A Clinical Comparison, Simulation Study Testing the Validity of SIMS and IOP-29 with an Italian Sample

Abstract

The Inventory of Problems -29 (IOP-29) was recently introduced as a brief, easy-to-use measure of non-credible mental and cognitive symptoms that may be applied to a wide variety of contexts or clinical conditions. The current study compared its validity in discriminating bonafide versus feigned (via experimental malingering paradigm) psychopathology against that of the Structured Inventory of Malingered Symptomatology (SIMS). Specifically, 452 Italian adult volunteers participated in this study: 216 were individuals with mental illness who were asked to take the SIMS and IOP-29 honestly, and 236 were nonclinical participants (experimental simulators) who took the same two tests with the instruction to feign a psychopathological condition. Two main, broad categories of symptom presentations were investigated: (a) psychotic spectrum disorders and (b) anxiety, depression, and/or trauma-related disorders. Data analysis compared the effect sizes of the differences between the patients and experimental simulators, as well as the AUC and classification accuracy statistics for both the SIMS and IOP-29. The results indicate that the IOP-29 outperformed the SIMS, with the differences between the two tools being more notable within the psychotic (IOP-29 vs. SIMS: d = -1.80 vs. d = -1.06; AUC = .89 vs. AUC = .79) than within the anxiety, depression, and/or trauma related subgroup (IOP-29 vs. SIMS: d = -2.02 vs. d = -1.62; AUC = .90 vs. AUC = .86). This study also demonstrates that the IOP-29, with its single cutoff score, is generalizable culturally and linguistically from the U.S. (English) to Italy (Italian).

Using the inventory of problems – 29 (IOP-29) with the Test of Memory Malingering (TOMM) in symptom validity assessment: A study with a Portuguese sample of experimental feigners

“…In their developmental research, Viglione et al (2017) found that its classification accuracy was similar to that of the longer and more complex Personality Assessment Inventory (PAI; Morey, 1991Morey, , 2007 and Minnesota Multiphasic Personality Inventory (MMPI-2; Butcher et al, 2001;Green, 1991) when assessing various symptom presentations, and perhaps better than that of the TOMM when evaluating depression-related complaints. More recently, Giromini, Viglione, Pignolo and Zennaro (2018) conducted an independent, clinical comparison, simulation study with 216 bona fide patients and 236 experimental feigners (malingering experimental paradigm), and found that the classification accuracy of the IOP-29 compared favorably to that of the two-and-a-half times longer SIMS. Indeed, when considering the entire sample (N = 452) the receiver operator characteristic curve (area under the curve; AUC) was .89 (SE = .02) for the IOP-29 vs. .83 (SE = .02) for the SIMS; Cohen's d effect sizes were 1.93 for the IOP-29 vs. 1.39 for the SIMS.…”

Indicators to distinguish symptom accentuators from symptom producers in individuals with a diagnosed adjustment disorder: A pilot study on inconsistency subtypes using SIMS and MMPI-2-RF

“…A further example is the Inventory of Problems-29 (IOP-29) [22], a 29-item easy-to-use measure of non-credible mental and cognitive symptoms. Studies using this instrument yielded encouraging results in the detection of malingering [23,24] and indicated that it can be used in a multimethod symptom validity assessment along with TOMM [25]. Another example is the Structured Inventory of Malingered Symptomatology (SIMS) [26] is a 75-item multi-axial self-report questionnaire validated with clinical-forensic, psychiatric, and non-clinical populations.…”

An Inventory of Problems–29 Study on Random Responding Using Experimental Feigners, Honest Controls, and Computer-Generated Data

“…In terms of demographics, the combined sample encompassing 891 adult volunteers was highly heterogeneous regarding gender (men = 44.4%), age (M ≈ 42, SD ≈ 14), 1 education (high school or less = 61.9%), racial characterization (about 70% came from Italy, and about 30% -of which slightly more than half defined themselves as "White" -from the US), and marital status (in a relationship = 58.3%) (for details, see Giromini et al, 2018;Giromini et al, 2019a;Viglione et al, 2017). The great majority of this sample, i.e., n = 791, was used to develop the Hon-RRS (Honest Responders -Developmental Sample); 100 were randomly extracted to be used for cross-validation purposes (Honest Responders -Validation Sample).…”

“…As for the sample of experimental simulators, an archival data set of 910 IOP-29s, 274 from the US (Viglione et al, 2017) and 636 from Italy (236 from Giromini et al, 2018; 400 from Giromini et al, 2019a), contributed to this research. As for the 400 IOP-29s from Giromini et al (2019a), they were taken from the second condition described above, in which participants were asked to take the test as if they wanted to convince the examiner that they were mentally ill.…”

“…In all cases, simulators were provided with a brief scenario or vignette from real-life situations, and were warned not to be too dramatic in their symptom presentations, so to improve their ability to feign in a more credible way (Rogers & Bender, 2013). In terms of conditions to be feigned, each participant was instructed to pretend to suffer Also the combined, experimental simulators sample was highly heterogeneous regarding (men = 43.2%), age (M ≈ 38, SD ≈ 13), education (high school or less = 54.0%), racial characterization (about 70% came from Italy, and about 30% -of which slightly more than half defined themselves as "White" -from the US), and marital status (in a relationship = 40.6%) (for details, see Giromini et al, 2018;Giromini et al, 2019a;Viglione et al, 2017). These data served to develop and validate an indicator of infrequency and an indicator of inconsistency based on responding patterns of experimental simulators.…”