Validation of the Impact of Event Scale for Psychological Sequelae of Combat

The purpose of this study was to validate the Impact of Event Scale (IES) with a large sample of male subjects who had been exposed to the trauma of combat. Three groups of subjects were compared: (a) subjects who had participated in combat and had been identified as suffering from combat stress reaction; (b) control subjects who had participated in the same battles and were matched on relevant sociodemographic characteristics but had not shown symptoms of combat stress reaction; and (c) combat-ready subjects who were similar to the other groups but had not actively participated in battle. The basic scale structure was replicated. The IES was shown to be sensitive to differences between and within groups. Four basic patterns of intrusion and avoidance were identified. Discussion was focused on the theoretical issues associated with these patterns and on the effects of different types of trauma, and the need for clear criteria for diagnosis and treatment was indicated.