Discriminant validity of the Structured Inventory of Malingered Symptomatology (SIMS) under conditions of simulating symptoms

Abstract

Background/Aim. The Structured Inventory of Malingered Symptomatology (SIMS) is a self-report measure to be used with adults, which may be utilized to assess the potential malingering of psychosis, neurologic impairment, amnesia, low intelligence, or affective disorder. The aim of the study was to examine the discriminant validity of SIMS under conditions of simulating symptoms of neurological and memory disorders, in response to a hypothetical situation, after watching a recording of an actual car accident in which a motorcycle rider sustained head injuries. Methods. The study involved 94 students (35 men and 59 women) from the University of Criminal Investigation and Police Studies in Belgrade and the Faculty of Medicine – Special Education and Rehabilitation in Novi Sad, aged 20–26 [arithmetic mean = 20.69; standard deviation (SD) = 0.80], divided into two groups (n = 47), malingerer and control. The malingerer group was instructed to identify with the motorcycle rider hit by the car and malinger symptoms related to neurological difficulties and amnesia in order to obtain greater reimbursement from the insurance company. The control group had instructions to honestly assess the probability of occurrence of the symptoms. Results. The results of the multivariate one-way analysis of variance suggested that the effect of experimental manipulation was statistically significant [F (88, 5) = 91.21, p < 0.001; η2p = 0.838]. Univariate effects were also statistically significant for all five scales. Participants in the malingerer group scored higher on all five scales than participants in the control group. The magnitudes of the effects support the largest differences between the malingerer and control groups on the scales of Memory Disorders and Neurological Disorders, which was also the basic instruction for simulating symptoms given to the participants in the malingerer group. Conclusion. The obtained results support the discriminant validity of the SIMS questionnaire in the situation of simulating symptoms of neurological disorders and memory disorders.

Uvod/Cilj. Strukturisani inventar simuliranih simptoma – Structured Inventory of Malingered Symptomatology (SIMS) je mera samoprocene koja se koristi kod odraslih osoba, a može biti korišćena za procenu potencijalnog razvoja psihoze, neurološkog oštećenja, amnezije, niske inteligencije ili afektivnog poremećaja. Cilj rada bio je da se ispita diskriminativna validnost SIMS-a u uslovima simuliranja simptoma neuroloških oštećenja i poremećaja pamćenja u odgovoru na hipotetičku situaciju, nakon gledanja snimka realne saobraćajne nezgode u kojoj je vozač motocikla zadobio povrede glave. Metode. U istraživanju su učestvovala 94 studenta (35 muškaraca i 59 žena) Kriminalističkopolicijskog univerziteta u Beogradu i Medicinskog fakulteta – smer Specijalna edukacija i rehabilitacija u Novom Sadu, starosti od 20–26 godina [aritmetička sredina = 20.69; standardna devijacija (SD) = 0.80)], koji su bili podeljeni u dve grupe (n = 47), kontrolnu grupu i grupu ispitanika koji su simulirali simptome. Grupa ispitanika koji su simulirali simptome imala je zadatak da se poistoveti sa motociklistom kojeg je udario automobil i da simulira neurološke simptome i amneziju, sa ciljem da dobiju više novca od osiguravajuće kompanije. Kontrolna grupa imala je zadatak da iskreno proceni koji simptomi bi mogli nastati nakon saobraćajne nesreće. Rezultati. Rezultati multivarijatne jednosmerne analize varijanse su pokazali da je efekat eksperimentalne manipulacije bio statistički značajan [F(88, 5) = 91.21, p < 0.001; η2p = 0.838]. Univarijatni efekti su takođe bili statistički značajni za svih pet skala. Ispitanici iz kontrolne grupe postizali su niže skorove na svih pet skala u odnosu na ispitanike iz grupe koja je simulirala simptome. Veličine efekata govore u prilog najvećih razlika između grupe koja je simulirala simptome i kontrolne grupe na skalama Poremećaji pamćenja i Neurološka oštećenja, što je ujedno i bila osnovna instrukcija za simuliranje simptoma kod te grupe ispitanika. Zaključak. Dobijeni rezultati idu u prilog diskriminativne validnosti upitnika SIMS u situaciji simuliranja simptoma neuroloških oštećenja i poremećaja pamćenja.