Assessing the reliability and validity of the International Trauma Interview in a sample of Ukrainian soldiers

Background
The International Trauma Interview (ITI) is a clinical interview used to diagnose ICD-11 posttraumatic stress disorder (PTSD) and complex PTSD (CPTSD). Six studies have assessed the latent structure of the ITI and have generally advocated for models consistent with the ICD-11 description of PTSD and CPTSD, despite the common occurrence of improper solutions. Diagnostic concordance between the ITI and a self-report measure–International Trauma Questionnaire (ITQ)–has also been low. Here, the latent structure of the ITI was examined, along with tests of internal reliability, concurrent/discriminant validity, and diagnostic concordance between the ITI and ITQ.
Methods
Data were collected from 209 combat-exposed, active-duty Ukrainian soldiers. Confirmatory factor analysis was used to test seven latent structural models of the ITI. Structural equation modelling was used to test concurrent/discriminant validity.
Results
The two models consistent with the ICD-11 formulation of PTSD and CPTSD either had unsatisfactory fit or contained out-of-bounds parameter estimates. The latent structure of the ITI items was best explained by a correlated two-factor model representing PTSD and DSO symptoms. The PTSD and DSO scores had good internal reliability, and were correlated with depression, anxiety, insomnia, and psychological wellbeing. Diagnostic concordance between the ITI and ITQ was ‘moderate’-to-‘substantial’.
Conclusion
The latent structure of the ITI in this sample was not consistent with the formulation of ICD-11 PTSD and CPTSD. The implications of the ITI not measuring the different symptom clusters of these disorders are discussed.