Community-Based Health Promotion for Non-Communicable Disease Prevention in Sri Lanka: Protocol for the Happy Village Plus Cluster Randomized Trial

Background Non-communicable diseases (NCDs) drive major mortality, morbidity, and economic loss in low- and middle-income countries. In Sri Lanka, NCDs account for over 80% of premature deaths, with cardiovascular disease, cancer, and diabetes being the leading causes. Methods This protocol describes a cluster randomized trial of Happy Village Plus, a community-based NCD prevention program that builds on the ongoing Happy Village initiative launched in 2017. The intervention uses a multilevel package of individual, group, community, and policy-oriented strategies tailored to local needs. It applies an adaptive implementation structure that is refined through community feedback and is supported by mediation and advocacy to link communities with stakeholders. The core components include health education, behaviorally informed approaches, and skills development targeting key risk factors, diet quality, physical inactivity, tobacco use, and alcohol use. Preparatory activities included volunteer training, stakeholder engagement, and community mobilization. Discussion The evaluation comprised two components. The quantitative trial assessed behavioral outcomes, fruit and vegetable intake, sugar-sweetened beverage consumption, overall diet quality, cigarette use, physical inactivity, cardiometabolic outcomes, blood pressure, blood cholesterol, fasting blood glucose, body mass index, and waist circumference. A qualitative process evaluation examines implementation and context, including norms, perceptions, social network development, acceptability, feasibility, barriers, and facilitators. This trial will generate robust evidence on the effectiveness and implementation of an adaptive village-level health promotion model for NCD prevention in Sri Lanka, with relevance for scalable and equitable approaches in similar settings. Trial Registration The clinical trial registration number is SLCTR/2023/005 (19-03-2023).