Background: Blood eosinophil (EOS) counts are critical to the accurate identification of asthma phenotypes. However, there are few long-term data on intraindividual EOS count variability among patients with eosinophilic asthma.
Objective: This post hoc analysis of 2 phase III clinical trials from the reslizumab BREATH program explored the variability of blood EOS counts in patients with eosinophilic asthma receiving placebo.
Methods: Pooled data from study participants receiving placebo (previously randomized 1:1 to receive reslizumab or placebo) were analyzed for blood EOS count variability over 52 weeks. EOS counts were measured up to twice during screening, every 4 weeks from randomization to the end of treatment and at the 90-day follow-up visit.
Results: Of 476 included patients, 31 (6.5%), 38 (8.0%), 55 (11.6%), and 352 (73.9%) patients had baseline blood EOS counts of <150, ≥150 to <300, ≥300 to <400, and ≥400 cells/μL, respectively. Patients frequently shifted between EOS count categories during the 52-week treatment period, most often moving to the highest EOS category. Among patients in each of the lower 3 EOS categories, 27% to 56% of patients shifted to the ≥400 cells/μL category at some point during the treatment period.
Conclusion: Intraindividual variability in blood EOS count was high among patients with eosinophilic asthma receiving placebo, with shifts to ≥400 cells/μL from lower categories frequently observed. Repeat determinations of blood EOS count may be important to ensure appropriate selection of therapy in patients with severe asthma.
Keywords: Asthma; EOS; Eosinophilia; Eosinophils; Placebo; Reslizumab; Variability.
Copyright © 2020 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.