The INTERvening for LUNG Health Trial

Chronic respiratory diseases (CRDs), including asthma, chronic obstructive pulmonary disease (COPD), and chronic bronchitis, represent a major global health challenge, accounting for over 455 million cases and 4 million deaths annually, with the greatest burden in low- and middle-income countries (LMICs). INTERvening for LUNG health (INTERLUNG) is a 40-month randomized controlled trial in Bhaktapur, Nepal, aimed at evaluating a multi-component, community health worker (CHW)-driven intervention for CRD prevention, targeting both environmental and infectious risk factors. The intervention integrates tobacco prevention (education, peer support, nicotine replacement therapy, quit lines), reduction of indoor and ambient air pollution (HEPA purifiers, vacuum cleaners, N95 masks for high pollution days), infectious risk mitigation (annual influenza vaccination and a one-time pneumococcal vaccination, surgical mask use during viral seasons or household illness, and handwashing support), and promotion of physical activity. Human-centered design (HCD) workshops and in-depth interviews with community members, healthcare practitioners, government officials, and multilateral organizations conducted in 2025 and early in 2026 informed adaptation to local context, addressing key implementation factors such as partner and community engagement, compatibility, and resource availability. Eight hundred index participants aged 9 years with impaired lung function (10th percentile or lower in FEV1/FVC Z-score) and chronic respiratory symptoms, along with household members, will be randomized to intervention or usual care, with outcomes assessed at 40 months. Clinical outcomes include improvements in lung function (primary outcome) and respiratory health-related quality of life (St. Georges Respiratory Questionnaire); secondary outcomes encompass implementation metrics such as adoption, acceptability, appropriateness, fidelity, and scalability, evaluated through mixed methods including surveys, adherence monitoring, and qualitative interviews. The project leverages a multidisciplinary team with extensive experience in CRD research, implementation science, and community-based interventions in Nepal, and builds on robust infrastructure for population health research and environmental monitoring. By integrating evidence-based strategies for tobacco control, air pollution reduction, vaccination, and physical activity promotion into a scalable CHW-driven model, INTERLUNG addresses critical gaps in CRD prevention and management in LMICs, aligns with global health priorities and Sustainable Development Goals, and provides a framework for future scale-up and policy integration. The anticipated impact includes improved lung function trajectories and quality of life for at-risk populations, enhanced health system capacity for chronic disease management, and generation of actionable data to inform broader implementation of multi-component respiratory health interventions in urban LMIC settings. The intervention is adaptable for both children and adults, reflecting a life-course approach. It also addresses the need for culturally relevant education and training for primary healthcare staff. The inclusion of environmental monitoring and objective adherence measures (e.g., air quality sensors, pedometer logs) will strengthen outcome assessments and inform best practices for future implementation. By focusing on both clinical effectiveness and implementation outcomes, INTERLUNG will provide critical insights into the feasibility, acceptability, and scalability of comprehensive CRD interventions in resource-limited urban settings. The results are expected to inform national and regional policy, support integration into universal health coverage packages, and contribute to the global evidence base for CRD prevention and management in LMICs. Ultimately, INTERLUNG aims to reduce the burden of CRDs, improve respiratory health equity, and advance sustainable health system strengthening in Nepal and similar contexts.

Inclusion criteria

• Age ≥9 years at enrollment.
• Resident of the Bhaktapur district and member of a household willing to participate in study procedures.
• Pre-bronchodilator FEV1/FVC at or below the 10th percentile (Z-score ≤ -1.28) based on Global Lung Function Initiative reference equations.
• Presence of at least one respiratory risk factor, including:
• usual cough or phlegm, wheezing in the past 12 months, self-reported prior pulmonary tuberculosis, physician-diagnosed asthma, ever smoking, or occupational exposure to dust or smoke.
• Willing and able to provide written informed consent (or assent with parental/guardian permission for participants <18 years).
• Willing to participate in study assessments and follow-up visits during the 40-month study period.

Exclusion criteria

• Medical condition that precludes safe performance of spirometry.
• Acute respiratory illness at the time of enrollment that would prevent reliable baseline spirometry testing.
• Plans to move out of the study area during the follow-up period. Inability or unwillingness to comply with study procedures or follow-up visits.
• Any other condition that, in the opinion of the investigators, would interfere with participation or interpretation of study results.

Household members:

• Household members of enrolled index participants may participate in certain assessments and receive selected intervention components if the index participant is randomized to the intervention arm and provides informed consent or assent.