Abstract
BACKGROUND: Adolescent major depressive disorder (MDD) is a prevalent mental health problem with low treatment success rates. Whether fluoxetine or fluoxetine combined with cognitive-behavioural therapy (CBT) is the more effective initial treatment for adolescent MDD remains controversial, and few studies have investigated whether treatment switching or augmentation is preferred when the initial treatment is not working well. METHODS: We developed a multicentre open-label Sequential Multiple Assignment Randomized Trial (SMART) design, consisting of two phases lasting 8 weeks each. In phase 1 (at baseline), patients will be recruited and grouped in fluoxetine group or fluoxetine combined with CBT group by patient self-selection. In phase 2 (after 8 weeks of treatment), the nonresponders will be randomly assigned to six groups, in which participants will switch to sertraline, vortioxetine, or duloxetine or added aripiprazole, olanzapine, or lithium carbonate to fluoxetine. After the full 16 weeks of treatment, we will assess the long-term sustainability of the treatment effects by evaluating participants during their subsequent naturalistic treatment. The primary outcome will be the response rate, determined by the Children's Depression Rating Scale-Revised (CDRS-R). Secondary outcomes include the change in scores on the Beck Depression Inventory (BDI), the Screen for Child Anxiety-Related Emotional Disorders (SCARED) and the Safe Assessment. DISCUSSION: The results from this study will aid clinicians in making informed treatment selection decisions for adolescents with MDD. TRIAL REGISTRATION: This protocol was registered at ClinicalTrials.gov with Identifier: NCT05814640.