to more than 45% depending on model parameters. Different incentive parameters may influence prevalence. CONCLUSIONS: Cognitive malingering in toxic exposure is common and must be adequately addressed in the clinical neuropsychological assessment of toxic exposure and in research on its neurocognitive effects or findings will likely over-estimate the degree of cognitive impairment and related disability.

Should the Retention trial of the Test of Memory Malingering be optional?

The present study examined the false negative error rate associated with the optional use of the Retention trial the Test of Memory Malingering (TOMM). TOMM scores from 150 traumatic brain injury and 150 chronic pain patients were examined. Results indicated that early termination of the TOMM resulted in 3% of patients going undetected by the TOMM. The practical cost of this error was minimized by the inclusion of at least one other SVT. Clinical implications are discussed.

Classification accuracy of the Test of Memory Malingering in persons reporting exposure to environmental and industrial toxins: Results of a known-groups analysis.

This study used a known-groups design to examine the classification accuracy of the Test of Memory Malingering in detecting cognitive malingering in patients claiming cognitive deficits due to exposure to environmental and industrial toxins. Thirty-three patients who met Slick et al. criteria for Malingered Neurocognitive Dysfunction were compared to 17 toxic exposure patients negative for evidence of malingering, 14 TBI patients and 22 memory disorder patients, both groups without incentive. The original cutoffs (<45) for Trial 2 and Retention demonstrated perfect specificity (0% false positive error rate) and impressive sensitivity (>50%). These findings indicate the TOMM can be used with confidence as an indicator of negative response bias in cases of cognitive deficits attributed to exposure to alleged neurotoxic substances.

Pain, malingering and the WAIS-III Working Memory Index.

BACKGROUND CONTEXT: Pain patients often report cognitive symptoms, and many will include them in their claims of disability. There is empirical evidence that patients with pain do experience problems on attention-demanding cognitive tasks, but the results are mixed and the potential impact of exaggeration in the context of pain-related litigation has not been addressed. PURPOSE: 1) Examine the impact of pain and malingering on attention; 2) determine if the Working Memory Index (WMI) of the Wechsler Adult Intelligence Scale-3 (WAIS-III) can reliably detect malingering. STUDY DESIGN/SETTING: Study 1: simulator design; Study 2: clinical known-groups design. PATIENT SAMPLE: Study 1 used healthy college students; Study 2 used chronic pain patients and neurological patients. OUTCOME MEASURES: The WMI and its constituent subtests. METHODS: Study 1: College students were administered the WMI under three conditions: standard administration, with cold-pressor induced pain, or with instructions to simulate impairment due to pain. Study 2: Known-groups design in which the WMI was examined in non-malingering and definite malingering chronic pain patients, non-malingering moderate-severe traumatic brain injury, and memory disorder patients seen for routine psychological evaluation. Malingering was operationalized using published criteria. RESULTS: There were no group differences in WMI or its subtests among non-malingering groups, but some individual clinical patients with pain did score at a level suggestive of attentional impairment. The lowest scores were found in the simulated malingering college students and definite malingering clinical pain groups, in which about half scored worse than 95% of the non-malingering clinical patients. CONCLUSIONS: This study demonstrated that even when controlling for exaggeration some pain patients do exhibit problems with attentional function. However, significant impairment in WMI performance (eg, index score

California verbal learning test indicators of Malingered Neurocognitive Dysfunction: sensitivity and specificity in traumatic brain injury.

The present study used well-defined traumatic brain injury (TBI) and mixed neurological (other than TBI) and psychiatric samples to examine the specificity and sensitivity to Malingered Neurocognitive Dysfunction (MND) of four individual California Verbal Learning Test (CVLT) variables and eight composite CVLT malingering indicators. Participants were 275 traumatic brain injury and 352 general clinical patients seen for neuropsychological evaluation. The TBI patients were assigned to one of five groups using the Slick, Sherman, and Iverson (1999) criteria: no incentive, incentive only, suspect, and malingering (both Probable MND and Definite MND). Within TBI, persons with the strongest evidence for malingering (Probable and Definite) had the most extreme scores. Good sensitivity (approximately 50%) in the context of excellent specificity (> 95%) was found in the TBI samples. Issues related to the appropriate clinical application of these data are discussed.

Psychological evaluation of the emotional effects of a community toxic exposure.

OBJECTIVE: We sought to assess the emotional effects of a major community toxic release while controlling the potential effects of response bias associated with litigation. METHODS: Participants included 152 exposed adult litigants and a matched unexposed comparison group (n = 76). Psychological assessment methods included: (1) Minnesota Multiphasic Personality Inventory-2; (2) Symptom Checklist-90-Revised; and (3) Impact of Event Scale-Revised. RESULTS: Ten to 40% of the exposed group demonstrated emotional distress (compared with a 5% comparison baseline) depending on indicator and cutoff score used. CONCLUSIONS: The psychological consequences of a community toxic exposure were present even when exaggeration was carefully controlled. Accounting for exaggeration in the assessment of subjective psychological complaints provides a more accurate view of the subjective emotional state of persons who have experienced toxic exposure thereby facilitating appropriate clinical management of their mental health needs.

Detection of feigned tactile sensory loss using a forced-choice test of tactile discrimination and other measures of tactile sensation.

OBJECTIVE: Intentional exaggeration of disability is a risk in work injuries but is hard to reliably detect clinically. This study examined the accuracy of tactile sensory threshold and forced-choice discrimination measures in detecting feigned sensory loss. METHODS: Participants (n = 80) were randomly assigned to one of four sensory loss groups: (1) none; (2) partial; (3) full; or (4) feigned. Sensory data were collected for the upper extremities. RESULTS: Tactile thresholds greater than 0.5 g, discriminability less than 0.50, or forced-choice scores less than 90% were associated with a very low probability of false-positive errors. CONCLUSIONS: Below-chance scores are definitive evidence that the sensory loss is intentionally feigned. Scores beyond cut-offs should raise the clinician's suspicion of malingering if there is no physical basis for sensory loss.

Detection and diagnosis of malingering in electrical injury.

This paper sought to demonstrate that diagnosable malingering does occur in Electrical Injury (EI) and examine the relationship of malingering to potential indicators of the presence and severity of neurological injury. Eleven consecutive EI patients seen for neuropsychological evaluation were presented. Over half the patients met the Slick et al. (1999) criteria for at least Probable MND. Most of the MND patients lacked evidence of a biologically meaningful exposure to electrical current. These findings highlight the importance of considering biological markers of neurological injury and of non-neurological factors, including effort/malingering, in the study of the neurocognitive consequences of EI.

Latent structure of the Wisconsin Card Sorting Test: a confirmatory factor analytic study.

The present study represents the first large scale confirmatory factor analysis of the Wisconsin Card Sorting Test (WCST). The results generally support the three factor solutions reported in the exploratory factor analysis literature. However, only the first factor, which reflects general executive functioning, is statistically sound. The secondary factors, while likely reflecting meaningful cognitive abilities, are less stable except when all subjects complete all 128 cards. It is likely that having two discontinuation rules for the WCST has contributed to the varied factor analytic solutions reported in the literature and early discontinuation may result in some loss of useful information. Continued multivariate research will be necessary to better clarify the processes underlying WCST performance and their relationships to one another.

Test of Memory Malingering Performance is unaffected by laboratory-induced pain: implications for clinical use.

The Test of Memory Malingering (TOMM) is a well-validated and widely used forced-choice symptom validity test. However, little is known about how TOMM performance is affected by pain. The present study evaluated the sensitivity of the TOMM to pain induced in healthy participants via the cold-presser test. Participants (n=20 per group) were administered the TOMM under one of three conditions: (1) standard instructions; (2) instructions to simulate pain-related memory deficit in pursuit of personal injury litigation; (3) while experiencing cold-induced pain. Results indicate that TOMM performance was unaffected by laboratory-induced moderate to severe pain and support the TOMM's use in evaluating clinical patients with pain.

A comparison of anticonvulsants in the treatment of impulsive aggression.

This study compared the behavioral effects of 3 anticonvulsants in impulsive aggressive men. In a double-blind, placebo-controlled, parallel groups design, participants were randomly assigned to 1 of 4 6-week treatments: phenytoin (n = 7), carbamazepine (n = 7), valproate (n = 7), or placebo (n = 8). The efficacy measure was the average aggression score, a global severity index from the Overt Aggression Scale (J. M. Silver & S. C. Yudofsky, 1991). Analysis showed a significant reduction in impulsive aggression during all 3 anticonvulsant conditions compared with placebo. However, the treatment effect during carbamazepine administration was slightly delayed compared with phenytoin and valproate. These findings suggest that increased use of anticonvulsants could make a significant impact in the control of impulsive aggression in both mental health and criminal justice settings.

On the diagnosis of malingered pain-related disability: lessons from cognitive malingering research.

BACKGROUND CONTEXT: Pain-related disability is a complex phenomenon. Malingering is a potential factor in the management of patients with pain. Methodological problems and inappropriate expectations regarding diagnostic accuracy have hampered the study of malingering detection in pain. In contrast, the study of cognitive malingering in neuropsychology has led to the development of many highly accurate and reliable detection techniques. This paper applies the methods and logic that have been successful for identifying cognitive malingering to the problem of malingering in patients with pain. PURPOSE: Outline the logic of a research methodology for studying malingering detection in pain and introduce a system for the diagnosis of malingering in pain. STUDY DESIGN: Literature review and conceptual synthesis. METHODS: Examination of the research methodology and diagnostic scheme used in the study of cognitive malingering; adaptation of these methods to the problem of malingering in pain. RESULTS: Lessons derived from the study of cognitive malingering were used to generate recommendations to enhance research into detection and diagnosis of malingered pain-related disability. A comprehensive, multidimensional system for diagnosing malingering in pain-related disability was proposed. CONCLUSIONS: Pain-related disability is a multifaceted phenomenon, therefore malingering can occur in different and sometimes multiple dimensions. It is presently possible to accurately detect and diagnose malingering in some patients with pain. More work is needed for some detection techniques to be appropriately calibrated in pain populations. This work must focus on controlling the false positive error rate.