Clinical Utility of Impact of Event Scale–Revised for Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition Posttraumatic Stress Disorder

Objective The Impact of Event Scale–Revised (IES-R) is a widely used self-report for assessing posttraumatic stress disorder (PTSD), originally aligned with Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV diagnostic criteria. This study aimed to evalu-ate the applicability of the IES-R under the DSM-5 guidelines and establish a cutoff point for DSM-5 PTSD diagnosis. Methods A total of 238 participants recruited from multiple psychiatric centers, including 67 patients with PTSD, 72 patients with psy-chiatric controls, and 99 healthy controls, were included in the study. All participants completed the Korean version of the Structured Clini-cal Interview for the DSM-5 research version to confirm the presence of PTSD, the Korean version of PTSD Checklist for DSM-5 (PCL-5), the Beck Depression Inventory-II, the Beck Anxiety Inventory, and the Spielberger State Trait Anxiety Inventory. Results The IES-R demonstrated good internal consistency and a high correlation with the PCL-5. Through factor analysis, 5 distinct dimensions emerged within the IES-R: sleep disturbance, intrusion, hyperarousal, avoidance, and numbness-dissociation. A proposed cutoff score of 25 on the IES-R was suggested for identifying patients with PTSD. Conclusion These findings underscore the scale’s concurrent validity with the DSM-5 PTSD criteria and its effectiveness as a screening tool. Implementing a cutoff score of 25 on the IES-R can enhance its utility in identifying DSM-5 PTSD cases.