Massed vs Intensive Outpatient Prolonged Exposure for Combat-Related Posttraumatic Stress Disorder: A Randomized Clinical Trial

Importance: Improved, efficient, and acceptable treatments are needed for combat-related posttraumatic stress disorder (PTSD). Objective: To determine the efficacy of 2 compressed prolonged exposure (PE) therapy outpatient treatments for combat-related PTSD. Design, Setting, and Participants: This randomized clinical trial was conducted among military personnel and veterans at 4 sites in Texas from 2017 to 2019. Assessors were blinded to conditions. Data were analyzed from November 2020 to October 2022. Interventions: The interventions were massed-PE, which included 15 therapy sessions of 90 minutes each over 3 weeks, vs intensive outpatient program PE (IOP-PE), which included 15 full-day therapy sessions over 3 weeks with 8 treatment augmentations. The IOP-PE intervention was hypothesized to be superior to massed-PE. Main Outcomes and Measures: Coprimary outcomes included the Clinician-Administered PTSD Scale for Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) (CAPS-5) and the PTSD Checklist for DSM-5 (PCL-5) administered at baseline and posttreatment follow-ups. Measures ranged from 0 to 80, with higher scores indicating greater severity. Diagnostic remission and reliable change were secondary outcomes. Results: Among 319 military personnel and veterans screened, 234 were randomized (mean [SD] age, 39.20 [7.72] years; 182 [78%] male participants), with 117 participants randomized to IOP-PE and 117 participants randomized to massed-PE. A total of 61 participants (26%) were African American, 58 participants (25%) were Hispanic, and 102 participants (44%) were White; 151 participants (65%) were married. Linear mixed-effects models found that CAPS-5 scores decreased in both treatment groups at the 1-month follow-up (IOP-PE: mean difference, -13.85 [95% CI, -16.47 to -11.23]; P <.001; massed-PE: mean difference, -14.13 [95% CI, -16.63 to -11.62]; P <.001). CAPS-5 change scores differed from 1- to 6-month follow-ups (mean difference, 4.44 [95% CI, 0.89 to 8.01]; P =.02). PTSD symptoms increased in massed-PE participants during follow-up (mean difference, 3.21 [95% CI, 0.65 to 5.77]; P =.01), whereas IOP-PE participants maintained treatment gains (mean difference, 1.23 [95% CI, -3.72 to 1.27]; P =.33). PCL-5 scores decreased in both groups from baseline to 1-month follow-up (IOP-PE: mean difference, -21.81 [95% CI, -25.57 to -18.04]; P <.001; massed-PE: mean difference, -19.96 [95% CI, -23.56 to -16.35]; P <.001) and were maintained at 6 months (IOP-PE: mean change, -0.21 [95% CI, -3.47 to 3.06]; P =.90; massed-PE: mean change, 3.02 [95% CI, -0.36 to 6.40]; P =.08). Both groups had notable PTSD diagnostic remission at posttreatment (IOP-PE: 48% [95% CI, 36% to 61%] of participants; massed-PE: 62% [95% CI, 51% to 73%] of participants), which was maintained at 6 months (IOP-PE: 53% [95% CI, 40% to 66%] of participants; massed-PE: 52% [95% CI, 38% to 66%] of participants). Most participants demonstrated reliable change on the CAPS-5 (61% [95% CI, 52% to 69%] of participants) and the PCL-5 (74% [95% CI, 66% to 81%] of participants) at the 1-month follow-up. Conclusions and Relevance: These findings suggest that PE can be adapted into compressed treatment formats that effectively reduce PTSD symptoms. Trial Registration: ClinicalTrials.gov Identifier: NCT03529435.