The relationship between acute stress disorder and posttraumatic stress disorder: a 2-year prospective evaluation.

Previous research established that 78% of a sample of motor vehicle accident survivors initially diagnosed with acute stress disorder (ASD) were subsequently diagnosed with posttraumatic stress disorder (PTSD) at 6 months posttrauma. Although the previous study provided initial evidence for the utility of the ASD diagnosis, the relationship between ASD and PTSD was assessed over a relatively short period. The present study reassessed that original sample 2 years following the trauma to establish the longer term relationship between ASD and PTSD. ASD was diagnosed in 13% of participants, and 21% were diagnosed with subsyndromal ASD. In terms of participants who participated in all 3 assessments, 63% who met the criteria for ASD, 70% who met the criteria for subsyndromal ASD, and 13% who did not meet the criteria for ASD were diagnosed with PTSD at 2 years posttrauma. These findings indicate the importance of considering multiple pathways to the development of PTSD.