BREATHE – Distribution and co-expression of T2 biomarkers in asthma and association with severity, clinical characteristics and co-morbidities

<b>Background:</b> Asthma is a complex disease characterized by airway inflammation associated with type 2 inflammation in many patients. Eosinophils play a pivotal role in the inflammatory pathology of asthma. This study aimed to describe the level of co-expression of the available T2 inflammatory biomarkers used for subtyping of T2 high/low asthma in an unselected patient population and subsequently to describe the association with clinical characteristics and co-morbidities. <b>Methods:</b> The study population consisted of patients from the BREATHE cohort in Denmark and Sweden, 762 with mild-moderate asthma and 97 with severe asthma. T2 markers used were blood eosinophils, FeNO and IgE plus sputum eosinophils. Clinical characteristics, symptoms, quality-of-life and co-morbidities as well as co-expression of T2 markers were described. <b>Results:</b> Patients with mild-moderate asthma were younger (44 vs 48 years), had lower BMI (25.9 vs 27.9), less atopy (53% vs 66%), better lung function (3.2L vs 2.9L) and health status compared to patients with severe asthma, who had a higher symptoms burden (ACQ5: 2.2 vs 1.2; ACT: 20 vs 15) and indications of uncontrolled asthma. Patients with severe asthma showed more pronounced T2 biomarker expression compared to patients with mild-moderate asthma (66% vs 56%); moreover, co-expression of T2 biomarkers was more pronounced in patients with severe vs mild moderate disease (40% vs 28%). Similar rates of ER visits, hospitalizations and OCS use were seen, irrespective of eosinophil count. <b>Conclusion:</b> A majority of patients with asthma expressed at least one T2 biomarker, being more pronounced in severe asthma patients.