The Impact of Event Scale - Revised (IES-R)

Issue #19 of General Assessment Series

WHY: Post-traumatic stress disorder (PTSD) is the development of characteristic symptoms after exposure to one or more traumatic events. The presentation varies, but may include fear-based re-experiencing, emotional and behavioral changes, dysphoric moods, or negative cognitions (APA, 2013). The latest data estimates that the lifetime prevalence rate for PTSD is up to 4.5% of community living older adults (Cook et al. 2017). Along with PTSD, age-related changes, and associated disease processes, stress reaction in older adults may lead to a deterioration of function and a worsening of existing conditions. Therefore, older adults should be considered a high-risk group following a disaster or specific traumatic event, including a catastrophic medical illness (Moye & Rouse, 2014). Several factors in adapting to a disaster have been recognized as important in the older adult: an increased sense of insecurity and vulnerability; a loss of sense of control and predictability; a need to reaffirm familiar relationships, attachments and routines; and to remain independent. The impact of a disaster on older adults can be magnified by chronic illness and medication, sensory limitations, mobility impairment, and literacy that place the older adult in the special needs population after a traumatic event. Older adults who develop PTSD also have higher rates of chronic disease and higher rates of disability (Cook et al., 2017 & Pietrzak et al., 2012). For all of these reasons it is important to evaluate an older adult’s response to trauma and monitor the effects of time.

BEST TOOL: A short, easily administered self-report questionnaire, the Impact of Event Scale – Revised (IES-R), has 22 questions, 5 of which were added to the original Horowitz (IES) to better capture the American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria for PTSD (Weiss & Marmar, 1997). The tool, not diagnostic for PTSD, is an appropriate instrument to measure the subjective response to a specific traumatic event in the older adult population, especially in the response sets of intrusion (intrusive thoughts, nightmares, intrusive feelings and imagery, dissociative-like re-experiencing), avoidance (numbing of responsiveness, avoidance of feelings, situations, and ideas), and hyperarousal (anger, irritability, hypervigilance, difficulty concentrating, heightened startle), as well as a total subjective stress IES-R score. The IES-R is not meant to be diagnostic. While there is no specific cut-off score, scores higher than 24 are of concern; the higher the score the greater the concern for PTSD and associated health and well-being consequences. The IES-R revises the original IES, recognized as one of the earliest self-report tools developed to assess for post-traumatic stress, to add a third cluster of symptoms, hyperarousal, to intrusion and avoidance subscales. IES-R is the acronym for the test assessment purpose:

I – Impact 
E – of Event 
S – Scale
R – Revised

TARGET POPULATION: The IES-R can be used with both healthy and frail older adults exposed to any specific traumatic event. It can be used for repeated measurements over time to monitor progress.

VALIDITY AND RELIABILITY: The IES-R was designed and validated using a specific traumatic event as a reference in the directions to the individual while administering the tool and while using a specific time frame of the past seven days. The scale discriminates between different types of traumatized groups from non-traumatized groups in general population studies. The subscales of avoidance and intrusion show good internal consistency. While related, the subscales measure different dimensions of stress response. African Americans have been shown to score higher than whites on the IES in general population studies, an effect that diminished with increasing relative violence, and this should be taken into account during interpretation. The hyperarousal sub-scale added by Weiss and Marmar has good predictive validity with regard to trauma (Briere, 1997), while the intrusion and avoidance subscales detect relevant differences in the clinical response to traumatic events of varying severity.

STRENGTHS AND LIMITATIONS: The main strengths of this revised instrument are that it is short, easily administered and scored, it correlates better with the DSM Criteria for PTSD, and can be used repeatedly to assess progress. It is limited by its role as a screening tool rather than a comprehensive test and by the non-clinical focus. It is best used for recent, not remote, traumatic events. The IES-R has been translated into many languages including Spanish, French, Chinese, Japanese, and German.


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Weiss, D.S., & Marmar, C.R. (1997). The Impact of Event Scale-Revised.  In J.P. Wilson, & T.M. Keane (Eds.), Assessing Psychological Trauma and PTSD:  A Practitioner’s Handbook (pp. 399-411).  New York:  Guilford Press.

Weiss, D.S. (2004). The Impact of Event Scale-Revised. In J.P. Wilson, & T.M. Keane (Eds.), Assessing psychological trauma and PTSD: A practitioner’s handbook (2nd ed., pp. 168-189). New York: Guilford Press.

Weiss, D.S. (2007). The Impact of Event Scale: Revised. In J.P. Wilson, & C.S. Tang (Eds.), Cross-cultural assessment of psychological trauma and PTSD (pp. 219-238). New York: Springer.

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