With an estimated 200,000 - 600,000 post-9/11 service members and veterans suffering from combat-related posttraumatic stress disorder (PTSD; 7-20% of the 3 million who have deployed), there is an urgent need for accessible therapies that are highly effective in quickly treating PTSD to remission, enabling service members to stay fit for active duty and veterans to integrate well into civilian life. While combat-related PTSD can be successfully treated in post-9/11 active duty service members and veterans, recent studies indicate that they do not derive the same degree of benefit from evidence-based behavioral treatments (e.g., Prolonged Exposure; Cognitive Processing Therapy) as their civilian counterparts. This suggests that combat-related PTSD is uniquely different from PTSD in civilians and that treatments are needed that expand and augment established evidence-based treatments in order to address the distinctive elements of combat-related traumas.

Prolonged Exposure (PE) is the PTSD treatment most extensively evaluated in clinical trials with civilians and veterans, and there is strong scientific evidence to support its efficacy. In standard outpatient PE, patients participate in weekly session over the course of two to three months. However, given military work requirements, participation in standard outpatient services is not always feasible. In the largest PE study with post-911 active duty service members to date conducted by Foa and colleagues in 2018 found PE delivered in a massed format (i.e., ten 90-minute PE sessions delivered on weekdays over 2 weeks) results in similar treatment outcomes to those of PE delivered in the standard spaced format (i.e., ten 90-minute PE sessions delivered over 8 weeks).

The current study expands and augments the previous treatment protocol. More specifically, this study examines whether intensive PE protocols can improve on treatment outcomes for post-9/11 service members and veterans with combat-related PTSD. The purpose of this randomized clinical trial is to compare the efficacy Massed-Prolonged Exposure (Massed-PE, 15 90-minute sessions delivered over three weeks) versus Intensive Outpatient Prolonged Exposure protocol (IOP-PE, 15 days of treatment delivered over three weeks). In comparison with the Massed PE examined by Foa, Massed-PE in this study has been modified to include 50% more sessions and release from duty. IOP-PE has been further augmented and includes the following modifications: (1) the use of a team-based treatment approach; (2) clinic-based completion of daily homework assignments; (3) brief therapist feedback sessions after daily homework assignments; (4) enhanced social support; (5) focusing on patients' three most distressing traumas during imaginal exposure; (6) graduated imaginal exposure starting with the least distressing trauma; (7) an optional telescopic, brief, timeline review of all traumatic events that occurred during previous deployments; and (8) the completion of three posttreatment booster sessions. Up to 400 post-9/11 active duty military and veterans will be consented to obtain data from 230 for analysis. The main outcomes of the study include PTSD diagnoses and symptom severity as measured by the Clinician Administered PTSD Scale for the (CAPS-5) and the PTSD Checklist-for the Diagnostic and Statistical Manual for Mental Disorders, 5th Edition(PCL-5). Participants will be assessed at baseline, while in-treatment and at one-, three-, and six-months after treatment completion. The researchers predict that IOP-PE will result in larger reductions than the Massed-PE in PTSD symptoms at the three follow-up assessments.