The D*Phase-study: study protocol for a pragmatic two-phased, randomised controlled (non-inferiority) trial that addresses treatment non-response and compares cognitive behavioural therapy and short-term psychodynamic supportive psychotherapy for major depression

Background: Several evidence-based psychotherapeutic treatment options are available for depression, but the treatment results could be improved. The D*Phase study directly compares short-term psychodynamic supportive psychotherapy (SPSP) and cognitive behavioural therapy (CBT) for Major Depressive Disorder (MDD). The objectives are 1. to investigate if, from a group level perspective, SPSP is not inferior to CBT in the treatment of major depressive disorder, 2. to build a model that may help predict the optimal type of treatment for a specific individual; and 3. to determine whether a change of therapist or a change of therapist and treatment method are effective strategies to deal with non-response. Furthermore (4.), the effect of the therapeutic alliance, treatment integrity and therapist allegiance on treatment outcome will be investigated. Method: In this pragmatic randomised controlled trial, 308 patients with a primary diagnosis of MDD are being recruited from a specialised mental health care institution in the Netherlands. In the first phase, patients are randomised 1:1 to either SPSP or CBT. In case of treatment non-response, a second phase follows in which non-responders from treatment phase one are randomised 1:1:1 to one of three groups: continuing the initial treatment with the same therapist, continuing the initial treatment with another therapist or continuing the other type of treatment with another therapist. In both treatment phases, patients are offered sixteen twice-weekly psychotherapy sessions. The primary outcome is an improvement in depressive symptoms. Process variables, working alliance and depressive symptoms, are frequently measured. Comprehensive assessments take place before the start of the first phase (at baseline), in week one, two and four during the treatment, and directly after the treatment (week eight). Discussion: While the naturalistic setting of the study involves several challenges, we expect, by focusing on a large and diverse number of research variables, to generate important knowledge that may help enhance the effect of psychotherapeutic treatment for MDD. Trial registration: The study was registered on 26 August 2016 with the Netherlands Trial Register, part of the Dutch Cochrane Centre (NL5753), https://www.trialregister.nl/trial/575