International Trauma Questionnaire with ‘clinical checks’ (ITQ-CC): measuring PTSD and complex PTSD in a population-based study in Poland

Background: The International Trauma Questionnaire (ITQ) is a widely used measure of ICD-11 Posttraumatic Stress Disorder (PTSD) and Complex PTSD (CPTSD), enabling the estimation of the prevalence rates of these disorders in general population and clinical samples. Due to concerns related to the use of self-report measures, authors of the original version introduced the concept of ‘clinical checks’, which are added in the new version to ensure initial responses reflected the intended clinical meaning of the scale items.Objective: As the concept is new and needs testing in different cultural settings, the aim of this study was to measure and compare the prevalence of probable PTSD and CPTSD in a representative sample of Poles with the use of a new version of the ITQ (ITQ-CC) and an original one.Method: We collected data from a representative sample of adults from Poland (N = 1,816) via an internet research panel.Results: Comparison of the results obtained with the use of ITQ versus ITQ-CC revealed that individual symptom endorsements decreased by between 18.9% and 41.6%. Disorder prevalence estimates without the clinical checks were 5.3% for PTSD and 6.1% for CPTSD. These estimates dropped to 2.4% for PTSD, and to 3.5% for CPTSD, when the clinical checks were used; thus the relative decrease was 55.7% for PTSD, and 48.7% for CPTSD, giving a total relative reduction rate of 48.8%.Conclusion: The study results indicate a significant influence of clinical checks on post-traumatic symptoms screening. This resulted in a substantial reduction in the estimated PTSD and CPTSD prevalence rates.