PUB - Publikationen an der Universität Bielefeld

Background Bronchodilator reversibility is a diagnostic criterion for asthma. However, patients with asthma may exhibit irreversible obstruction for various reasons including long-standing uncontrolled disease with airway remodeling or beta-2 receptor down-regulation caused by frequent use of inhaled short acting beta2-agonist (SABA). Aim This study aims to describe frequency of negative bronchodilator reversibility in patients with severe asthma and associations with other phenotypic characteristics. Methods Bronchodilator testing was performed according to guideline recommendations, with patients being advised to pause asthma and other interfering treatments before testing. Significant bronchodilator reversibility was defined as FEV1 increase > 200ml AND > 12% upon testing with SABA and/or short-acting muscarinic antagonist (SAMA). Results Bronchodilator reversibility results were available from 793 of the 2013 patients included in the GAN registry. Hereof, 250 (31.5%) had significant reversibility, while 543 (68.5%) were classified irreversible. Comparing patients with reversible and irreversible obstruction, sex (52% vs 56%), mean age (49.6 vs 50.0 years), smoking history (non: 57.2% vs 56.1%; active: 2.8% vs 2.2%; ex: 40% vs 41.7%), COPD comorbidity (5.2% vs 7.2%) and BMI (27.2 vs 27.5kg/m2) were similar in both groups. Comorbidities significantly associated with irreversible obstruction were: gastro-esophageal reflux (GERD), eosinophilic granulomatosis and polyangiitis (EGPA) and history of sinus surgery (p<0.05). Patients with reversible obstruction reported dyspnea at rest (27% vs 16%) and chest tightness (36% vs 26%) more frequently, had more severe obstruction at baseline (FEV1: 56% pred. vs. 64% pred.) and higher median FeNO levels (41ppb vs 33ppb, all p<0.05), while diffusion capacity did not differ (70% vs 71%). Conclusion In this real-life setting the majority of patients with severe asthma exhibited negative bronchodilator reversibility. Irreversible obstruction was associated with lower FeNO levels and history of GERD, EGPA and sinus surgery.