Horowitz's Impact of Event Scale evaluation of 20 years of use

The main objective of this meta-analysis was to model the relations between a set of independent variables (age and gender of the trauma group, country where the study was performed, year of publication, type of event, time elapsed between event and measurement) and stress symptoms.

Data from 66 studies that used Horowitz's IES to examine the psychological impact of a major life event were subjected to meta-analysis.

Results from hierarchical regression analysis indicated that type of event (episodes of illness and injury, natural and technological disaster, bereavement and loss, violence, sexual abuse, and war exposure) is a strong predictor of levels of intrusive and avoidant symptoms after a traumatic event. Intrusive and avoidant reactions reported by trauma victims tended to decrease linearly over time after the trauma. This finding was supported by the results reported by 20 different studies of stress reactions at two different time points after various events. Gender and cultural difference were relatively insignificant, whereas type of event induced different levels of stress reactions as measured with the IES.

These data provide evidence for the value of the IES as a measure of stress reactions in a number of different populations. Data summarized here will be useful as a comparison resource in future studies of stress response syndromes.