OBJECTIVE:

Previous studies investigating the relationship between acute stress disorder (ASD) and posttraumatic stress disorder (PTSD) have reported mixed findings and have been flawed by small sample sizes and single sites. This study addresses these limitations by conducting a large-scale and multisite study to evaluate the extent to which ASD predicts subsequent PTSD.

METHOD:

Between April 2004 and April 2005, patients admitted consecutively to 4 major trauma hospitals across Australia (N = 597) were randomly selected and assessed for ASD (DSM-IV criteria) during hospital admission (within 1 month of trauma exposure) and were subsequently reassessed for PTSD 3 months after the initial assessment (N = 507).

RESULTS:

Thirty-three patients (6%) met criteria for ASD, and 49 patients (10%) met criteria for PTSD at the 3-month follow-up assessment. Fifteen patients (45%) diagnosed with ASD and 34 patients (7%) not diagnosed with ASD subsequently met criteria for PTSD. The positive predictive power of PTSD criteria in the acute phase (0.60) was a better predictor of chronic PTSD than the positive predictive power of ASD (0.46).

CONCLUSIONS:

The majority of people who develop PTSD do not initially meet criteria for ASD. These data challenge the proposition that the ASD diagnosis is an adequate tool to predict chronic PTSD.