Factor Analysis and Measurement Invariance of the PTSD Subscale in the International Trauma Questionnaire

Assessing the psychological impact of trauma is crucial for understanding and addressing its multifaceted consequences, such as Post-Traumatic Stress Disorder (PTSD) and Complex Post-Traumatic Stress Disorder (CPTSD). The International Trauma Questionnaire (ITQ) is a promising tool designed to evaluate and quantify the effects of traumatic experiences. The ITQ has gained significant attention and implementation in clinical practice and psychotraumatology studies due to its parsimony and comprehensible construct structure grounded in the definition of PTSD and CPTSD as present in the 11th version of the International Classification of Diseases (WHO, 2019). The availability of both the original and translated versions of the ITQ has allowed for further research, which has generally confirmed the validity and reliability of the scale in different populations. In previously published papers, the emphasis was placed on the construct validation of the scale. Establishing construct validity is necessary for administering the tool to different groups and populations, as well as for the general replicability of the research. This paper aims to scrutinize the construct validity of ITQ’s PTSD subscale by examining the robustness of its factorial structure and its measurement (factorial) invariance across the first and second waves of the COVID-19 pandemic in Italy. The present work creates continuity with previously conducted research by evaluating the latent factorial structure of the PTSD construct. In addition, it extends the pool of evidence for the ITQ’s construct validity by confirming the longitudinal measurement invariance of the PTSD subscale.