Examining prolonged exposure outcomes when session frequency is limited: Preliminary findings from a Veteran sample

Unlike in efficacy trials, there can be notable variability in session frequency when PTSD treatment protocols, such a Prolonged Exposure (PE), are disseminated in clinical practice. The current study aimed to examine the impact of PE session frequency on treatment outcomes in a clinical Veteran sample. This study utilized retrospective data drawn from the Veterans Health Administration's Corporate Data Warehouse, a national data repository which includes Electronic Health Records. The extracted cohort of 648 Veterans was majority White-non-Hispanic and male [(M_age = 55.66 (14.08)]. All Veterans had a diagnosis of PTSD and completed in-person PE in outpatient Veterans Affairs behavioral health clinics between 2017 and 2018. The treatment outcome measure was the PTSD Checklist for DSM-5 (PCL-5). Linear multiple regression analyses did not find that session frequency predicted treatment outcome. Likewise, t-test results did not find differences in PCL-5 change scores based on session frequency. Effect sizes for pre- to post-treatment PCL-5 change scores ranged from d = 1.25 to 1.40. Overall, the current study suggests that PE may still be a useful intervention even when the treatment manual recommendation of weekly or twice weekly sessions cannot feasibly be conducted in clinical practice. Cross-validation is needed.