Outcomes reported in randomised controlled trials of major depressive disorder in older adults: protocol for a methodological review

Introduction Major depressive disorder (MDD or depression) is prevalent among adults aged 65 years and older. The effectiveness and safety of interventions used to treat depression is often assessed through randomised controlled trials (RCTs). However, heterogeneity in the selection, measurement and reporting of outcomes in RCTs renders comparisons between trial results, interpretability and generalisability of findings challenging. There is presently no core outcome set (COS) for use in RCTs that assess interventions for older adults with MDD. We will conduct a methodological review of the literature for outcomes reported in trials for adults 65 years and older with depression to assess the heterogeneity of outcome measures. Methods and analysis RCTs evaluating pharmacotherapy, psychotherapy, or any other treatment intervention for older adults with MDD published in the last 10 years will be located using electronic database searches (MEDLINE, Embase, PsycINFO and the Cochrane Central Register of Controlled Trials). Reviewers will conduct title and abstract screening, full-text screening and data extraction of trials eligible for inclusion independently and in duplicate. Outcomes will be synthesised and mapped to core outcome-domain frameworks. We will summarise characteristics associated with trials and outcomes. Ethics and dissemination We hope that findings from our methodological review will reduce variability in outcome selection, measurement and reporting and facilitate the development of a COS for older adults with MDD. Our review will also inform evidence synthesis efforts in identifying the best treatment practices for this clinical population. Ethics approval is not required, as this study is a literature review. PROSPERO registration number CRD42021244753.