The International Trauma Questionnaire (ITQ) is a well-validated measure of ICD-11 PTSD and CPTSD. However, further validation is needed in other samples and using external correlates representing a broader range of psychopathology.

We first examined the internal consistency of the ITQ, and then examined its convergent and discriminant validity with a wide variety of external correlates, including PTSD, childhood trauma, dissociation, somatization, anxiety, anxiety related disorders, depression, mania, paranoia, schizophrenia, borderline features, antisocial features, drug use, alcohol use, aggression, suicidal ideation, stress, interpersonal functioning, and treatment rejection.

Using data from a trauma-exposed sample of college students (N = 246), we evaluated internal consistency via Cronbach's alpha and MacDonalad's omega, and convergent and discriminant validity via Pearson correlations and follow-up z tests using the Meng-Rosenthal-Rubin (1992) procedure to assess differences between the PTSD and DSO scales of the ITQ.

The ITQ has strong internal consistency reliability as indicated by Cronbach's alpha and MacDonald's omega. Patterns of convergent and discriminant validity fell broadly in hypothesized patterns, supporting the distinction between ICD-11 PTSD and CPTSD. All significant contrast analyses showed that correlations with external criterion variables were greater for ITQ DSO as compared to ITQ PTSD.

Our results indicate that the ITQ is a psychometrically sound measure of ICD-11 PTSD and CPTSD. As indicated by the differential pattern in convergent and discriminant validity with a broad range of external correlates, the scale readily distinguishes PTSD and DSO as distinct constructs.