Validation of ICD-11 PTSD and DSO using the International Trauma Questionnaire in five clinical samples recruited in Denmark

Background: The 11 ^th version of the International Classification of Diseases (ICD-11) revised the diagnosis of Posttraumatic Stress Disorder (PTSD) and introduced Complex PTSD as a sibling disorder to PTSD. As the Danish Health Authorities will implement the ICD-11 in 2022, it is more relevant than ever to introduce a measure that enables the identification of ICD-11 PTSD and CPTSD. Objective: The primary aim of the present study was to test the construct validity of the ICD-11 conceptualization of PTSD and DSO in five clinical samples using translated versions of the International Trauma Questionnaire (ITQ). Method: Data from existing studies of adult survivors of sexual abuse (n = 385), women in shelters (n = 147), psychiatric outpatients endorsing an ICD-10 diagnosis of PTSD (n = 111), a heterogenous sample of psychiatric outpatients (n = 178) and refugees and torture survivors (n = 385) was used for the current study. Confirmatory factor analyses were conducted to test the internal structure of the ITQ, and regression models were conducted to test the convergent and discriminant validity of the factor solutions for each sample. Results: Findings supported the ICD-11 formulation of PTSD and disorders in self-organization (DSO) as a representation of the latent structure of the ITQ across five Danish clinical samples. Uniquely for women in shelters, however, the model displayed an unacceptable fit. A revised operationalization of re-experiencing proved a better fit when ‘recurrent nightmares’ was exchanged with symptoms of intense emotional reactions to reminders of the trauma for women in shelter as well as ICD-10 PTSD psychiatric outpatients. Conclusion: This study supports the use of a Danish translated version of the ITQ to assess symptoms of ICD-11 PTSD and DSO for the introduction of ICD-11 in 2022. Future research is needed to further explore the operationalization of re-experiencing across different trauma exposed populations.