Severe asthma phenotypes and endotypes

Introduction . Severe asthma is a heterogeneous disease with several phenotypes and endotypes. However, little is known about frequency of severe asthma phenotypes and endotypes in Russia. Aim . To assess frequency of severe asthma phenotypes and endotypes compared with mild/moderate asthma. Materials and methods . Cross-sectional single center study included 643 adult outpatients with mild/moderate asthma and 314 patients with severe asthma (SA) aged 18-90 years. Spirometry and bronchodilator reversibility testing were carried out. Fractional exhaled nitric oxide (FeNO) was measured by a chemiluminescent analyzer (logan 4100, UK). Hypersensitivity to common inhalant allergen was assessed by skin prick and blood specific IgE level. Peripheral blood eosinophil counts were measured by automatic analyzer. Asthma control and asthma-related quality of life were assessed by using ACQ-5 and SGRQ. Results . Allergic phenotype was more frequent in patients with mild/moderate asthma than in those with SA, but aspirin- induced asthma, steroid-dependent asthma, asthma with persistent airflow limitation and concomitant COPD, asthma with late onset and obesity were more frequent in SA. The majority of patients with SA had several phenotypes (mean 3 phenotypes) and at least one marker of T2-high endotype. Conclusion . The most frequent phenotypes of SA were allergic, with persistent airflow limitation, with concomitant obesity and COPD. Occurrence of asthma phenotypes differed between patients with SA and mild/moderate asthma. The majority of SA patients have T2-endotype.