Findings regarding the extent of exposure to multiple-event types and the extent to which multiple exposure resulted in higher risk of lifetime PTSD have implications for both how PTSD is conceptualized and for how it should be assessed. With respect to PTSD conceptualization, the field must move beyond a narrow focus on PTSD responses to a single event because it is clear from this and previous studies that exposure to multiple events is the norm and that the probability of PTSD increases with greater event exposure. These findings are consistent with previous reports indicating that prior- and/or multiple-traumatic-event exposure increases risk of PTSD (e.g., Ozer et al., 2003; Walsh et al., 2012). This pattern was also seen with the Same Event definition, suggesting a cumulative effect of exposure to prior-/multiple-event type(s) even when assessing PTSD in reference to a single-event type. Potential bidirectional associations between PTSD and traumatic-event exposure are also important to study and understand (e.g., Cougle, Resnick, & Kilpatrick, 2009).
