The utility of inflammatory markers to predict readmissions and mortality in COPD cases with or without eosinophilia

BACKGROUND COPD exacerbations requiring hospitalization increase morbidity and mortality. Although most COPD exacerbations are neutrophilic, approximately 10%-25% of exacerbations are eosinophilic. AIM We aimed to evaluate mortality and outcomes of eosinophilic and non-eosinophilic COPD exacerbations and identify new biomarkers that predict survival. METHODS A retrospective observational cohort study was carried out in a tertiary teaching hospital from January 1, 2014 to November 1, 2014. All COPD patients hospitalized with exacerbations were enrolled in the study at their initial hospitalization and followed-up for 6 months after discharge. Electronic data were collected from the hospital database. Subjects' characteristics, hemogram parameters, CRP levels, neutrophil-to-lymphocyte ratio (NLR), platelet-to-mean platelet volume ratio on admission and discharge, length of hospital stay (days), readmissions, and mortality were recorded. Patients were grouped according to peripheral blood eosinophil (PBE) levels: Group 1, >2% PBE, eosinophilic; Group 2, non-eosinophilic ≤2%. Patient survival after hospital discharge was evaluated by Kaplan-Meier survival analysis. RESULTS A total of 1,704 patients hospitalized with COPD exacerbation were included. Approximately 20% were classified as eosinophilic. Six-month mortality was similar in eosinophilic and non-eosinophilic groups (14.2% and 15.2%, respectively); however, the hospital stay length and readmission rate were longer and higher in the non-eosinophilic group (P<0.001 and P<0.01, respectively). CRP and NLR were significantly higher in the non-eosinophilic group (both P<0.01). The platelet-to-mean platelet volume ratio was not different between the two groups. Cox regression analysis showed that survival was negatively influenced by elevated CRP (P<0.035) and NLR (P<0.001) in the non-eosinophilic group. CONCLUSION Non-eosinophilic patients with COPD exacerbations with high CRP and NLR values had worse outcomes than eosinophilic patients. PBE and NLR can be helpful markers to guide treatment decisions.