Furukawa TA Karyotaki E Suganuma A Pompoli A Ostinelli EG Cipriani A Cuijpers P Efthimiou O 2019 INTRODUCTION Psychotherapy is a complex intervention, consisting of various components and being implemented flexibly in consideration of individual patient's characteristics. It is then of utmost importance to know which of the various components or combinations thereof are more efficacious, what their specific effect sizes are and which types of patients may benefit more from different components or their combinations. METHODS AND ANALYSIS Internet-delivered cognitive-behavioural therapy (iCBT) offers a unique opportunity to systematically review and quantitatively disentangle the efficacy of various components because, unlike face-to-face cognitive-behavioural therapy, it allows identification of constituent components that are actually delivered to patients. We will systematically identify all randomised controlled trials that compared any form of iCBT against another form or a control intervention in the acute phase treatment of adult depression. We will apply component network meta-analysis (cNMA) to dismantle efficacy of individual components. We will use individual participant data in the cNMA to identify participant-level prognostic factors and effect modifiers for different components. ETHICS AND DISSEMINATION The investigators of the primary trials will have obtained ethical approval for the data used in the present study and for sharing the data, if this was necessary, according to local requirements and was not covered from the initial ethic assessment. Results from this study will be published in peer-reviewed journals and presented at relevant conferences. PROSPERO REGISTRATION NUMBER CRD42018104683. application/pdf https://sonar.ch/global/documents/278970 eng info:eu-repo/semantics/altIdentifier/doi/10.1136/bmjopen-2018-026137 info:eu-repo/semantics/altIdentifier/pmid/30798295 info:eu-repo/semantics/openAccess BMJ open. - 2019 depressive disorder individual participant data meta-analysis internet-delivered cognitive-behavioral therapy network meta-analysis Cognitive Behavioral Therapy Depressive Disorder Humans Internet Network Meta-Analysis Outcome Assessment, Health Care Randomized Controlled Trials as Topic Research Design Systematic Reviews as Topic Systems Analysis Dismantling, personalising and optimising internet cognitive-behavioural therapy for depression: a study protocol for individual participant data component network meta-analysis. http://purl.org/coar/resource_type/c_6501