Fungal Sensitization and the Manifestation of Asthmatic Features in Chronic Obstructive Pulmonary Disease

Objective Fungal sensitization is known to be prevalent in chronic obstructive pulmonary disease (COPD) and it is recognized as a risk factor for severe asthma. However, its relationship to the development of asthmatic features in COPD remains unclear. Because the diagnostic criteria for asthma-COPD overlap (ACO) are not standardized, we focused on the specific asthmatic features that form the diagnostic basis of ACO, namely, blood eosinophilia and recurrent wheezing, to clarify how fungal sensitization contributes to their manifestation in COPD. Methods We retrospectively analyzed data from 72 patients with COPD who had specific immunoglobulin E (IgE) levels measured at the Tokyo Medical University Hospital between October 2019 and January 2024. The associations between fungal sensitization and clinical features, including the blood eosinophil count and recurrent wheezing, were analyzed. Results Fungal sensitization was observed in 38% of patients. Patients with fungal sensitization had significantly higher blood eosinophil counts than those without fungal sensitization, whereas no significant differences were found for other aeroallergens. Moreover, fungal sensitization was independently associated with both an elevated blood eosinophil count [≥300 cells/mm³; odds ratio (OR) 3.51, 95% confidence interval (CI) 1.21-10.20] and recurrent wheezing (OR 6.93, 95% CI 1.86-25.80). Conclusion Fungal sensitization was independently associated with an elevated blood eosinophil count and recurrent wheezing in patients with COPD. These findings suggest that fungal sensitization may play a biological role in the emergence of the asthmatic features that characterize the ACO phenotype in COPD.