Peripheral blood eosinophil counts in COPD patients and its relationship with prescription of inhaled corticosteroid in real world setting in Japan

Abstract

Background: Although recent retrospective studies suggest the possibility that peripheral blood (PB) eosinophil counts can predict the efficacy of inhaled corticosteroids (ICS) in COPD, the results are still inconsistent. In addition, the distribution of PB eosinophil counts and its relationship with prescription of ICS in real world settings has not been fully described. Aim: The aim of the current study is to clarify the distribution of PB eosinophil counts in real world settings in Japan. We also analyzed the relationship between eosinophil count and the serum IgE level and frequency of ICS prescription. Methods: The data from patients diagnosed as COPD based on GOLD document in Teikyo University hospital and followed by specialists were analyzed (n=103). Asthma patients were excluded by specialists. The PB eosinophil %, counts, serum IgE level and medications were analyzed during stable condition. Results: PB eosinophil (%) exceeded 2% and 5% of total white blood cell count in 72.8% and 22.3% of patients, respectively. PB eosinophil counts were more than 150/μl and 300/μl in 54.4% and 23.3% of patients, respectively. Although ICS was prescribed to 31.1% of patients, there was no significant relationship between eosinophil counts and the frequency of ICS prescription and serum IgE level. Conclusion: In majority of COPD patients, PB eosinophil % or counts exceeded 2% or 150/μl, respectively and did not seem to reflect the atopic status and affect the decision making for ICS prescription by specialists. Utility of PB eosinophil counts in COPD seemed to be limited and its role should be further investigated.