Added value of Mindfulness-Based Cognitive Therapy for Depression: A Tree-based Qualitative Interaction Analysis

Aim: To identify moderators of treatment effect for Mindfulness-Based Cognitive Therapy (MBCT) versus Treatment As Usual (TAU) in depressed patients. Methods: An individual patient data-analysis was performed on three randomized-controlled trials, investigating the effect of MBCT + TAU versus TAU alone (N = 292). Patients were either in (partial) remission, currently depressed or had chronic, treatment-resistant depression. Outcomes were depressive symptoms and quality of life. The Qualitative INteraction Trees (QUINT) method was used to identify subgroups that benefited more from either condition. Results: MBCT + TAU outperformed TAU in reducing depressive symptoms. For both conditions, the effect of baseline depressive symptoms on post-treatment depressive symptoms was curvilinear. QUINT analyses revealed that MBCT + TAU was more beneficial than TAU for patients with an earlier onset and higher rumination levels in terms of depressive symptom reduction and for patients with a lower quality of life in terms of improving quality of life. Conclusions: The results suggest that MBCT might be more beneficial for those with earlier onset and higher levels of rumination and for patients with a lower quality of life. Sophisticated analytical techniques such as QUINT can be used in future research to improve personalized assignment of MBCT to patients. Long-term outcome could also be integrated in this.