The Development of the Inventory of Problems-29: A Brief Self-Administered Measure for Discriminating Bona Fide From Feigned Psychiatric and Cognitive Complaints.

This article describes the development of the Inventory of Problems-29 (IOP-29), a new, short, paper-and-pencil, self-administered measure of feigned mental and cognitive disorders. Four clinical comparison simulation studies were conducted. Study 1 (n = 451) selected the items and produced an index of potential feigning. Study 2 (n = 331) scaled this index to produce a probability score, and examined its psychometric properties. Study 3 tested the generalizability of Study 2's findings with 2 additional samples (ns = 128 and 90). Results supported the utility of the IOP-29 for discriminating bona fide from feigned psychiatric and cognitive complaints. Validity was demonstrated in feigning mild traumatic brain injury, psychosis, posttraumatic stress disorder, and depression. Within the independent samples of Studies 2 and 3, the brief IOP-29 performed similarly to the MMPI-2 and Personality Assessment Inventory, and perhaps better than the Test of Memory Malingering. Classifications within these samples with base rates of .5 produced sensitivity, specificity, positive predictive power, and negative predictive power statistics of about .80. Further research is needed testing the IOP-29 in ecologically valid field studies.