assessment. Similarly, the event-specific PTSD prevalence of symptoms to a given event type is narrower than the conditional risk of Same Event PTSD (to any specific event) among those with a given history of the event type (e.g., sexual or physical assault). Conditional probabilities of PTSD using Composite Event and event-specific PTSD to an individual event type (depicted in Table 5) differed substantially for some stressor events. For example, the conditional probability of PTSD given disaster exposure was 10.1% using the Composite Event definition, but only 0.4% using the more rigorous event-specific definition. Thus, a hurricane survivor may have re-experiencing symptoms related to natural disaster, but may experience other PTSD symptoms to another experienced traumatic event such as a physical or sexual assault. Similar patterns occurred for other stressor-event types. This indicates that some events may appear to have higher conditional probability of producing PTSD than is actually the case unless the assessment strategy determines whether PTSD symptomatology is attributable to the index event versus the combination of several traumatic events.
