PSYCHOMETRIC CHARACTERISTICS OF THE SOMATOFORM DISSOCIATION QUESTIONNAIRE - A REPLICATION STUDY

Background: The present study aimed to replicate the results of previo us studies concerning the development of two versions of the Somatofor m Dissociation Questionnaire. The SDQ-20 evaluates the severity of som atoform dissociative phenomena, and the SDQ-5 is a dissociative disord ers screening instrument. Methods: Thirty-one patients with dissociati ve disorders and 45 consecutive psychiatric outpatients with other DSM -IV diagnoses completed the SDQ-20 and SDQ-5 as well as the Dissociati on Questionnaire which measures psychological dissociation. Results: M okken scale analysis showed that the items of the SDQ-20 are strongly scalable on a latent unidimensional scale. Internal consistency was hi gh. The SDQ-20 convergent validity was supported by high intercorrelat ions with the DIS-Q. Dissociative patients obtained significantly high er scores than comparison patients. Patients with dissociative identit y disorder scored significantly higher compared to patients with disso ciative disorder nos. Sensitivity (94%) and specificity (98%) of the S DQ-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%). Conclusion s: All results replicated the first findings, and therefore corroborat e the conclusion that the SDQ-20 and SDQ-5 are instruments of sound ps ychometric quality, and that somatoform dissociative phenomena are cor e symptoms of complex dissociative disorders.