PTSD combined with risky substance use (RSU) poses significant treatment challenges, particularly in resource-limited community healthcare settings. Approximately 50% of individuals with PTSD experience comorbid RSU, contributing to high dropout rates and limited treatment effectiveness. To address these barriers, this project employs a hybrid experimental design (HED), combining Sequential Multiple Assignment Randomized Trial (SMART) and micro-randomized controlled trial (MRT) methodologies.

The research aims to develop and refine a stepped care intervention sequence integrating both therapist-delivered and digital (text-based) strategies for PTSD and RSU in FQHC settings. The project includes two primary aims:

Aim 1: Assess feasibility and acceptability of three therapist-delivered PTSD+RSU interventions. Patients at a partner FQHC will initially receive either Written Exposure Therapy or Clinician-Supported PTSD Coach. Based on their responses, they may continue with the initial approach or step up to a more intensive treatment integrating motivation and exposure therapy. Daily monitoring of PTSD symptoms and substance use will inform ongoing treatment and assess intervention acceptability.

Aim 2: Refine intervention components through semi-structured qualitative interviews with patients and therapists, identifying effective elements, problematic areas, and opportunities for improvement. Feedback will guide enhancements, such as adjusting therapy focus and session structures to minimize dropout and improve patient engagement.

This foundational work will prepare for a larger-scale HED aimed at reducing PTSD symptoms and risky substance use, ultimately improving treatment access and outcomes for underserved community health populations.