Objective: The first aim of this work was to conduct a rigorous longitudinal study to identify rates of delayed-onset posttraumatic stress disorder (PTSD) in a sample of patients with severe injury. The second aim was to determine what variables differentiated delayed-onset PTSD from chronic PTSD.
Methods: Randomly selected patients with injury who were admitted to four hospitals around Australia were recruited to the study (N = 834) and assessed in the acute care hospital, at 3 months, and at 12 months. A structured clinical interview was used to assess PTSD at each time point.
Results: Seventy-three patients (9%; n = 73) had PTSD at 12 months. Of these, 39 (53%) were classified as having delayed-onset PTSD. Furthermore, 22 (56%) patients with delayed-onset PTSD had minimal PTSD symptoms at 3 months (i.e., they did not have partial/subsyndromal PTSD at 3 months). The variables that differentiated delayed-onset PTSD from chronic PTSD were greater injury severity (odds ratio [OR] = 1.13; 95% confidence interval [CI] = 1.02-1.26), lower anxiety severity at 3 months (OR = 0.73; 95% CI = 0.61-0.87), and greater pain severity at 3 months (OR = 1.39; 95% CI = 1.06-1.84).
Conclusions: Delayed-onset PTSD occurred frequently in this sample. Approximately half of the patients with delayed-onset PTSD had minimal PTSD symptoms at 3 months; therefore, their delayed-onset PTSD could not be accounted for by a small number of fluctuating symptoms. As we move toward DSM-V, it is important that research continues to explore the factors that underpin the development of delayed-onset PTSD.