Valid cases of PTSD are not common. A study [Schnyder, U. et al. (2001) Incidence of prediction of prevalence of posttraumatic stress disorder in severely injured accident victims. Amer. J. Psych. 158, 4, 594-599.] remind us that symptoms of PTSD cannot be diagnosed until symptoms have lasted for at least one month.
Thus, when there is a claim of PTSD immediately following an accident, it is not clinically valid, and it may be a transient adjustment response.
In the aforementioned study, 4.7% met the criteria for PTSD after one month, and one year later 1.9% met the criteria for PTSD.
Of the few that developed PTSD, it was found more common in those who had few friends or relatives, and it was more common in women.
Higher reported PTSD may be from misdiagnosis in which the label is attached to those who have several symptoms but did not, in fact, meet criteria for actual diagnosis as define in the DSM-IV-TR.
This, once again, points to the importance of obtaining valid diagnostic examination when PTSD is suspected.