Edinburgh Napier University

  Background
ICD-11 complex posttraumatic stress disorder (CPTSD) is a more severe condition than PTSD, and recent studies indicate it is more prevalent among military samples. In this study, we tested the psychometric properties of the International Trauma Questionnaire (ITQ), assessed the relative prevalence rates of PTSD and CPTSD in the sample population, and explored relationships between CPTSD and PTSD and a range of risk-factors.

Methods
Survey participants (N = 189) were mental health support-seeking former-serving veterans of the Australian Defence Forces (ADF) recruited from primary care. Confirmatory factor analysis was used to test the factorial validity of the ITQ.

Results
The latent structure of the ITQ was best represented by a two-factor second-order model consistent with the ICD-11 model of CPTSD. The ITQ scale scores demonstrated excellent internal reliability. Overall, 9.1% (95% CI = 4.8%, 13.5%) met diagnostic requirements for PTSD and an additional 51.4% (95% CI = 44.0%, 58.9%) met requirements for CPTSD. Those meeting diagnostic requirements for CPTSD were more likely to have served in the military for 15 years or longer, had a history of more traumatic life events, and had the highest levels of depression, anxiety and stress symptoms.

Conclusion
The ITQ can effectively distinguish between PTSD and CPTSD within primary care samples of ADF veterans. A significantly greater proportion of ADF veterans met criteria for CPTSD than PTSD. Australian military mental health services should adopt the ITQ to routinely screen for CPTSD and develop CPTSD specific interventions to promote recovery in ADF veterans with CPTSD.