Allergic Sensitization and Serum Immunoglobulin E in Eosinophilic COPD

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.

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.

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.

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.