The association between airway and systemic eosinophilia and symptoms and exacerbations differ between asthma and COPD patients

Abstract

Background: Eosinophilic asthma and COPD endotypes have been associated with increased exacerbation risk and symptom burden. We aimed to study the difference between airway and systemic eosinophilia in terms of clinical outcomes for both asthma and COPD. Methods: BREATHE is a real-life study assessing biomarkers and disease mechanisms in asthma and COPD patients. Symptoms were assessed using ACQ-5 and CAT scores. Blood eosinophilia was defined as >0.3x109 cells/L, sputum eosinophilia as ≥3%, and blood+sputum eosinophilia as both. Results: In asthma patients, ACQ-5 and CAT scores were higher in patients with elevated blood and sputum (2.47 and 14.24) and elevated sputum (1.84 and 13.19) eosinophils compared to blood (1.37 and 10.30) eosinophils (p For asthma and COPD patients, exacerbations during the previous year were more frequent in patients with elevated sputum and blood+sputum eosinophils (asthma: p=0.001; COPD: p=0.015). Conclusion: Asthma, but not COPD, patients with sputum eosinophilia (regardless of co-expression of blood eosinophilia) have more symptoms than those with blood eosinophilia alone. Eosinophilia in sputum may be a stronger predicter for exacerbations than blood eosinophilia in both COPD and asthma patients.