Role of peripheral eosinophilia in acute exacerbation of chronic obstructive pulmonary disease

BACKGROUND Eosinophil counts are a promising guide to systemic steroid administration for chronic obstructive pulmonary disease (COPD). AIM To study the role of peripheral eosinophilia in hospitalized patients with acute exacerbation of COPD (AECOPD). METHODS From January 2014 to May 2017, patients with AECOPD hospitalized in Taipei Tzu Chi Hospital were retrospectively stratified into two groups according to their peripheral eosinophil count: The EOS group (eosinophil count >= 2%) and the non-EOS group (eosinophil count < 2%). Demographics, comorbidities, laboratory data, steroid use, length of hospital stay, and COPD-related readmissions were compared between the groups. RESULTS A total of 625 patients were recruited, with 176 patients (28.2%) in the EOS group. The EOS group showed a lower prevalence of infection, lower cumulative doses of prednisolone equivalents, shorter length of hospital stay, and higher number of COPD-related readmissions than the non-EOS group. There were significantly linear correlations between eosinophil percentage and number of readmissions and between eosinophil percentage and length of hospital stay (P< 0.001, Pearson's r = 0.147;P= 0.031, Pearson's r = -0.086, respectively). The EOS group and a lower percent-predicted value of forced expiratory volume in one second (FEV1) were associated with shorter time to first COPD-related readmission [adjusted hazard ratio (adj. HR) = 1.488,P< 0.001; adj. HR = 0.985,P< 0.001, respectively]. CONCLUSION The study findings suggest that the EOS group had the features of a shorter length of hospital stay, and lower doses of systemic steroids, but more frequent readmissions. The EOS group and lower percent-predicted FEV1 values were risk factors for shorter time to first COPD-related readmission.