Impact of Event Scale-6 (IES-6) for U.S. Adults Who Experienced the COVID-19 Pandemic

Background: Post-traumatic stress disorder (PTSD) is a mental illness caused by traumatic events, such as the COVID-19 pandemic. Accurate diagnosis of this disorder is critical to establish effective intervention approaches. The Impact of Event Scale-6 (IES-6) is widely used for PTSD screening, but there has been no research on its psychometric properties with individuals who experienced the COVID-19 pandemic. Methods: : A random sample of 600 participants were randomly selected from a COVID-19 survey database ( n = 6,391). Rasch analysis was conducted to examine item fit, rating scale structure, construct validity, differential item functioning (DIF), and precision of the IES-6. Results: : The principal component analysis of Rasch residuals (54.1% of the raw variance explained) and the average of residual correlations (average r = .19) supported the unidimensionality structure in the IES-6. The rating scale was suitable, and the item difficulty hierarchy was logical. The item fit and the DIF contrast were acceptable, except for item 5. The IES-6’s person reliability was .76, which was also an acceptable level. Conclusions: : This study showed that the IES-6 has acceptable item-level psychometrics for screening PTSD in adults in the United States for individuals who have experienced the COVID-19 pandemic. The findings suggested that the IES-6 would be useful for the rapid identification of PTSD and allow clinicians to quickly provide interventions for people with the disorder and their families.