Are DSM-5 and ICD-11 posttraumatic stress disorder measures assessing the same construct? Evidence from a Rasch-based...

This study examined whether DSM-5 and ICD-11 self-report operationalizations of posttraumatic stress disorder (PTSD) are psychometrically equivalent. Using Rasch modeling, we compared the psychometric properties and convergent validity of the PTSD Checklist for DSM-5 (PCL-5) and the International Trauma Questionnaire (ITQ) in a sample of 483 Syrian refugees residing in Türkiye (63.9% women, M_age = 31.60 years, SD = 11.48). Both instruments demonstrated acceptable model fit and reliability. However, the PCL-5, r = .792, showed significantly stronger associations with depression than the ITQ, r = .691, p < .001, whereas associations with anxiety were comparable. Probable PTSD prevalence was higher using DSM-5 criteria (26.9%) than ICD-11 criteria (21.9%). A proxy score comprising PCL-5 items mapped onto ICD-11 symptom clusters also correlated more strongly, r = .790, withdepression than the ITQ, r = .701, suggesting that differences in item content rather than item count drive the observed pattern. These findings indicate that the PCL-5 and ITQ are not psychometrically equivalent. The PCL-5 appears to capture a broader internalizing distress syndrome, whereas the ITQ provides a more parsimonious assessment of trauma-specific symptoms. The results are specific to self-report operationalizations and cannot be generalized to clinician-administered diagnoses. The choice of assessment instrument may, therefore, meaningfully influence prevalence estimates, comorbidity patterns, and the interpretation of PTSD in trauma-exposed populations.