We examined the impact of demographic confounding factors on responses to the Impact of Event Scale–Revised.

Participants were rescue workers aged 20 to 65 years who had responded during the Great East Japan Earthquake in 2011. A multiple indicators, multiple causes model was used to examine associations between covariates and latent factors or items in the Impact of Event Scale–Revised.

Participants were recruited from April to August 2015. The model fit indices in the confirmatory factor analysis and the multiple indicators, multiple causes model suggested an acceptable model fit. Higher education and the Connor-Davidson Resilience Scale score were significantly associated with a decrease in intrusion, avoidance, and hyperarousal. Counseling was significantly associated with increased avoidance. In the direct path model using modification indices, counseling and early arrival were identified as significant covariates.

This study found that higher education and resilience reduced all 3 factors in the Impact of Event Scale–Revised and improved the symptoms of intrusion, avoidance, and hyperarousal. Counseling and early arrival were also associated with improvement in certain items. However, counseling was also linked to increased avoidance and worsening psychophysiological reactions. Further research is recommended to clarify these relationships. (Disaster Med Public Health Preparedness. 2019;13:309–318)