Clinical Validation of the Italian Multidimensional Inventory of Dissociation (I-MID)

The aim of the present study was to verify the reliability and validity of the Italian Multidimensional Inventory of Dissociation (I-MID) when applied to a clinical sample. The I-MID was administered to 100 outpatients presenting to a south-Italian public psychology service for psychotherapeutic treatment. Both self-report and interview-based methods were used to assess traumatic experiences and dissociative symptoms. The Dissociative Disorders Interview Schedule DSM-5 Version (DDIS-5) was utilized to identify dissociative disorders and psychiatric diagnoses commonly associated with dissociative and symptoms and disorders. The I-MID showed strong internal consistency, structural, convergent, and construct validity. Results addressing temporal stability were good for the MID mean score, but results for the different scales were more variable across time. Discriminant validity was good, but some limitations imposed by the clinical sample prevented a sound evaluation of this test property. Information about construct and discriminant validity for the Italian versions of the Dissociative Experiences Scale-II (DES-II) and the Dissociative Symptom Scale (DSS) is also provided. All instruments exhibited good psychometric properties. However, the I-MID showed better incremental validity compared to the DES-II, and provided some evidence of enhanced discriminant validity relative to both the DES-II and DSS. The findings of this study support the validity of the MID and its underlying subjective-phenomenological model of dissociation in an Italian clinical sample. Finally, the prevalence of dissociative disorders in our outpatient sample aligned with findings from other countries' epidemiological studies.