The authors of the report clearly explain:
"Effective disaster mental health planning and response depend on accurate information about the numbers of people who will need distinct types of services. In large-scale disasters such as the September 11, 2001 attacks affecting large populations, estimated proportions may translate into tens and hundreds of thousands of people needing services. Yet even though the 9/11 attacks constituted an undeniable trauma, the occurrence of a traumatic event is not sufficient for the diagnosis of PTSD; a qualifying exposure to the traumatic event is also necessary for consideration of this diagnosis. Exposure cannot be assumed; it must be determined on a case-by-case basis."
Here is how the research was conducted: Researchers examined disaster trauma exposure and its relationship to PTSD in a sample of 379 employees of eight New York City organizations (176 from WTC tower companies and 203 from organizations not in the towers) with a range of exposures, including some who were evacuated from the WTC towers and others who were nearby.
The study's participants were interviewed with the Diagnostic Interview Schedule/Disaster Supplement and symptoms assessed by the DSM-IV-TR qualifying 9/11 trauma exposures: physical endangerment (by planes striking the towers and collapse of the towers, fleeing the falling towers and debris, physical injury in the attacks); witnessing injury to others either during the attacks or during the aftermath at the Ground Zero site during the recovery operation (e.g., people falling from the towers, people with severe injuries, dead bodies and body parts); and through exposures of close associates (i.e., immediate family members/friends).
Study participants provided information approximately three years after the 9/11 attacks and a follow-up assessment was conducted at approximately six years post-disaster. In addition, factored in was the study participant's geographical proximity by a calculation of the nearest reported location to the towers during the attacks.
The authors continue:
"The post disaster prevalence rate of PTSD in the first three years was 35% of those in the towers or nearby who were directly exposed to physical danger in the attacks, a finding that is remarkably consistent with the 34% PTSD incidence identified among directly exposed survivors of the Oklahoma City bomb blast in the first six months using the same assessment tool. These findings collectively suggest that among highly exposed survivors of severe terrorist incidents, one-third may be expected to develop PTSD."
Furthermore, the authors conclude:
"Reflecting on a decade of mental health research on the 9/11 attacks, it is clear that the complexities of exposure in estimation of PTSD present a substantial challenge to researchers to provide accurate information to guide disaster mental health planning. A substantial proportion of people in the current study who were directly exposed to physical danger or exposed through close associates developed PTSD. This PTSD was relatively persistent. Among those outside of a small geographic distance from the towers without known qualifying exposures, who cannot by definition be diagnosed with PTSD, a small proportion, representing potentially large numbers of people in extended populations, may develop similar symptoms."
Written by Sy Kraft