[Assessment of complex PTSD - internal and external validity of a diagnostic interview]

The diagnostic construct of complex posttraumatic stress disorder (complex PTSD) describes the consequences of early onset and long-term persisting psychological traumatizations. The interview for complex PTSD (I-kPTBS) - is the German adaptation of the structured interview for disorders of extreme stress (SIDES). The present study reports first data regarding the internal validity of the I-kPTBS as well as on the external validity of the diagnosis of complex PTSD.

The I-kPTBS was applied in 72 consecutive patients of a specialized outpatient clinic. 31 patients fulfilled the criteria of the diagnosis complex PTSD. 25 suffered from a PTSD but did not fulfil the diagnostic criteria of complex PTSD. Both groups where compared regarding their symptoms, resources and reports of childhood events.

Internal consistence of the I-kPTBS regarding the sample was good to excellent (alpha = 0.88). As expected, patients with the diagnosis of complex PTSD showed more severe dissociative, depressive and general anxiety symptoms than patients with PTSD alone. Patients fulfilling the criteria of complex PTSD reported a lower age at their first traumatic event, more multiple traumatizations and more often a dissociative disorder as comorbid diagnosis. Patients with complex PTSD show a higher traumaload in childhood and a lower level of compensatory resources.

The interview for complex PTSD (I-kPTBS) describes a consistent diagnostic construct. The results demonstrate that the diagnosis of complex PTSD selects a specific group of patients with early childhood trauma and high symptom level. Specific criteria can differentiate this patient group well from patients that suffer from PTSD alone.