Non-communicable diseases (NCDs) cause 4.7 million deaths annually in India. Floods increasingly disrupt NCD care, especially in Bihar, one of India’s most flood-prone and socioeconomically disadvantaged states. This study aims to strengthen the capacity of the community and primary healthcare systems to improve NCD outcomes during annual flooding in Bihar. We describe a type II, hybrid implementation-effectiveness parallel cluster randomised controlled trial with an embedded qualitative process evaluation. A multi-component, co-developed intervention targeting primary care and community settings will be implemented and evaluated over two flood seasons in 26 flood-prone community development blocks in three districts of Bihar. Normalisation Process Theory (NPT) will guide the interpretation and adaptation of the intervention for broader applicability. Data will be collected through baseline and follow-up cross-sectional surveys conducted immediately after and 6 months following each annual flood season. Mixed-methods implementation and effectiveness outcomes will be evaluated using the RE-AIM-QuEST (Reach, Effectiveness, Adoption, Implementation, and Maintenance, Qualitative Evaluation for Systematic Translation) framework. Co-primary outcomes are patient medication adherence and availability of a flood-proof kit with medication and clinical handover information during floods. A preliminary health economic evaluation will estimate the cost-effectiveness of the intervention from a healthcare and societal perspective, with and without the use of early-warning flood forecasting. The FUSION (Floods, UnderStanding clImate change and nON communicable disease) trial will generate evidence on effective and scalable strategies to enhance health system and community resilience for the continuity of NCD care during recurrent flooding in India. Findings will inform public health policy and disaster preparedness efforts in similar resource-constrained, climate-vulnerable settings. CTRI/2025/07/092055 Registered on 30/07/2025 http://www.ctri.nic.in/Clinicaltrials/pmaindet2.php?trialid=138142; ISCTRN18019775 Registered on 12/08/2025 https://www.isrctn.com/ISRCTN18019775
Manaseki-Holland et al. (2026) studied this question.