Author(s): Nijenhuis ER, Spinhoven P, van Dyck R, van der Hart O, Vanderlinden J
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Abstract BACKGROUND: The present study aimed to replicate the results of previous studies concerning the development of two versions of the Somatoform Dissociation Questionnaire. The SDQ-20 evaluates the severity of somatoform dissociative phenomena, and the SDQ-5 is a dissociative disorders screening instrument. METHODS: Thirty-one patients with dissociative disorders and 45 consecutive psychiatric outpatients with other DSM-IV diagnoses completed the SDQ-20 and SDQ-5 as well as the Dissociation Questionnaire which measures psychological dissociation. RESULTS: Mokken scale analysis showed that the items of the SDQ-20 are strongly scalable on a latent unidimensional scale. Internal consistency was high. The SDQ-20 convergent validity was supported by high intercorrelations with the DIS-Q. Dissociative patients obtained significantly higher scores than comparison patients. Patients with dissociative identity disorder scored significantly higher compared to patients with dissociative disorder nos. Sensitivity (94\%) and specificity (98\%) of the SDQ-5 were very satisfactory, as were, at an estimated prevalence rate of dissociative disorders of 10\% among psychiatric patients, positive predictive value (84\%) and negative predictive value (99\%). CONCLUSIONS: All results replicated the first findings, and therefore corroborate the conclusion that the SDQ-20 and SDQ-5 are instruments of sound psychometric quality, and that somatoform dissociative phenomena are core symptoms of complex dissociative disorders.
This article was published in Psychother Psychosom
and referenced in Journal of Psychology & Psychotherapy