Abstract
Response to weekly evidence-based PTSD treatments varies. Little is known about response trajectories and predictors in intensive PTSD treatments. This study sought to identify different trajectories of symptom change among veterans who completed a 3-week CPT-based intensive PTSD treatment program and examined potential predictors of trajectory group membership. Four hundred fifty-two veterans completed the program. Demographics, PTSD and depression severity, negative posttrauma cognitions, and alcohol use were assessed at intake and evaluated as possible predictors of group membership. Group based trajectory modeling was used to determine distinct groups based on PTSD symptom trajectory over the course of treatment, as well as predictors of group membership. Four distinct treatment trajectories were identified: Fast responders (15.3%), steady responders (32.0%), partial responders (38.4%), and minimal responders (14.4%). Fast and steady responders reported substantial symptom reductions and dropped below the "probable PTSD" threshold, with fast responders achieving improvements after just one week of treatment. Partial responders experienced clinically significant reductions but remained above the "probable PTSD" threshold. Minimal responders reported the highest baseline PTSD symptoms and changed the least throughout treatment. Negative posttrauma cognitions as well as self-reported and clinician-rated PTSD symptom severity assessed at intake successfully predicted trajectory membership. The identified trajectories closely resemble findings in the limited existing literature on intensive PTSD treatment trajectories. Results suggest that some individuals may improve with even shorter interventions and others might benefit from additional treatment sessions. Overall, findings support the importance of evaluating individual- and group-level treatment responses.