Kelly L. Curtis

Detecting Malingering in Traumatic Brain Injury and Chronic Pain: A Comparison of Three Forced-Choice Symptom Validity Tests

Individual and joint malingering detection accuracy of the Portland Digit Recognition Test (PDRT), Test of Memory Malingering (TOMM), and Word Memory Test (WMT) was examined in traumatic brain injury (TBI; 43 non-malingering, 27 malingering) and chronic pain (CP; 42 non-malingering, 58 malingering) using a known-groups design. At published cutoffs, the PDRT and TOMM were very specific but failed to detect about 50% of malingerers; the WMT was sensitive but prone to false positive errors. ROC analyses demonstrated comparable accuracy across all three tests. Joint classification accuracy was superior to that of the individual tests. Clinical and research implications are discussed.

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 MNDand 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.

Memory in traumatic brain injury: the effects of injury severity and effort on the Wechsler Memory Scale-III.

This study examined the effects of traumatic brain injury (TBI) on Wechsler Memory Scale-III (WMS-III) performance. Since poor effort potentially contaminates results, effort was explicitly assessed and controlled using two well-validated cognitive validity indicators, the Portland Digit Recognition Test (PDRT) and Reliable Digit Span (RDS). Participants were 44 mild TBI patients with good effort, 48 mild TBI patients with poor effort, and 40 moderate-severe TBI patients with good effort. A dose-response relationship between injury severity and WMS-III performance was demonstrated. Effect size calculations showed that the good effort mild TBI patients did not differ from normal (average Cohens d= 0.07) while moderate-severe TBI had a moderate effect on WMS-III scores (average Cohens d=-0.52). Consistent with previous literature, the moderate-severe TBI group scored the lowest on WMS-III Visual indices. Effort had a larger effect than injury severity on WMS-III scores (average Cohens d=-1.27). Clinical implications of these findings are discussed.

Verbal Fluency Indicators of Malingering in Traumatic Brain Injury: Classification Accuracy in Known Groups

A known-groups design was used to determine the classification accuracy of verbal fluency variables in detecting Malingered Neurocognitive Dysfunction (MND) in traumatic brain injury (TBI). Participants were 204 TBI and 488 general clinical patients. The Slick et al. (1999) criteria were used to classify the TBI patients into non-MND and MND groups. An educationally corrected FAS Total Correct word T-score proved to be the most accurate of the several verbal fluency indicators examined. Classification accuracy of this variable at specific cutoffs is presented in a cumulative frequency table. This variable accurately differentiated non-MND from MND mild TBI patients but its accuracy was unacceptable in moderate/severe TBI. The clinical application of these findings is discussed.

Detecting Malingered Pain-Related Disability: Classification Accuracy of the Test of Memory Malingering

This study used criterion groups validation to determine the accuracy of the Test of Memory Malingering (TOMM) in detecting malingered pain-related disability (MPRD) across a range of cutoffs in chronic pain patients undergoing psychological evaluation (n = 604). Data from patients with traumatic brain injury (n = 45) and dementia (n = 59) are presented for comparison. TOMM scores decreased and failure rates increased as a function of greater external evidence of intentional under-performance. The TOMM detected from 37.5% to 60.2% of MPRD patients, depending on the cutoff. False positive (FP) error rates ranged from 0% to 5.1%. Accuracy data for Trial 1 are also reported. In chronic pain the original cutoffs produced no FP errors but were associated with high false negative error rates. Higher cutoffs increased sensitivity without adversely affecting specificity. The relevance of these findings to research and clinical practice is discussed.

The Reliable Digit Span test in chronic pain: classification accuracy in detecting malingered pain-related disability.

This study used criterion groups validation (known-groups design) to examine the classification accuracy of the Reliable Digit Span test (RDS) in a large group of chronic pain patients referred for psychological evaluation. The sample consisted of 612 patients classified into one of six groups based on evidence of malingered pain-related disability (MPRD): No-Incentive, Not MPRD; Incentive-Only, Not MPRD; Indeterminate; Possible MPRD; Probable MPRD; Definite MPRD. A total of 30 college student simulators were also included. Lower average RDS scores and higher rates of RDS failure were seen in patients classified as MPRD and in simulators. Consistent with previous literature in a variety of populations, RDS < = 6 provided the most accurate differentiation between MPRD and non-MPRD pain patients. Clinical implications are discussed.

The Wechsler Adult Intelligence Scale-III and Malingering in Traumatic Brain Injury: Classification Accuracy in Known Groups.

A known-groups design was used to determine the classification accuracy of Wechsler Adult Intelligence Scale—III (WAIS-III) variables in detecting malingered neurocognitive dysfunction (MND) in traumatic brain injury (TBI). TBI patients were classified into the following groups: (a) mild TBI not-MND (n = 26), (b) mild TBI MND (n = 31), and (c) moderate/severe (M/S) TBI not-MND (n = 26). A sample of 80 general clinical patients was used for comparison. Verbal IQ, Verbal Comprehension Index, and Working Memory Index detected approximately 25% of malingerers with a false positive (FP) error rate of approximately 5% in the mild TBI group. Comparable FP rates were obtained in M/S TBI. FP rates for Performance IQ, Perceptual Organization Index, and Processing Speed Index were acceptable in mild TBI but too high in M/S TBI. Previously studied specialized indicators (Vocabulary minus Digit Span and the Mittenberg formula) failed to differentiate malingerers from nonmalingerers. The clinical application of these findings is discussed.

Are the Original and Second Edition of the California Verbal Learning Test Equally Accurate in Detecting Malingering

This two-part study sought to determine the equivalence of the California Verbal Learning Tests (CVLT-1 and CVLT-2) in the detection of malingering in traumatic brain injury (TBI) and chronic pain. Part 1 compared a variety of scores from the two versions in carefully matched patient groups. Part 2 used criterion groups (known-groups) methodology to examine the relative rates of false positive (FP) errors across the two versions. Participants were 442 TBI (CVLT-1 = 310; CVLT-2 = 132) and 378 chronic pain patients (CVLT-1 = 250; CVLT-2 = 128). Overall, the CVLT-2 was more difficult than the CVLT-1, with the chronic pain patients showing larger version effects than the TBI patients. The two versions of the CVLT were equally accurate in detecting malingering in TBI and chronic pain. However, they were not interchangeable. The use of CVLT-1 cutoffs with the CVLT-2 may result in an increased risk of FP error. Appropriate cutoff adjustment in clinical practice is recommended.

Detecting Malingered Pain-Related Disability: Classification Accuracy of the Portland Digit Recognition Test

This study used criterion groups validation to determine the classification accuracy of the Portland Digit Recognition Test (PDRT) at a range of cutting scores in chronic pain patients undergoing psychological evaluation ( n = 318), college student simulators ( n = 29), and patients with brain damage ( n = 120). PDRT scores decreased and failure rates increased as a function of greater independent evidence of intentional underperformance. There were no differences between patients classified as malingering and college student simulators. The PDRT detected from 33% to nearly 60% of malingering chronic pain patients, depending on the cutoff used. False positive error rates ranged from 3% to 6%. Scores higher than the original cutoffs may be interpreted as indicating negative response bias in patients with pain, increasing the usefulness and facilitating the clinical application of the PDRT in the detection of malingering in pain.

CRITERION GROUPS VALIDATION OF THE SEASHORE RHYTHM TEST AND SPEECH SOUNDS PERCEPTION TEST FOR THE DETECTION OF MALINGERING IN TRAUMATIC BRAIN INJURY

A criterion-groups validation was used to determine the classification accuracy of the Seashore Rhythm Test (SRT) and Speech Sounds Perception Test (SSPT) in detecting malingered neurocognitive dysfunction (MND) in traumatic brain injury (TBI). TBI patients were classified into the following groups: (1) Mild TBI Not-MND (n = 24); (2) Mild TBI MND (n = 27); and (3) Moderate/Severe TBI Not-MND (n = 23). A sample of 90 general clinical patients was utilized for comparison. Results showed that both SRT correct and SSPT errors differentiated malingerers from non-malingerers in the Mild TBI sample. At 96% specificity, sensitivities were 37% for SRT correct and 59% for SSPT errors. Joint classification accuracy showed that the best accuracy was achieved when using a cut-off associated with a 4% false positive error rate in the Mild TBI sample. Specificity was considerably lower in the Moderate/Severe TBI and General Clinical groups. The clinical application of these findings is discussed.