Collaborative community mental health and aged care services with peer support to prevent late-life depression: study protocol for a non-randomised controlled trial

BACKGROUND: Late-life depression is common, modifiable, yet under-treated. Service silos and human resources shortage contribute to insufficient prevention and intervention. We describe an implementation research protocol of collaborative stepped care and peer support model that integrates community mental health and aged care services to address service fragmentation, using productive ageing and recovery principles to involve older people as peer supporters to address human resource issue. METHODS/DESIGN: This is a non-randomised controlled trial examining the effectiveness and cost-effectiveness of the “Jockey Club Holistic Support Project for Elderly Mental Wellness” (JC JoyAge) model versus care as usual (CAU) in community aged care and community mental health service units in 12 months. Older people aged 60 years and over with mild to moderate depressive symptoms or risk factors for developing depression will be included. JoyAge service users will receive group-based activities and psychoeducation, low-intensity psychotherapy, or high-intensity psychotherapy according to the stepped care protocol in addition to usual community mental health or aged care, with support from an older peer supporter. The primary clinical outcome, depressive symptoms, and secondary outcomes, self-harm risk, anxiety symptoms, and loneliness, will be measured with the Patient Health Questionnaire-9 (PHQ-9), Self-Harm Inventory, Generalized Anxiety Disorder 7-item scale (GAD-7), and UCLA Loneliness 3-item scale (UCLA-3) respectively. Cost-effectiveness analysis will assess health-related quality of life using the EQ-5D-5L and service utilisation using the Client Service Receipt Inventory (CSRI). We use multilevel linear mixed models to compare outcomes change between groups and calculate the incremental cost-effectiveness ratio in terms of quality-adjusted life years. DISCUSSION: This study will provide evidence about outcomes for older persons with mental health needs receiving collaborative stepped care service without silos and with trained young-old volunteers to support engagement, treatment, and transitions. Cost-effectiveness findings from this study will inform resource allocation in this under-treated population. TRIAL REGISTRATION: ClinicalTrials.gov NCT03593889. Registered on 20 July 2018. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06122-1.