Psychometric evaluation of the Indonesian version of the Impact of Event Scale-Revised.

The purpose of this research was to translate and to test an Indonesian version of the Impact of Event Scale-Revised (I-IES-R) as a measurement of psychological distress following a natural disaster. Sample of 30 Mt. Merapi residents participated in pilot testing and 110 survivors completed the test-retest of the I-IES-R. Exploratory factor analysis was used to determine construct validity, and Cronbach's alpha was used to assess reliability. The results of the translational phase of the study indicated that the Indonesian version of the IES-R captures the content of the original tool with appropriate adaptation for cultural differences. The Indonesian IES-R revealed a Cronbach's alpha of 0.90 for test and 0.92 for retest for the total score. In addition, the Cronbach alpha for subscales intrusion, avoidance and hyper arousal in the initial scale testing were 0.85, 0.75, and 0.74, respectively, and for the retest 0.88, 0.79, and 0.82, respectively. The reliability coefficient of the test-retest results was 0.75 [95% confidence interval = (0.64, 0.83)], and exploratory factor analysis identified three underlying factors: intrusion, avoidance, and hyper arousal. The I-IES-R can be considered a useful screening tool that can be used by mental health nurses to assess the psychological impact of natural disasters on survivors in Indonesia.