Refractory asthma phenotyping based on immunoglobulin E levels and eosinophilic counts: A real life study

Abstract

Background: Asthma is an inflammatory heterogeneous disease with variable severity. The serum IgE level and Eosinophilic count have been used as biomarkers to define treatment strategies with biological agents in severe refractory asthma.

Objective: The aim of this study is to determine the concurrence of high eosinophil count and elevated serum IgE levels in patients with severe refractory asthma.

Methods: A retrospective cross-sectional real-life study was conducted on patients attending adult refractory asthma outpatient clinic between 2015 and 2018. Serum total IgE level and blood EOS count on matched dates with spirometry and Asthma Control Test (ACT) scores were collected. All data were obtained while patients were not on biological agents.

Results: A total of 142 patients with severe refractory asthma were included. The mean age was 43 years, mean eosinophilic count 564 cells/μL and mean serum IgE levels of 520 IU/ml. There was a significant correlation between serum IgE level and eosinophilic count. Serum IgE and eosinophilic count were concurrently elevated in 110 patients (78%). The patients were further categorized into four subgroups. Group A: IgE 30-100 IU/mL and EOS 150-300 cells/μL (7.3%), Group B: IgE >100 IU/mL and EOS 150-300 cells/μL (19.1%), Group C: IgE 30-100 IU/mL and EOS >300 cells/μL (14.5%) and Group D: IgE >100 IU/mL, EOS >300 cells/μL (59.1%).

Conclusion: The majority of severe refractory asthma patients exhibits both elevated serum IgE level and eosinophilic counts.

Keywords: Anti IL-5; Asthma control test (ACT); Biological therapy; Eosinophils; IgE; Immunoglobulin E; Real life; Refractory asthma; Severe asthma; anti-IgE.