Assessing the impact of stressful incidents in organizations: The development of an extended impact of events scale

Employers are becoming increasingly aware of the risks to employee wellbeing associated with the traumatic incidents that occur in the workplace. Despite this increased organizational awareness of the need to protect employees from the damaging effects of traumatic events, there has been little provision to help organizations to evaluate their management systems and post trauma interventions. This problem of a lack of evaluation has become more important as a growing body of evidence has provided evidence that suggests that trauma debriefing, the widely used approach to traumatic stress may be ineffective or damaging. The problem for an organization is to have a means of assessing the impact of a traumatic incident on exposed employees soon after the event and at regular intervals as a way of tracking the effectiveness of the treatment and rehabilitation programme. This paper examines the development and validation of a traumatic stress questionnaire designed to be used by trained practitioners working with traumatized employees. The extended impact of events scale (IES-E), took the 15 items from the impact of events scale (IES) and added eight new items which had been chosen on the basis of existing theory and clinical experience to represent the traumatic stress symptom of hyperarousal. Two studies are reported which examine the structure and reliability, and then the discriminant validity of the extended scale when used with a working population. The first study involved a factor analysis of the IES-E items using data collected from 105 subjects who had formally reported exposure to stressful work events to their employing organization. The second study then used the IES-E to compare employees self-reporting of the impact of either a major positive or a major negative life event. The results of the first study confirmed the presence of the re-experience and avoidance symptoms as a response to a traumatic event (as in the IES) but, in addition, identified a new factor, arousal and a new measurement model based on a single general factor. The reliability coefficients for all three scales and the general factor were found to be good. The second study showed that IES-E scores on re-experience, avoidance, arousal and the general factor could be used to discriminate between the subjects reporting major positive and negative life events. Two measurement models can therefore describe the impact of stressful events, the first based on three orthogonal factors, and the second based on a single general factor. The theoretical implications of these findings are explored.