The Impact of Event Scale (IES).
The Impact of Event Scale (IES) was developed to measure current subjective distress related to a specific life event (Horowitz et al 1979). Two response states are reported to be associated with psychological reactions to stress--avoidance and intrusion (Drottning et al 1995). The IES has 15 items, seven of which measure intrusive symptoms such as thoughts, nightmares, feelings, and images associated with the specific event. Five of these items reflect intrusive symptoms whilst awake and two reflect intrusion during sleep (nightmares, insomnia). The avoidance subscale has eight items such as numbing of responsiveness, and avoidance of feelings and situations. The intrusion and avoidance components are combined to produce a total score (Horowitz et al 1979). The IES does not include a hyperarousal subscale, the third major symptom cluster of posttraumatic stress, and in view of this a revised version of the scale was developed (IES-R) (Weiss and Marmar 1997) but this version is more difficult to interpret with no cut-off scores available.
The IES is free and available from the Victims' Web site at Swinburne University and in the NSW Motor Accident Authority Guidelines for the Management of Acute Whiplash.
Instructions to the client and scoring: The questionnaires take 5-10 minutes to complete and score, and requires no special training to administer. Respondents are asked to rate the frequency on a 4-point scale with which each symptom has occurred over the last week. The 4 points are: 0 (not at all), 1 (rarely), 3 (sometimes), and 5 (often). Scores range from 0 to 35 for intrusion, 0 to 40 for avoidance, and 0 to 75 for the total score. The total score can be interpreted according to the following dimensions of post-traumatic stress symptoms: 0 to 8 (subclinical range), 9 to 25 (mild range), 26 to 43 (moderate range), 44+ (severe range). It is suggested that the cut-off point is 26, above which a moderate or severe impact is indicated.
Reliability, validity and sensitivity to change: Test-retest reliability (r = 0.79 to 0.89) and internal consistency (Cronbach's ??= 0.78 to 0.82) has been demonstrated to be satisfactory (Horowitz et al 1979, Joseph 2000). The IES was originally devised as a measure of subjective distress and is a valid measure of such (Joseph 2000). However its content validity is severely limited as a measure of posttraumatic stress disorder and alternative instruments should be used if this condition is suspected (Joseph 2000). In other words, there is evidence supporting the use of the IES as a measure of trauma-related distress, although a diagnosis of PTSD cannot be made on the IES alone (Joseph 2000). The IES has been shown to be sensitive to detecting changes in clinical status over time (Corcoran and Fischer 1994).
The IES has been used widely to investigate trauma-related distress following whiplash injury (Sterling et al 2005), other injuries following road traffic accidents (Stallard and Smith 2007), war veterans and following natural disasters (Joseph 2000), as well as survivors of intensive care admission (Richmond and Kauder 2005), and following breast cancer diagnosis (Koopman et al 2005). There is some evidence to suggest that in the case of whiplash injury, trauma-related stress symptoms (IES scores) were superior predictors of persistent pain and disability when compared to general psychological distress and fear avoidance beliefs (Sterling et al 2005).
Physiotherapists are often involved in the management of people following traumatic events. In some cases, the physiotherapist may be the first health care provider to see the patient, for example whiplash injury following a motor vehicle crash. Physiotherapists may be more familiar with using psychological questionnaires that relate to pain and/ or disability and it should be noted that the IES measures distress related to an event (eg, accident, motor vehicle crash) rather than reported pain per se. This is an important point to note when administering the questionnaire. A cutoff score of 26 or above on the IES would be grounds for psychological referral. However referral may be deferred in the first few weeks after injury in order to allow natural recovery to occur (Forbes et al 2007). The physiotherapist's role in this regard would be to monitor symptoms with the IES and instigate referral if trauma symptoms persist. The optimal time frame for referral is debated but current guidelines suggest that trauma-related symptoms should be present for at least two weeks before trauma-focussed treatment is provided (Forbes et al 2007).
The University of Queensland, Australia
Corcoran K, Fischer J (1994) Measures for clinical practice: a sourcebook. Vol. 2. New York: The Free Press.
Drottning M et al (1995) Nordic Journal of Psychiatry 49: 293-299.
Forbes D et al (2007) ANZ Journal of Psychiatry 41: 637-648.
Horowitz M et al (1979) Psychosom Med 41: 209-218.
Joseph S (2000) J Trauma Stress 13: 101-113.
Koopman C et al (2002) J Trauma Stress 15: 277-287.
Richmond T, Kauder D (2005) J Trauma Stress 13: 681-692.
Stallard P, Smith E (2007) J Child Psychol 48: 194-201.
Sterling M et al (2005) Pain 114: 141-148.
Weiss D, Marmar C (1997) In: J Wilson and T Keane (Eds) Assessing Psychological Trauma and PTSD. New York: Guilford Press, 98-135.
Swinburne University http://www.swin.edu.au/victims/resources/assessment/ ptsd/ies.html
NSW Motor Accident Authority http://www.maa.nsw.gov.au/default.aspx?MenuID=95#415
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|Title Annotation:||Appraisal: Clinimetrics|
|Publication:||Australian Journal of Physiotherapy|
|Date:||Mar 1, 2008|
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