(PS13-97) Expectancy and Credibility in PTSD Treatment Response in Primary Care

Abstract Text: Expectancy is widely considered an influential common factor for therapeutic outcomes, regardless of theoretical orientation or approach. However, its correlation with Post Traumatic Stress Disorder (PTSD) treatment outcome, particularly in veteran populations, has not been adequately investigated. Assessment of expectancy and credibility is minimal for studies involving Prolonged-Exposure (PE) and nearly non-existent for Prolonged Exposure for Primary Care (PE-PC). In addition, studies examining expectancy during brief mental health treatment in primary care is also in need of empirical examination. We hypothesize that patients who have higher expectancies and assign the treatment higher credibility will have better self-reported outcomes. As part of a larger randomized clinical trial, Improving Function Through Primary Care Treatment of PTSD (IMPACT), 120 Veterans who presented in VA Primary Care Mental Health Integration were enrolled and randomized into one of two groups: Treatment as Usual (Primary Care Mental Health Integration) or PE-PC. Participants completed a variety of measures including the WHO Disability Assessment Schedule (WHODAS), Clinician Administered PTSD Scale for DSM-5 (CAPS-5), PTSD Checklist for DSM-5 (PCL-5), Patient Health Questionnaire (PHQ-9), Combat Experiences Scale (CES), and the Credibility Expectancy Questionnaire (CEQ). The CEQ was given at all self-report timepoints (baseline, 6 weeks, 12 weeks, and 24 weeks) and measured the participants’ expectations of and belief in the treatment (i.e., how much they feel the therapy will help reduce symptoms). Previously published outcomes demonstrated both PE-PC and TAU resulted in significant reductions in PTSD and improved function over 6, 12 and 24 weeks (Rauch, Kim, et al., 2023). A secondary analysis of the data was conducted to assess the relationship between expectancy and PTSD symptom and functional outcomes. Regression analysis showed a statistically significant positive relationship between changes in WHODAS scores and expectancy over 24 weeks (z=2.29; p=0.022), where expectancy was associated with greater functional improvement. Regression analysis showed a statistically significant positive relationship between changes in WHODAS scores and credibility over 24 weeks (z=2.38; p=0.017). Neither expectancy nor credibility showed any significant association with changes in PCL score after removal of a single outlier. Though often measured, patient expectancy and credibility is not fully understood in the context of PTSD treatment in primary care as well as PE-PC treatment. Examination of expectancy and credibility can inform treatment planning and potentially improve retention and outcomes.