Longitudinal Invariance and Validity of the Impact of Event Scale-Revised Under COVID-19 Pandemic in a Brazilian Sample

Although the Impact Event Scale-Revised is widely used, its factor structure is still controversial. In addition, its longitudinal measurement invariance (LMI) remains uninvestigated. In this sense, we carried out three studies to investigate its psychometric properties. In Study 1, we evaluated the factorial structure of the scale comparing the different models existing in the literature in Brazilian samples who responded to the instrument during the COVID-19 pandemic. In Study 2, we provide support for a five-factor model throughout convergent validity with psychological distress and sleep problems, and criterion validity between people with diagnostic of mental disorders. Finally, we evaluated the LMI over a 6-month interval. The results indicated that the five-factor model has excellent goodness of fit and holds strict longitudinal invariance. Additionally, internal consistency and stability coefficients indicate that the scale is appropriate to measure posttraumatic stress symptomatology) in nonclinical samples across multiple assessments. Public Significance Statement This study compared different factor structures for the Impact of Event Scale-Revised (IES-R). Findings support a five-factor model to explain posttraumatic stress symptoms. In addition, IES-R holds for longitudinal measurement invariance, and it is related to psychopathology indicators, worsening quality of life, and sleep difficulties. The scale is widely used in research and can contribute to clinical assessment.

Automated summary

This study investigates the factor structure and longitudinal measurement invariance of the Impact Event Scale-Revised (IES-R). The findings support a five-factor model to explain posttraumatic stress symptoms. The IES-R demonstrates good fit and holds strict longitudinal invariance. It is also related to psychopathology indicators, worsening quality of life, and sleep difficulties.