BRIDGE – Behavioral and physical activation for multimorbid older adults with depressive symptoms during the inpatient to outpatient transition: study protocol for a multicenter two-arm randomized controlled trial

Background:Older adults with multimorbidity and depressive symptoms are particularly vulnerable during the transition from (partial) inpatient to outpatient care, with a high risk of readmission and rehospitalization due to substantial barriers in accessing appropriate mental healthcare. The BRIDGE intervention addresses this critical transition through a structured, manualized, interdisciplinary treatment program aimed primarily at improving depressive symptoms.Methods:BRIDGE is a 12-week blended care intervention that combines two evidence-based therapeutic strategies—behavioral activation (BA) and physical exercise (PE)—to promote structured daily activity and improve mood and physical health. The program is delivered by an interprofessional team consisting of a nurse, psychologist, and exercise scientist at each study center, and includes both home visits and digital components via a tablet-based e-health platform. Core elements comprise BA exercises in line with behavioral change techniques, and a video-guided home-based PE program. The multicenter two-arm randomized controlled trial evaluates the efficacy, feasibility, and cost-effectiveness of the BRIDGE intervention compared to treatment as usual. The post-discharge maintenance or improvement of the outcome of inpatient treatment for depressive symptoms is considered as the primary outcome. Secondary outcomes include reductions in recurrent hospital admissions, improvements in physical, emotional, and cognitive functioning as well as quality of life, and evidence of a favorable cost-effectiveness ratio.Discussion:BRIDGE offers a comprehensive, scalable intervention model that integrates behavioral and physical activation into the daily life of older patients with multimorbidity and depressive symptoms. By embedding hybrid delivery formats, structured interprofessional collaboration, and a focus on sustainable home-based routines, the intervention addresses the complex needs of older multimorbid adults during a critical care transition. Findings from this trial will inform future implementation in diverse healthcare settings and contribute to evidence-based service development in geriatric mental health.