Ecological validity of the WMS-III Rarely Missed Index in personal injury litigation

The purpose of this study was to evaluate the clinical utility of the Rarely Missed Index (RMI) to detect cognitive exaggeration in 78 nonlitigant patients (i.e., Mixed Clinical group) and 158 personal injury litigants (i.e., 20 Suspected Exaggerators, 12 Borderline Exaggerators, 126 Genuine Responders). The base rate for probable malingered neurocognitive dysfunction in the litigant sample was 12.7%. The false positive error rate of the RMI in the Genuine Responder and Mixed Clinical group ranged from 5.4% to 8.6%. Positive RMI scores were found in 25% and 41.7% of the Suspected Exaggerator and Borderline Exaggerator groups respectively. The clinical utility of the RMI to identify Suspected Exaggerators versus individuals in the Genuine Responder and Mixed Clinical groups revealed low sensitivity (sensitivity = .25), very high specificity (range = .91 to .95), moderate positive predictive power (range = .50 to .71), and moderate to high negative predictive power (range = .68 to .83). These results do not support the use of the RMI as a reliable predictor of cognitive exaggeration.