Evaluating effectiveness and engagement strategies for asynchronous, messaging, trauma-focused therapy for posttraumatic stress disorder: Study design and methodology for a hybrid effectiveness-implementation randomized controlled trial.

Posttraumatic stress disorder (PTSD) can be a chronic and debilitating condition with significant individual and societal costs. Despite the availability of effective, trauma-focused treatments like Cognitive Processing Therapy (CPT), access and sustained engagement remain limited due to logistical, financial, and stigma-related barriers. The current study utilized a hybrid effectiveness-implementation randomized control trial (N = 300) to evaluate the clinical effectiveness and feasibility of CPT-Text, an asynchronous, therapist-delivered messaging version of CPT, compared to culturally informed treatment-as-usual (CI-TAU) delivered via secure text on the Talkspace platform. Participants were also randomized to receive either standard engagement reminders (RAU) or a novel engagement incentive (RAU + I), which encourages altruism by offering participants the opportunity to "pay forward" credits for free therapy to another PTSD-affected individual through their continued participation. Primary outcomes include PTSD symptom severity (PCL-5) and engagement (e.g., treatment completion and messaging frequency), with secondary outcomes assessing depression, functioning, satisfaction, substance use. We hypothesize that CPT-Text will outperform CI-TAU in symptom reduction, and that RAU + I will enhance engagement and outcomes. Exploratory analyses will examine individual-level moderators and motivation as a mechanism of change. A novel component of this trial includes development of a large language model-based fidelity assessment tool for CPT-Text, allowing scalable evaluation of treatment delivery. Findings will inform scalable, effective, and accessible PTSD interventions that meet the needs of individuals underserved by traditional mental health care, and provide insight into how human-delivered, technology-mediated therapy can be both clinically robust and broadly accessible. Evaluating Asynchronous Messaging Therapy for PTSD.