Respiratory functional phenotypes of severe asthma in cohort of 130 patients

Abstract

Asthma is a heterogeneous disease divided into clusters that do not consider the type of respiratory functional impairment. The objective was to investigate the association between respiratory functional impairment and main asthma phenotypes. We conducted a retrospective, observational, monocentric study including patients with severe asthma who first consulted at Croix Rousse Hospital, Hospices Civils de Lyon, between January 2015 and June 2018. Patients were divided into 4 respiratory functional groups: reversible proximal airway obstruction (Group 1); fixed proximal airway obstruction (Group 2); exclusive small airway involvement (Group 3); no functional impairment (Group 4). The distribution of these 4 functional groups was analyzed within the main clinical and biological phenotypes of severe asthma: TH2 high allergic, TH2 high eosinophil, mixed TH2 allergic/eosinophil, hypersensitivity to aspirin, and TH2 low. Among 130 patients, 28 patients were included in group 1 (22%), 51 patients in group 2 (39%), 27 patients in group 3 (21%), and 24 patients in group 4 (18%). The distribution of clinical phenotypes was significantly different between the groups (p=0.004). TH2 high eosinophil phenotype patients were higher in groups 1 and 2, compared to other phenotypes (p=0.014), and TH2 allergic phenotype patients were higher in groups 3 and 4, compared to other phenotypes (p=0.0003). Other phenotypes of severe asthma were not associated with a respiratory functional signature. We found heterogenous pulmonary functional impairment in severe asthma. Some functional characteristics are associated to allergic and eosinophilic phenotypes. More studies are needed to determine prognostic or therapeutic value of the functional impairment.