Eosinophils in COPD Exacerbations Are Associated With Increased Readmissions

BACKGROUND: A subset of patients with COPD demonstrates eosinophilic inflammation either in their sputum or blood. Previous studies regarding the association between increased blood eosinophil levels and poor readmission outcomes are conflicting. The goal of this study was to investigate outcomes following severe COPD exacerbations in patients with higher blood eosinophil levels. METHODS: With an observational study design, data on hospitalizations for severe COPD exacerbation were retrospectively gathered. Patient health data previous to and up to 1 year following the index hospitalization were included. Patients were stratified into the eosinophilic group if the blood eosinophil level on admission was >= 200 cells/mL and/or >= 2% of the total WBC count. Clinical outcomes were 12-month COPD-related readmission, 12-month all-cause readmission, length of stay, and time to COPD-related readmission. These outcomes were analyzed by using logistic, negative binomial, and Cox regression models. RESULTS: A total of 167 patients were included; 55 had eosinophilia. Eosinophilia was associated with an increased risk of 12-month COPD-related readmission (OR, 3.59 [95% CI, 1.65-7.82]; P = .0013), an increased risk of 12-month all-cause readmission (2.32 [95% CI, 1.10-4.92]; P = .0277), and a shorter time to first COPD-related readmission (hazard ratio, 2.74 [1.56-4.83]; P = .0005). The length of stay was not statistically different between eosinophilic and noneosinophilic patients. Sensitivity analyses using different eosinophilia definitions revealed a proportional increase in effect size with increasing eosinophil cell count definitions for predicting 12-month readmissions. CONCLUSIONS: Blood eosinophil levels can be used as a biomarker in severe COPD exacerbations for predicting higher readmission rates.