The impact of maintenance oral corticosteroids (OCS) on disease burden and type-2 inflammatory signal in the Wessex Severe Asthma Cohort (WSAC)

Introduction: Maintenance OCS use in severe asthma (SA) is associated with significant side-effects and has the potential to mask the systemic type-2 inflammatory biomarker signal required for initiation of biologic therapies. Method: WSAC is a large published cohort of 342 well characterised SA patients fulfilling the ATS/ERS 2014 definition of SA undertaken prior to the widespread use of biologic treatments. We compared the clinical, physiological & biological characteristics of patients requiring & not requiring maintenance OCS. Results: Discussion: Maintenance OCS use is associated with a significantly greater burden of comorbidities, poorer quality of life & disease control with more frequent exacerbations & ITU admissions. Despite this no significant differences were identified in lung function, atopic status, inflammatory cell counts or the other extensive biological measures assessed in the cohort. 44% of patients on maintenance OCS showed no biomarker signal of T2 inflammation. 77% of those on maintenance OCS with a sputum eos ≥2% had a blood eos count ≥0.3x109/L whilst only 60% had a FeNO ≥25ppb (43% FeNO ≥50ppb) suggesting blood eos remains a useful biomarker of T2 inflammation.