Self-reported versus clinician-evaluated symptom assessment and diagnosis of ICD-11 PTSD and CPTSD: a comparison between the International Trauma Interview and the International Trauma Questionnaire

<b>Background:</b> The ICD-11 introduced distinct criteria for Posttraumatic Stress Disorder (PTSD) and Complex PTSD (CPTSD), necessitating validated assessment tools. While the International Trauma Questionnaire (ITQ) is a widely used self-report measure, the International Trauma Interview (ITI) is a structured clinician-administered interview considered a gold standard. This study investigated the correspondence between ITQ and ITI symptom and diagnostic classifications in a treatment-seeking veteran population.<b>Methods:</b> A sample of 108 Danish veterans completed both the ITQ and ITI. We calculated descriptive statistics, bivariate correlations, and Cohen's <i>κ</i> values to assess agreement for individual symptom items and diagnostic categories (ICD-11 PTSD, CPTSD, and PTSD or CPTSD combined), using the ITI as the reference standard. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were also determined.<b>Results:</b> ITQ scores were consistently higher than ITI scores across all symptom domains. Total symptom scores for PTSD, DSO, and CPTSD showed strong associations between instruments (<i>r</i> = .74 to .82, all <i>p</i> < .001). Agreement for individual symptom items varied from fair to substantial (<i>κ</i> = .33 to .70). The combined diagnosis of PTSD or CPTSD showed moderate agreement (<i>κ</i> = .60) with high sensitivity (0.94) and PPV (0.90). However, agreement for ICD-11 PTSD alone was fair (<i>κ</i> = .38), with low PPV (0.39) despite good sensitivity (0.65).<b>Conclusion:</b> The ITQ consistently reported higher symptom endorsement than the ITI. While the ITQ shows strong convergent validity for overall symptom burden and high sensitivity for screening trauma-related psychopathology (PTSD or CPTSD combined), its limited agreement for standalone ICD-11 PTSD diagnosis suggests it should not be used as a sole diagnostic tool. Comprehensive clinical interviews remain crucial for definitive diagnosis, while the ITQ can serve as an effective screening instrument.