Reliability and validity of the Korean version of the Impact of Event Scale-Revised

Objectives: The aim of this study was to explore the reliability and validity of the Impact of Event Scale-Revised Korean version (IES-R-K), a self-report scale for assessment of posttraumatic stress disorder (PTSD). Methods: The original Impact of Event Scale-Revised was translated into Korean, and the comparability of content was verified through back-translation procedures. This multicenter study included 9 3 patients with PTSD, 7 3 nonpsychotic psychiatric patients. and 88 healthy controls drawn from 18 hospitals across the country. The subjects were assessed using [ES-R-K, Clinician-Administercd PTSD Scale (CAPS), Beck Depression Inventory, and State Trait Anxiety Inventory (STAI; state anxiety subscale [STAI-S], trait anxiety subscale [STAI-T]) scales. Results: In the reliability test, Cronbach alpha coefficient and test-retest reliability were .93 and 0.91, respectively, indicating that the IES-R-K has good internal consistency. One-way analysis of variance revealed significant differences in IES-R-K scores among the patients with PTSD, nonpsychotic psychiatric patients, and healthy controls (F = 139.1, P <.001). Duncan post hoc test showed the significant differences among the 3 groups. To assess the validity of the IES-R-K, correlation coefficient between the IES-R-K and CAPS, STAI-S, and STAI-T was calculated. We found that there was a relatively high degree of correlation between the IES-R-K and CAPS (r = 0.92, P <.001). However, there was a relatively less degree of correlation between STAI-S and STAI-T and IES-R-K (r = 0.30, P <.001). Taken these together, IFS-R-K showed good discriminant validity. Conclusion: The IES-R-K showed good reliability and validity for the assessment of PTSD symptom severity. The IES-R-K is a useful instrument for assessing PTSD symptoms in Korea. Crown Copyright (C) 2009 Published by Elsevier Inc. All rights reserved.