Eosinopenia in Severe COPD Exacerbation

The goals of this observational study are to identify factors independently associated with admission eosinopenia in patients with a severe exacerbation of chronic obstructive pulmonary disease (COPD) and to determine when blood eosinophil count (BEC) will recover to baseline stable state in patients who are admitted to hospital with a severe exacerbation of COPD and associated eosinopenia. The main aims of the study are to: 1. Identify demographic, physiological and clinical factors independently associated with admission eosinopenia in patients with a severe exacerbation of COPD 2. Assess the time to recovery from eosinopenia to stable BEC following a severe exacerbation of COPD