Homework Completion, Patient Characteristics, and Symptom Change in Cognitive Processing Therapy for PTSD.

We evaluated the impact of homework completion on change in PTSD symptoms in the context of two randomized controlled trials of Cognitive Processing Therapy for PTSD (CPT). Female participants (n = 140) diagnosed with PTSD attended at least one CPT session and were assigned homework at each session. The frequency of homework completion was assessed at the beginning of each session and PTSD symptoms were assessed every other session. Piecewise growth models were used to examine the relationship between homework completion and symptom change. CPT version (with vs without the written trauma account) did not moderate associations between homework engagement and outcomes. Greater pretreatment PTSD symptoms predicted more Session 1 homework completion, but PTSD symptoms did not predict homework completion at other timepoints. More homework completion after Sessions 2 and 3 was associated with less change in PTSD from Session 2 to Session 4, but larger pre-to-post treatment changes in PTSD. Homework completion after Sessions 2 and 3 was associated with greater symptom change among patients who had fewer years of education. More homework completion after Sessions 8 and 9 was associated with larger subsequent decreases in PTSD. Average homework completion was not associated with client characteristics. In the second half of treatment, homework engagement was associated with less dropout. The results suggest that efforts to increase engagement in homework may facilitate symptom change.