Factors that are related to the traumatic event are important in the development of posttraumatic stress. Perceived severity and the timing of the traumatic experience are among the factors related to the event.

In the literature, the perceived severity of the traumatic experience was found to be related to the development of PTSD in trauma survivors (Malt, Hoivik,& Blikra, 1993; Ehlers, et. al, 1998; Dörfel et al., 2008). In terms of investigating the impact of the motor vehicle accident severity on the occurrence of PTSD, Blanchard, Hickling, Mitnick, Taylor, Loos, and Buckley (1995) indicated that PTSD symptoms of motor vehicle accident survivors were predicted by the severity of the injury. Furthermore, the results of the 3-year follow up study conducted with traffic accident survivors revealed that the injury severity that was evaluated by the nurse of the orthopedics department, significantly predicted both the occurrence and severity of PTSD (Mayou, Ehlers, & Bryant, 2002).

Additionally, the findings of the study conducted with 44 severe traffic accidents survivors, indicated that the self-reported severity of the accident predicted PTSD severity (Dörfel, Rabe, & Karl, 2008). Similarly, the results of the study conducted with traffic accident survivors from Turkey were in consistency with these findings (Turan, Eşel, & Keleş, 2002). They found out that people who rated the accident as very severe showed significantly more PTSD symptoms than those who reported the accident as mildly severe.

However, there was no correlation between injury severity and PTSD symptoms in other research findings (Mayou, Bryant, & Duthie, 1993; Schnyder, Moergeli, Klaghofer, Buddeberg, 2001).

In the literature, timing of the traumatic event was found to be related to the development of PTSD following traumatic experiences (Southwick, Morgan, & Darnell, 1995; McFarlane, Atchison, & Yehuda, 1997; Grieger, Cozza, Ursano, Hoge, Martinez, Engel, & Wain, 2006). The results of the longitudinal study conducted with accident survivors showed that the passage of time was positively related with the development of PTSD symptoms (McFarlane et al., 1997). Furthermore, Grieger et al. (2006), in their study conducted with soldiers injured in a battle, demonstrated that the more the passage of time, the more is the risk of developing PTSD.