Els van Meijel

11 General introduction | Chapter 1 the traffic accident, for instance by falling. Another 30% were involved in interaction with others, for instance in collisions with cars, other bikes, or pedestrians. In sports- related accidents, the major causes of injuries are falls (58%) and being struck by a ball (15%). In this age group, the industrial category of accidents is the smallest. The most frequent causes are being hit by a moving object, getting trapped or being cut by an object. In private accidents the major causes of injuries are falls (57%) and bumping into an object (9%). After the accident, a relatively small proportion of the children are hospitalized (11% in traffic-related accidents, 4% in sports-related accidents, 5% in industrial accidents and 8% in private accidents). Accidents entail medical expenses and other costs such as delays in school progress and absence fromwork. Additionally, results of an explorative study suggest that the financial burden of injuries increases with one third if psychological consequences such as PTSD are included (VeiligheidNL, 2014). Ignoring PTSD leads to a considerable underestimation of the financial burden of injuries, whichmay negatively influence the identification of prevention priorities and resource allocations (Haagsma et al., 2011). Psychological impact of accidents and injury on children and their parents Posttraumatic Stress Disorder (PTSD) 3 A traumatic event may induce various psychological reactions, such as posttraumatic stress, anxiety or depression. In this thesis, the focus is on posttraumatic stress reactions and posttraumatic stress disorder (PTSD). According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the first criterion for PTSD is that the person was exposed to death, threatened death, actual or threatened serious injury, or actual or threatened sexual violence in one or more of the following ways: direct exposure, witnessing the trauma, learning that a relative or close friend was exposed to a trauma, 3 DSM-5 criteria were launched in 2013. The studies in this thesis were performed before, therefore, DSM-IV-TR criteria (APA, 2000) were applied. Compared to DSM-IV, the most important changes in DSM-5 are the following: a new qualification of traumatic events (A1); removal of the A2 criterion (a response of intense fear, hopelessness or horror), criterion C (avoidance and numbing) was split into criterion C (avoidance) and criterion D (negative alterations in cognitions and mood). Symptoms were also added in DSM-5: overly negative thoughts and assumptions about oneself or the world, negative affect and risky or destructive behavior. Finally, DSM-5 no longer differentiatiates between acute and chronic PTSD (PTSD can be assessed if symptoms last for more than one month).