Structural heat adaptation and education in urban settings (SHAPES trial): study protocol for a cluster randomised controlled trial

BACKGROUND: Extreme heat events are intensifying worldwide due to climate change, posing significant health risks and economic challenges. The urban heat island effect poses extra challenges to the inhabitants of cities, especially in the global South. METHODS: This trial aims to evaluate the effectiveness of a comprehensive resilience and heat adaptation bundle (ReHAB) that integrates behavioural and structural interventions to reduce heat-related morbidity and mortality and improve internal ambient conditions in urban settings of Pakistan. This would be a cluster randomised controlled trial where 22 clusters comprising approximately 70-80 households per cluster will be randomly assigned to intervention and control arms in a 1:1 ratio. The intervention ReHAB is a combination of community education and awareness and targeted structural modifications, including reflective paints, shading, sustained energy/power, improved ventilation, and community shaded spaces. Data on health and behaviours will be collected via wearable devices and household surveys and environmental sensors will be used to capture indoor and outdoor thermal conditions. EXPECTED OUTCOMES: The findings from this trial will provide evidence for the effectiveness of the ReHAB bundle on indoor ambient environments and health and help policy recommendations for urban areas, especially for the global south. ETHICS AND DISSEMINATION: The study has received ethical approval from the Aga Khan University (AKU) (Ref: 2025-11548-35626) and the Pakistan National Bioethics Committee (Ref: 4-87/NBCR-1065/23/1736). Written informed consent will be obtained from all participants before enrolment. Referral pathways to healthcare facilities will be established to ensure timely management of complications. Findings will be disseminated through peer-reviewed publications, scientific conferences and engagement with policymakers and public health stakeholders. Results will also be shared with participants and communities through meetings and informal sessions to raise awareness and support evidence-based heat adaptation. TRIAL REGISTRATION NUMBER: NCT06991543.