Testing the Effectiveness of Process Based Therapy in Routine Patient Care and Assessing Its Influence on Therapist Decision Making

Process Based Therapy Applicability, Effectiveness and Compatibility (PBACE). A Within Therapist Randomized Controlled Trial Testing the Effectiveness of Process Based Therapy in Routine Patient Care and Assessing Its Influence on Therapist Decision Making

Background: Process Based Therapy (PBT) is a novel approach for a more personalized psychotherapy by integrating patient's ecological momentary assessment (EMA) data into treatment planning and focusing on empirically measured maladaptive processes. Previous pilot studies have examined the efficacy and feasibility of PBT in different settings. However, the effectiveness of this approach as well as the influence of providing EMA data on therapist's decision-making as well as treatment planning is yet unexplored.

Objective: This study aims to evaluate the effectiveness of PBT in a naturalistic setting as well examine the influence of the provision of EMA data on therapists' decision-making.

Methods: Thiry therapists as well as 60 patients will be recruited. Therapists will each treat two patients which are randomly allocated to either an intervention group receiving PBT or an active control group receiving routine psychotherapy. Treatment outcomes will be measured pre and post treatment as well as a 6-month follow-up. Therapists' decision making will be measured before training in PBT as well as during the treatment process using think aloud protocols (TAP) as well as quantitative measurements for decision making styles and self efficacy in decision making.

Discussion: This study could add insights into the ongoing research about the efficacy and effectiveness of PBT as well as provide insights into therapists' treatment decisions. While PBT holds theoretical promise for a more personalized and effective treatment, empirical data is still needed to assess its theoretical merit, which this study could provide. Expanding on the thus far scarce literature on decision-making in the therapeutic process, valuable information about processes guiding therapists' treatment decisions could be gained.

Inclusion Criteria:

• A primary ICD-11 diagnosis of a depressive or anxiety disorder
• Age 18-65 years
• Sufficient knowledge of the German language
• Participating patients are not required to discontinue medication, but to keep medication constant over the treatment period

Exclusion Criteria:

• Increased suicidality
• Substance abuse or dependency
• diagnosis of a cluster A or B (DSM-5) personality disorder
• pervasive developmental disorder, psychotic disorder, eating disorder, bipolar disorder, or severe physical illness.