Document Type



Doctor of Philosophy


Psychology, Clinical-Community

Date of Defense


Graduate Advisor

Steven Bruce, Ph.D.


Ann Steffen, Ph.D.

Michael Griffin, Ph.D.

Susan Kashubeck-West, Ph.D.


Cognitive Processing Therapy (CPT), a Cognitive Behavioral Therapy for treating Post Traumatic Stress Disorder (PTSD), is an evidence-based treatment that has been demonstrated to be effective in treating PTSD. Nonetheless, CPT can have a high rate of treatment non-completion. Attrition from therapy has been operationally defined using multiple contrasting methods. Understanding attrition using a definition with the most clinical utility is essential to improving outcomes from efficacious treatments. Two clinically relevant definitions for attrition, session attendance and symptom improvement, are critical to understanding attrition. Combining information from both definitions, to create four separate groups, will provide more accurate information about treatment outcomes, referred to as the Two-Part Definition of Attrition (TPDA). The present study examined factors related to treatment attendance, treatment response, and the TPDA. Examined in isolation, only initial depressive symptoms were related to treatment completion whereas both gender and initial depressive symptoms were related to treatment response. Using the TPDA, only two groups differed by initial depressive symptoms, early terminators and those who completed and responded to treatment as anticipated. This study demonstrates that the definition used for attrition will impact the results and in turn inform the application of the results. Specifically, these results can inform clinicians’ decisions to use strategies to reduce attrition with clients who are most at risk of unilaterally terminating treatment. Additionally, researchers may utilize these results to select the most relevant definition for their study.