The Impact of Event Scale - Revised: psychometric properties of the Italian version in a sample of flood victims

Background: This study aims to verify the main psychometric properties of the Italian version of the Impact of Event Scale - Revised (IES-R) in a sample of flood victims. Methods: The sample was composed of 262 subjects involved in the natural disaster of 2009 in the city of Messina (Italy). All participants completed the IES-R and the Dissociative Experiences Scale-II (DES-II) in order to verify some aspects of convergent validity. Results: The exploratory and confirmatory factor analysis, used to verify the construct validity of the measure, showed a clear factor structure with three independent dimensions: intrusion, avoidance, and hyper-arousal. The goodness-of-fit indices (non-normed fit index [NNFI] = 0.99; comparative fit index [CFI] = 0.99; standardized root mean square residual [SRMR] = 0.04; and root mean square error of approximation [RMSEA] = 0.02) indicated a good adaptation of the model to the data. The IES-R scales showed satisfactory values of internal consistency (intrusion, alpha = 0.78; avoidance, alpha = 0.72; hyper-arousal, alpha = 0.83) and acceptable values of correlation with the DES-II. Conclusion: These results suggest that this self-reported and easily administered instrument for assessing the dimensions of trauma has good psychometric properties and can be adopted usefully, both for research and for practice in Italy.