Study Protocol: Connecting older adults through multi-level programmes for alleviating loneliness in Hong Kong older adults (COMPASS-HOA).

Background: Loneliness is a widespread global issue among older adults that negatively impacts physical and mental health, cognitive functioning, quality of life, and longevity, while also burdening society with healthcare costs. Resulting from factors at individual, interpersonal, and community levels. Multi-level interventions targeting these levels show promise in addressing this complex issue. Objective: This trial aims to develop, implement, and evaluate a multi-level intervention comprising individual-, interpersonal-, and community-level components to reduce loneliness and enhance well-being among older adults in Hong Kong. Methods: This pragmatic, assessor-blinded, 4-arm cluster randomized controlled trial will evaluate a multi-level intervention among 1,344 community-dwelling lonely older adults living in poverty. Participants will be randomized equally to one of the four 6-month intervention groups delivered by trained volunteers: individual-level only, individual- + interpersonal-level, and individual- + interpersonal- + community-level interventions against an education-only control group. Data will be collected at six time points: baseline; 2, 4, and 6 months post baseline; and 12 and 24 months after intervention completion. Primary outcome is assessed by the Revised UCLA Loneliness Scale. Secondary outcomes include De Jong Gierveld Loneliness Scale, symptoms of anxiety and depression, perceived stress, life satisfaction, psychological well-being and sleep quality. Potential mediators will be assessed by mindfulness, self-compassion, emotion regulation, perceived social support, social network characteristics, and neighbourhood collective efficacy and identification. Analyses will follow the intention-to-treat principle, employing linear mixed-effects models, regression, mediation, and cost-effectiveness. Qualitative data collected via focus group discussions will be analysed thematically to gain deeper insight into participants' experiences and perceptions of the different interventions. Results: This study will last for 4 years, starting from June 2025 to May 2029. Recruitment and enrolment will begin in March 2026. Data collection will commence in April 2026, followed by the start of intervention delivery. Conclusion: To our knowledge, this is the first study globally to implement a multi-level intervention targeting older adults experiencing loneliness and poverty. If proven effective, the multi-level intervention will establish a foundation for community-wide implementation, providing a timely, affordable, and scalable approach that leverages community social capital. Clinical trial registration: ClinicalTrials.gov, identifier NCT07123064.