Abstract Rationale Since the original description by Churg and Strauss in 1951 of 13 patients with peripheral eosinophilia, fever and necrotizing vasculitis, severe asthma is considered essential to the diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA). We examined the prevalence of the physiological abnormality of asthma in the presence of airway eosinophilia in patients with EGPA. Methods A retrospective analysis was conducted on data of patients meeting the American College of Rheumatology criteria for EGPA from February 2015 to October 2025. The physiologic and inflammatory measurements for airway disease, including spirometry, bronchodilator responsiveness testing, methacholine challenge testing, fractional exhaled nitric oxide (FeNO), quantitative sputum cytometry, and sinus evaluation, were performed as part of standard clinical care. All data were recorded in electronic case record forms without identifiers. All statistical analyses were performed using GraphPad Prism Version 10.5.0. Results Among 103 patients with a diagnosis of EGPA (median age 58 ± 21 years; 55% female), 69 (67%) demonstrated clinical or histologic evidence of vasculitis. Thirty-six (35%) were antineutrophil cytoplasmic antibody (ANCA)-positive, including 31 (30%) with anti-myeloperoxidase and 7 (7%) with anti-proteinase 3 specificity. The median peak blood eosinophil count was 5.3 ± 12 × 109/L. Objective assessment of asthma was available in 73 (71%) patients, and induced sputum analysis was performed in 57. Among these, 42 (74%) exhibited sputum eosinophilia 3% (median peak sputum eosinophils 32 ± 39%), despite treatment with high-dose inhaled corticosteroids or systemic prednisone. Notably, 14 (33%) of the 42 patients with sputum eosinophilia lacked objective evidence of asthma (PC20 methacholine 8 mg/mL or absence of bronchodilator responsiveness 200 mL and 12%. Sinus polyposis, ANCA positivity, and sputum eosinophilia were associated with raised FeNO of 35 ppb. Conclusion Airway eosinophilia (sputum eosinophils 3%) and not necessarily physiological abnormality of asthma may be sufficient to diagnose EGPA when associated with peripheral eosinophilia and tissue eosinophilic infiltration with or without vasculitis. This abstract is funded by: None
Thawanaphong et al. (2026) studied this question.