Implication of Admission Eosinophil Count and Prognosis of Coronavirus Disease 2019 (COVID‐19) in Elderly Patients With COPD: A Territory‐Wide Cohort Study

Abstract

<h3>Objectives</h3><p>This study aims to investigate the association between elderly patients with COPD with different blood eosinophil on admission and those without COPD and the prognosis of COVID-19.</p><h3>Method</h3><p>A territory-wide retrospective study was conducted to investigate the association between elderly COPD patients with different blood eosinophil on admission and the prognosis of COVID-19. Elderly patients admitted to public hospitals and community treatment facility in Hong Kong for COVID-19 from January 23, 2020, to September 31, 2021, were included in the study. Severe diseases were defined as those who develop respiratory complications, systemic complications and death.</p><h3>Results</h3><p>Among the 1925 patients included, 133 had COPD. Forty had admission blood eosinophil count ≥ 150 cells/μL, and 93 had blood eosinophil count < 150 cells/μL. Patients with COPD and admission blood eosinophil count ≥ 150 cells/μL, but not those with admission blood eosinophil count < 150 cells/μL, had severe COVID-19 with the development of respiratory and systemic complications. They were more likely to develop respiratory failure (OR = 5.235, 95% CI = 2.088–13.122, <em>p</em> < 0.001) and require invasive mechanical ventilation (OR = 2.433, 95% CI = 1.022–5.791, <em>p</em> = 0.045) and intensive care unit admission (OR = 2.214, 95% CI = 1.004–4.881, <em>p</em> = 0.049).</p><h3>Discussion</h3><p>Our study suggested that the blood eosinophil count on admission could have significant prognostic implications among elderly patients with COPD. Patients with COPD and admission blood eosinophil count ≥ 150 cells/μL, but not those with admission blood eosinophil count < 150 cells/μL, have significantly increased risks of developing respiratory and systemic complications from COVID-19, when compared with non-COPD patients.</p>