Abstract
Introduction: Chronic obstructive pulmonary disease (COPD) is a heterogeneous respiratory condition characterized by chronic inflammation and exacerbations. Inhaled corticosteroids (ICS) are commonly prescribed to reduce exacerbation risk, yet their efficacy varies among patients. Emerging evidence suggests that blood eosinophil count may serve as a biomarker to predict ICS responsiveness in COPD patients.
Objectives: This study investigates the relationship between serum eosinophil counts and the effectiveness of ICS in reducing COPD exacerbation rates.
Patients and Methods: This prospective cohort study enrolled 430 COPD patients from two major pulmonology centers in Tehran, Iran, between May 2021 and November 2022. After obtaining written informed consent, demographic data and spirometry measurements were collected to classify COPD severity according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Venous blood samples were analyzed for eosinophil counts, categorizing patients into groups with counts below or above 300 cells/μL. Participants were followed for six months to record clinical outcomes, including mortality, hospitalizations, and outpatient visits related to COPD exacerbations. The study’s primary focus was to assess the impact of ICS on exacerbation rates stratified by eosinophil levels, aiming to evaluate eosinophil count as a biomarker for treatment responsiveness and to inform personalized COPD management.
Results: In a population of COPD patients who underwent ICS, the results indicated that patients with eosinophil counts higher than 300 cells/μL, compared to those with lower counts, demonstrated significantly fewer hospitalization rates (unadjusted B: -0.52 and adjusted B: -0.55). Similarly, the relationship between elevated eosinophil counts and outpatient visit frequency showed significant negative associations (unadjusted B: -1.82 and adjusted B: 1.88). However, in terms of six-month outcomes (recovery versus death), no statistically significant differences were observed between the two groups.
Conclusion: These findings suggest that blood eosinophil counts ≥300 cells/μL are associated with a pronounced reduction in severe COPD exacerbations among patients treated with ICS. This supports the use of eosinophil levels as a practical biomarker to guide ICS therapy, enabling more targeted, personalized treatment strategies that optimize clinical outcomes in COPD management.