Assessing Prevalence, Validity, and Correlates of ICD-11 Posttraumatic Stress Disorder and Complex Posttraumatic Stress Disorder in Ireland

Background: The most frequently used measure of the 11th edition of the International Classification of Diseases (ICD-11) complex posttraumatic stress disorder (CPTSD) is the International Trauma Questionnaire (ITQ). While there is strong support for the psychometric properties of the ITQ, few studies have assessed its reliability and validity in nationally representative samples. Additionally, several correlates of ICD-11 CPTSD have been identified; however, few studies have assessed multiple correlates simultaneously. Objective: To assess the factorial validity and internal reliability of the ITQ in a nationally representative sample of adults living in Ireland (N = 1,100); determine the prevalence rates of ICD-11 posttraumatic stress disorder (PTSD) and CPTSD; and identify correlates of CPTSD symptoms and how CPTSD symptoms relate to risk of suicide. Method: Confirmatory factor analysis was performed to evaluate the factorial validity of the ITQ, and structural equation modeling (SEM) was used to determine the unique multivariate associations between 10 predictor variables (age, sex, urban dwelling, unemployment status, number of traumatic events, COVID-19 infection, knowing someone who died from COVID-19, loneliness, social support, and sleep problems) and symptoms of CPTSD, and the unique associations between CPTSD symptoms and suicide risk. Results: The ITQ produces reliable and valid scores, 11.2% of people met requirements for ICD-11 PTSD (2.4%) or CPTSD (8.8%), exposure to a higher number of traumatic life events, higher levels of loneliness, and more sleep problems predicted CPTSD symptoms; and negative self-concept (NSC) symptoms were most strongly associated with suicidality. Conclusions: Where the risk of suicide is high, treating symptoms of NSC, loneliness, and sleep problems may be advisable. Clinical Impact Statement Our study demonstrates that approximately 11% of adults living in Ireland meet diagnostic requirements for the 11th edition of the International Classification of Diseases (ICD-11) posttraumatic stress disorder (PTSD) or complex posttraumatic stress disorder (CPTSD). Findings show that exposure to a higher number of traumatic life events, higher levels of loneliness, and more sleep problems are important correlates of CPTSD symptoms. Of all the CPTSD symptoms, negative self-concept (NSC) symptoms are the most important in understanding the risk of suicide. We have recommended that in situations where clinicians believe that th