Association between index trauma timing and treatment retention and symptom severity in women receiving prolonged exposure therapy for PTSD and substance use disorder

Purpose Women with co-occurring post-traumatic stress disorder (PTSD) and substance use disorder (SUD) demonstrate high attrition during integrated prolonged exposure (PE) psychotherapy. Existing exposure therapies identify an index trauma, which serves as the primary focus of exposure during treatment. The timing of trauma exposure (childhood vs adulthood) is known to influence symptom severity and treatment outcomes. Yet, whether the same is true for the timing of index trauma (childhood vs adulthood) is not well understood. The purpose of this study was to examine the impact of timing of index trauma on treatment retention, SUD severity, and mental health symptoms. Design/methodology/approach This retrospective cross-sectional observational study examined whether the timing of index trauma (childhood vs adulthood) was associated with treatment retention, SUD severity and baseline mental health among 55 women participating in integrated PE treatment for PTSD–SUD. Treatment retention was defined as completion of four or more sessions. SUD severity was measured using the Severity of Dependence Scale. Mental health was assessed based on symptoms of stress, anxiety and depression and borderline symptomatology at baseline. Findings There were no statistically significant associations between timing of index trauma and treatment retention, SUD severity or severity of mental health symptoms at baseline. Research limitations/implications The lack of a significant relationship in this study warrants further exploration of factors influencing treatment attrition and highlights a need for further research into the mechanisms of identification and operationalisation of index trauma in exposure therapy. Originality/value To the best of the authors’ knowledge, this is the first study to explore the relationship of the timing of index trauma (childhood vs adulthood) with treatment retention, SUD severity and baseline mental health symptoms. In addition, this study offers a unique perspective from its setting in a routine treatment clinic.