“…The UCLA PTSD-RI is a 27-item scale, covering the four diagnostic criteria in the fifth edition of the DSM-5 (American Psychiatric Association, 2013). In the Utøya Study, four items measuring criteria D2 and E2 were combined into two, and PTSD reactions were measured by 25 items (Undset et al, 2024). Each question in the UCLA PTSD-RI was explicitly related to the attack, and responses were endorsed on a 5-point scale, ranging from 0 ( never ) to 4 ( almost all the time ).…”