Classification accuracy and resistance to coaching of the Spanish version of the Inventory of Problems-29 and the Inventory of Problems-Memory: A simulation study with mTBI patients

Abstract

Objective: The present study aims to evaluate the classification accuracy and resistance to coaching of the Inventory of Problems-29 (IOP-29) and the IOP-Memory (IOP-M) with a Spanish sample of patients diagnosed with mild traumatic brain injury (mTBI) and healthy participants instructed to feign. Method: Using a simulation design, 37 outpatients with mTBI (clinical control group) and 213 non-clinical instructed feigners under several coaching conditions completed the Spanish versions of the IOP-29, IOP-M, Structured Inventory of Malingered Symptomatology, and Rivermead Post Concussion Symptoms Questionnaire. Results: The IOP-29 discriminated well between clinical patients and instructed feigners, with an excellent classification accuracy for the recommended cutoff score (FDS ≥ .50; sensitivity = 87.10% for coached group and 89.09% for uncoached; specificity = 95.12%). The IOP-M also showed an excellent classification accuracy (cutoff ≤ 29; sensitivity = 87.27% for coached group and 93.55% for uncoached; specificity = 97.56%). Both instruments proved to be resistant to symptom information coaching and performance warnings. Conclusions: The results confirm that both of the IOP measures offer a similarly valid but different perspective compared to SIMS when assessing the credibility of symptoms of mTBI. The encouraging findings indicate that both tests are a valuable addition to the symptom validity practices of forensic professionals. Additional research in multiple contexts and with diverse conditions is warranted.

Keywords:

• Feigning & malingering
• IOP-29 & IOP-M
• SVT & PVT
• symptom validity
• experimental malingering

Acknowledgments

We would like to thank Luciano Giromini for providing us with all the information and materials necessary to successfully execute this study.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

Since the database contains sensitive information on symptom validity tests, and its dissemination and knowledge may significantly undermine its effectiveness, an adapted version has been created for its dissemination. This database can be requested from the corresponding author ([email protected]).

Additional information

Funding

This study was funded by the Cathedra MAZ from the Universidad de Zaragoza. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. This research was supported in part by the Salisbury VA Health Care System and Mid-Atlantic (VISN 6) Mental Illness Research, Education, and Clinical Center (MIRECC). The views, opinions, and/or findings contained in this article are those of the authors and should not be construed as an official Veterans Affairs position, policy, or decision, unless so designated by other official documentation.