INTRODUCTION: The eosinophilic phenotype of chronic obstructive pulmonary disease (COPD) has been demonstrated to respond better to corticosteroids and associated with better outcomes. This review aims to clarify the correlation of blood eosinophilia and outcomes patients with COPD exacerbations.

METHODS: This is a review of cohorts and case-control studies that looked into eosinophilia and outcomes in exacerbations using the meta-analysis of observational studies in epidemiology (MOOSE) guidelines. The primary study outcome was length of hospitalization; other outcomes include readmission and mortality rate within one year, in-patient mortality, and need for mechanical ventilation.

RESULTS: Six studies were included in the review. Patients with blood eosinophilia had significantly shorter hospital stay compared to non-eosinophilic patients (mean difference 0.68 days [95% CI 1.09,0.27]). Eosinophilic patients had significantly less frequent readmissions (OR 0.69 [95% CI 0.55,0.87]) but there was no statistically significant difference in the one-year mortality rate (OR 0.88 [95% CI 0.73, .06]). Analysis showed a trend toward lower in-patient mortality among eosinophilic patients (OR 0.53 [95% CI 0.27,1.05]). Furthermore, COPD patients with eosinophilia had significantly less need for mechanical ventilation during an exacerbation (OR 0.56 [95% CI 0.35,0.89]).

CONCLUSION: COPD patients with blood eosinophilia had significantly shorter hospital stay, less frequent readmissions, and are less likely to require mechanical ventilation compared to the non-eosinophilic phenotype.