Elevated Peripheral Blood Eosinophils during Acute Exacerbation of Chronic Obstructive Pulmonary Disease Prevalence and clinical significance

Objectives: This study aimed to evaluate the prevalence and clinical significance of elevated peripheral blood eosinophil (PBE) counts in hospitalised patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in Oman. An elevated PBE count during AECOPD is a potential predictor of treatment responsiveness and future exacerbation risk. Methods: This single-centre retrospective study included all patients with AECOPD who were admitted to Sultan Qaboos University Hospital, Muscat, Oman, between January 2017 and July 2019. The patients were classified as having eosinophilic or non-eosinophilic AECOPD based on blood eosinophil counts. An elevated eosinophil count was defined as a blood eosinophil count >0.3 × 10⁹ cells/L on admission. The length of hospital stay, use of oral and inhaled steroids, number of readmissions in a year and use of mechanical ventilation on admission were compared between the eosinophilic and non-eosinophilic AECOPD groups. Results: Of the 102 patients included in the study, 42.2% had eosinophilic AECOPD. The eosinophilic AECOPD group had a reduced length of hospital stay (P = 0.02) but an increased risk of readmission in a year (P = 0.04). Most patients in both groups were treated with inhaled and oral steroids. The need for mechanical ventilation did not differ between the groups. Conclusion: Eosinophilia is highly prevalent in patients with AECOPD and is associated with a reduced length of hospital stay but an increased risk of readmission in a year. It can be used as a surrogate marker to predict the health outcomes of patients with AECOPD and select treatment options.