This was an observational multicenter study. 210 patients with stable COPD, GOLD grades II to IV were enrolled. Concordance was defined as blood eosinophil values persistently lower than or persistently higher than the absolute cutoff points of 150 cells/μL and 300 cells/μL, or the percentage cutoff points of 2%, 3%, and 4%. Discordance was obtained when the blood eosinophil values varied between any two visits. ICS treatment data were recorded at one time point at the inclusion of the study.
210 patients were recruited and 2059 visits were recorded. Most of them were receiving ICS at the entry [81%]. Using as cuttoff values the percentages of 2,3 and 4% eosinophils a discordance of 77, 60 and 42% was observed. Similar results were observed for the absolute counts. The above discordance was higher for the stable disease as compared to both exacerbations and hospitalizations. The authors finally concluded that that blood eosinophil levels present significant variability throughout the course of COPD, and a single measurement may therefore not be a reliable predictor of ICS response.
The study raised an important point which is the lack of stability for blood eosinophils.Using the current data we cannot draw conclusions regarding ICS responses. It is crucial to have a large randomized study in order to confirm whether blood eosinophils could guide treatment strategies based on ICS. In the meanwhile we have to define the specific cutoff values which clearly characterize the systemic eosinophilia in patients with COPD.