Beyond Eosinophilia: A Dual Eosinophil Phenotype Model in Bronchiectasis

Background and Objectives: Bronchiectasis exhibits heterogeneous inflammatory features. Although peripheral blood eosinophil counts guide therapy in other airway diseases, their role in phenotyping bronchiectasis remains under-defined. We investigated the clinical, microbiological, and inflammatory profiles of eosinopenic and eosinophilic phenotypes based on stable-state blood eosinophil counts. Materials and Methods: This retrospective cohort study evaluated 163 patients diagnosed with bronchiectasis between December 2020 and October 2024. Patients were stratified into three groups based on stable-state peripheral blood eosinophil counts: eosinopenia (≤100 cells/µL), intermediate eosinophil levels (101–299 cells/µL), and eosinophilia (≥300 cells/µL). Baseline demographics, comorbidities, laboratory data, sputum culture results, radiological scores, and clinical outcomes were compared. Factors associated with exacerbations were evaluated using multivariable logistic regression.