Dropout from prolonged exposure among individuals with posttraumatic stress disorder and comorbid severe mental illness

Background: Predictors of dropout in individuals with PTSD and a comorbid severe mental illness (SMI; i.e., schizophrenia, bipolar disorder) have yet to be investigated. As part of a larger randomized controlled trial evaluation of Prolonged Exposure for PTSD plus treatment as usual (PE+TAU) relative to treatment as usual (TAU) alone, the current study examined the following pretreatment predictors of PE dropout in 63 Veterans with PTSD and SMI: (1) PTSD symptom severity; (2) SMI symptom severity; (3) emotion regulation; and (4) patient demographic variables. Methods: A one-way ANOVA examined potential differences at pretreatment across predictor variables of interest between treatment completers (n = 29), participants who never initiated treatment (n = 9), and participants who initiated treatment but later discontinued (n = 25). Discrete time survival analysis using a proportional odds Cox ratio was fit to the data to examine treatment dropout. Results: Of the 63 Veterans enrolled in PE+TAU, 50 initiated treatment, and 29 completed PE. Hazard probabilities for dropout were greatest following sessions 1, 3, and 5. There were no significant predictors of dropout. Limitations: The obtained results are sample-specific and may not generalize to Veteran samples from other regions or community samples of individuals with SMI. Additionally, survival analysis cannot account for participants who never initiated treatment (n = 9). Conclusions: Most individuals with SMI who begin PE successfully complete the full course of treatment, but further investigation of variations in baseline characteristics among non-completer subgroups that may moderate PE outcomes is warranted.