Stability of Blood Eosinophils in COPD with Multiple Acute Exacerbations Within 1 Year and Its Relationship with Prognosis

BACKGROUND: The relationship between increased blood eosinophils (EOS) and the prognosis of patients with chronic obstructive pulmonary disease (COPD) remains controversial. We aimed to explore the stability of blood eosinophils in patients with multiple hospitalizations for acute exacerbations of chronic obstructive pulmonary disease (AECOPD) over a 1-year period and its relationship with readmission rates and mortality. METHODS: Prospectively include patients with at least 2 hospitalizations for AECOPD in 1 year between June 2019 and December 2021. Using 150 cells/ul as the cut-off value, the study population was divided into EOS, non-EOS, and fluctuating groups based on the longitudinal stability of blood EOS. The relationship between blood EOS and readmission rate and mortality was analyzed according to the 6-month follow-up after hospital discharge. RESULTS: A total of 202 patients were included. 48, 108, and 46 patients were in the EOS, non-EOS, and fluctuating groups, respectively. The stability of blood EOS at 1 year was 77.2%. The risk of death was lower in the EOS group compared to the non-EOS group (HR=0.323, 95% CI 0.113–0.930, P =0.036). The risk of readmission was lower in both the EOS group (HR=0.486, 95% CI 0.256–0.923, P =0.027) and the non-EOS group (HR=0.575, 95% CI 0.347–0.954, P = 0.032) than in the fluctuating group. CONCLUSION: The blood EOS of COPD patients is relatively stable over 1 year. Patients with consistently high blood EOS had a lower risk of all-cause mortality after discharge; patients with fluctuating blood EOS had a higher risk of readmission.