Abstract
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 evaluate 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 psychiatric controls, and 99 healthy controls, were included in the study. All participants completed the Korean version of the Structured Clinical 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.