Background and Theoretical Framework This Type 2 Hybrid Implementation-Effectiveness Trial is designed to address the critical gap in posttraumatic stress disorder (PTSD) treatment for patients who have experienced co-occurring physical illness, namely cardiovascular (CV) events. Approximately one-third of CV event survivors develop PTSD, which serves as an independent risk factor for further CV morbidity and mortality. This study utilizes the Enduring Somatic Threat (EST) model, which posits that PTSD is driven by a persistent internal threat and can manifest as Fear-Related Behavioral Avoidance (FRBA). FRBA often leads to poor medication adherence and avoidance of necessary physical activities, creating a recursive cycle of poor health outcomes.
The NurseNET Intervention
The core of the experimental arm is Nurse-delivered Narrative Exposure Therapy (NurseNET), an evidence-based, four-session protocol integrated directly into the primary care (PC) setting. The treatment is delivered by specially trained nurses and follows a manualized structure:
Session 1: Includes psychoeducation regarding medical trauma and the co-reconstruction of a "Lifeline", a chronological, autobiographical narrative of the patient's life events.
Sessions 2-4: Focus on gradual imaginative exposure, where the nurse guides the patient to systematically process and extinguish trauma-related fear memories.
Safety Component: Every session concludes with structured somatic relaxation or "grounding" exercises to help participants regulate emotional arousal.
Study Design and Objectives Participants (N=100) are randomized 1:1 to either the NEST intervention or minimally-enhanced usual care (UC). The UC arm receives identical psychoeducation but is provided with external referrals for trauma treatment rather than co-located, nurse-led care.
The trial aims to evaluate three primary domains:
Effectiveness: Assessing changes in PTSD symptom severity (PCL-5) as the primary outcome, alongside secondary measures of depression (PHQ-9), anxiety (GAD-7), and CV-specific outcomes like blood pressure and medication adherence.
Implementation: Using the Consolidated Framework for Implementation Research (CFIR) to identify contextual drivers and implementation outcomes (acceptability, feasibility, and fidelity) to develop a replicable blueprint for future large-scale integration.
Cost-Effectiveness: Conducting a preliminary analysis of direct intervention costs and healthcare resource utilization (e.g., ED visits and hospitalizations) over 12 months.
Safety and Monitoring To ensure participant safety, a Data Safety Monitoring Committee (DSMC) will conduct interim reviews when 25% and 50% of the target sample is reached. The study excludes individuals with acute safety risks, such as active suicidal ideation, and provides clinical consultation with psychiatry and psychology for managing acute distress if it arises during exposure sessions.
