Clinical predictors and phenotypic associations of mucus plugging in moderate to severe asthma

Introduction: Mucus plugging (MP) is recognised as a contributory factor to airway obstruction and symptoms in persistent asthma. We aimed to determine clinical predictors and phenotypic associations of mucus plugging in moderate-to-severe asthma in a real-life clinic setting. Methods: MPs were identified by a thoracic radiologist on HRCT. A MP score (MPS) was subsequently calculated and analysed along with type 2 (T2) biomarkers, spirometry, severe exacerbations and asthma control for 126 moderate to severe asthma patients. Results: Asthma patients with MP had significantly worse FEV₁%, FEF_25-75% and FEV₁/FVC; higher levels of peripheral blood eosinophils, fractional exhaled nitric oxide, total IgE and A. fumigatus IgE titres associated with more frequent severe exacerbations. Adjusted odds ratios (95%CI) for prediction of MP were as follows: FEV₁/FVC 3.01(1.14,7.97); ≥2 exacerbations/yr 5.00(1.55,16.11); blood eosinophils 3.23(1.16,8.96); total IgE 3.20(1.09,9.37); and A. fumigatus IgE titres 9.37(1.82,48.20). Conclusion: Poorly controlled asthma patients with MP exhibited significantly worse airflow obstruction, greater T2 inflammation associated with more frequent severe exacerbations. Spirometry, exacerbations, blood eosinophils, total IgE and A. fumigatus IgE were identified as real-life clinical predictors of MP. *p<0.05; **p<0.01 and ***p<0.001. Means±SD or median(IQR) presented.