It is commonly used in research and clinical settings to measure the severity of symptoms related to post-traumatic stress disorder (PTSD).
The IES-R is an updated version of the original Impact of Event Scale (IES) and includes additional items to provide a more comprehensive assessment.The 15-item IES is the original scale, but is missing the symptom of hyperarousal.
The IES-R contains seven additional items related to the hyperarousal symptoms of PTSD, which were not included in the original IES.
[1] Respondents are asked to identify a specific stressful life event and then indicate how much they were distressed or bothered during the past seven days by each "difficulty" listed.
However, cut-off scores for a preliminary diagnosis of PTSD have been cited in the literature.