Data Collection and Harmonization in Preterm Respiratory Research: Recommendations and Insights From PELICAN.

INTRODUCTION: Individuals born preterm (before 37 weeks' gestation) have an increased risk of developing lung disease compared with those born at term. However, life-long lung function trajectories and the factors influencing them remain insufficiently understood in this population, reflecting an unfortunate scarcity of data, substantial heterogeneity in findings, and variability across centers. The Prematurity's Effect on the Lungs in Children and Adults Network (PELICAN) was established in 2020 as a Clinical Research Collaboration of the European Respiratory Society, with a key aim to develop the first harmonized global repository of demographic, clinic and lung function data from existing datasets on individuals born preterm. METHODS: Eligible datasets for inclusion were identified through three systematic literature reviews. A scientific steering committee was convened and organized into sub-groups, which undertook a consensus-based variable selection and data harmonization exercise. Data contributors uploaded data to a secure online portal, where further harmonization was applied. RESULTS: As of June 2026, the PELICAN data repository includes 20 datasets representing 14 countries and 3,388 individuals born preterm. PELICAN collects 142 variables, of which 96 have been fully harmonized across all contributing datasets, and 42 partially harmonized. Four variables could not be harmonized. CONCLUSIONS: In this paper, we describe the PELICAN collaboration, outline key challenges and successes encountered during data harmonization, and report data availability to date. This work represents an important step towards understanding the respiratory consequences of preterm birth and could inform the development of a Core Outcome Set for future data collected in this area.