Unveiling the neglected role of the intensity of acute stress disorder in the prediction of full- and sub-threshold posttraumatic stress disorder: looking beyond the diagnosis.

Purpose: Exposure to traumatic events may lead to the development of Acute Stress Disorder (ASD) within the first month post-trauma in some individuals, while others may not exhibit ASD symptoms. ASD was introduced as a potential early indicator to identify those at higher risk of developing Posttraumatic Stress Disorder (PTSD), however, PTSD can occur in some individuals even without prior ASD. Assessing ASD post-trauma can assist in identifying those who would most benefit from intervention to prevent later PTSD, yet the predictive power of ASD varies across studies, with intensity of ASD symptoms and subthreshold PTSD often less considered.

Methods: A prospective cohort study on 426 health workers exposed to the Beirut Port Blast assessed DSM-5 ASD and symptom intensity using self-report questionnaire at two distinct time points: 9-15 and 21-27 days post blast. DSM-5 PTSD was assessed afterwards at 6-7 months via self-report questionnaire post-exposure. Probit models predicted full and subthreshold PTSD.

Results: Using ASD diagnosis alone, the sensitivity 9-15 days after trauma was better than 21-27 days after trauma (75.68% vs. 58.06%); when stratified by intensity, however, sensitivity increased from 41.66% among those with low intensity to 92% among those with high intensity. Specificity, however, was better 21-27 days after trauma (77.82%) compared with 9-15 days (60.98%). Positive Predictive Value of ASD increased, and Negative Predictive Value decreased, with time since exposure and when adding intensity with diagnosis. ASD diagnosis plus intensity achieved better prediction of PTSD and subthreshold PTSD.

Conclusion: Screening for PTSD should include ASD and its intensity, improving predictive ability for later PTSD, incorporatingfull threshold and subthreshold PTSD. Specificity increases with time since exposure, suggesting a high rate of false positives when assessing ASD soon after trauma. This highlights the need to prioritize individuals for early preventive measures after trauma.