Blood eosinophils and outcomes in severe hospitalised exacerbations of COPD

BACKGROUND: Patients with moderate exacerbations of chronic obstructive pulmonary disease (COPD) and the eosinophilic phenotype have better outcomes with prednisolone. Whether this is the case in patients hospitalised with a severe exacerbation of COPD is unclear. We investigate the rate of recovery of eosinophilic and non-eosinophilic exacerbations from subjects participating in a multi-centre randomised control trial assessing health outcomes in hospitalised exacerbations (clinical trial registration ISRCTN05557928). METHODS: Subjects were recruited at presentation to hospital with an exacerbation of COPD and stratified into eosinophilic exacerbations if the peripheral blood eosinophil on admission was ≥200 cells/μL and/or ≥2% of the total leukocyte count. Admission details, serum CRP, length of stay and subsequent re-hospitalisation were compared between groups. RESULTS: We recruited 243 COPD subjects (117 males) with a mean age (range) of 71 years (45-93). The inpatient mortality rate was 3% (median time to death 12 days, range 9-16). The median absolute eosinophil count was 100 cells/μL (range 10 to 1500 cells/μL) and 25% met our criteria for an eosinophilic exacerbation. In this population, the mean length of stay was shorter than in patients with non-eosinophilic exacerbations (5.0 (1-19) vs. 6.5 (1-33), p=0.015) following treatment with oral corticosteroids and independent of treatment prior to admission. Readmission rates at 12 months was similar between the groups. CONCLUSIONS: Patients presenting to hospital with a severe eosinophilic exacerbation of COPD have a shorter length of stay. These exacerbations are usually not associated with an elevated CRP, suggesting that better treatment stratification of exacerbations can be utilised.