BASE: Bronchiectasis Severity and Exacerbation Risk Study

Non-cystic fibrosis bronchiectasis (NCFB) is a chronic airway disease characterized by permanent bronchial dilatation, impaired mucus clearance, recurrent infection, airway inflammation, and repeated exacerbations. Existing bronchiectasis severity tools are clinically useful, but many depend on prior exacerbation history, hospitalization history, subjective symptom assessment, or culture-based microbiological classification.

This prospective observational cohort study aims to develop and validate the Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework. BASE is designed to classify current bronchiectasis severity and predict 12-month exacerbation risk using objective baseline functional, radiological, oxygenation, and inflammatory variables. Detailed methodological specifications, including variable definitions, scoring architecture, endpoint hierarchy, development-validation governance, and analytical integrity rules, are archived in a restricted-access Zenodo record: https://doi.org/10.5281/zenodo.20143505

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Participants will receive routine clinical care, and no treatment or intervention will be assigned by the study protocol. Patients will be followed for 12 months to record bronchiectasis exacerbations, hospitalization, lung-function change, inflammatory marker change, and clinical outcomes. The Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework includes two linked baseline models: the BASE Severity model (BASE-S) for current bronchiectasis severity classification and the BASE Prognostic model (BASE-P) for prediction of 12-month exacerbation risk. Both models will be derived in the development cohort and applied unchanged to the validation cohort.