Blood eosinophilia as a marker of early and late treatment failure in severe acute exacerbations of COPD.

•Adjusted: Eosinophilia in AECOPD is associated with a better prognosis on the short term but a worse prognosis on the long term.•Patients with eosinophilia ≥4% had a higher treatment failure rate (day 10–30) compared to patients with eosinophilia ≥2%–4%.•Despite pre-treatment with corticosteroids, Eosinophilia in peripheral blood remains a strong prognostic biomarker in patients with AECOPD.