Allergic Sensitization and Serum Immunoglobulin E in Eosinophilic COPD.

BACKGROUND: Eosinophilic chronic obstructive pulmonary disease (COPD), is marked by type 2 inflammation, affects more than one-third of people with COPD, and is linked to exacerbation risk and corticosteroid responsiveness. The prevalence and clinical significance of allergic sensitization and elevated immunoglobulin E (IgE) in this subtype are not well understood. METHODS: We analyzed baseline data from 174 former smokers with eosinophilic COPD enrolled in a randomized trial. Participants underwent skin prick testing for 14 regional aeroallergens and total serum IgE measurement. Allergic sensitization was defined as ≥1 positive skin test; elevated total IgE as ≥100 IU/mL. We evaluated the prevalence of sensitization and elevated IgE, their overlap with asthma and seasonal allergies, and associations with self-reported allergen exposures. Logistic regression assessed links between atopic conditions, exposures, and sensitization. We also examined associations with COPD-related hospitalizations in the past year. RESULTS: Among participants (mean age 71.5 years; FEV₁% predicted 53.0%), 47.1% had allergic sensitization, 32.5% had elevated IgE, and 55.7% had allergic sensitization or elevated IgE. Seasonal allergies and asthma were reported by 59.8% and 43.7%, respectively. Among those without concomitant asthma, 38.8% had allergic sensitization. Cat ownership was associated with cat allergen sensitivity (OR=3.1, 95%: CI 1.1-8.6). Asthma and IgE were associated with sensitization to multiple allergens. Sensitization and IgE were not associated with prior-year COPD hospitalization. CONCLUSION: Allergic sensitization and elevated IgE are common in eosinophilic COPD, even without comorbid asthma. These findings support further research into the role of environmental allergens in disease progression and management.