Clinical and Economic Burden of Severe Asthma With Low Blood Eosinophil Counts

Abstract

BackgroundType 2 (T2) low severe asthma phenotype is often a result of corticosteroid-overtreated T2-disease due to persistent symptoms, often not related to asthma, and unlikely to respond to high-dose corticosteroid treatment. ObjectiveThis study aimed to characterise severe asthma patients with low eosinophil counts (<300 cells/μl) and describe their disease burden and treatment across healthcare settings in the UK. MethodsA retrospective cohort study of severe asthma patients using linked Clinical Practice Research Datalink (CPRD) Aurum-Hospital Episode Statistics (HES) and UK Severe Asthma Registry (UKSAR) data indexed patients on latest blood eosinophil count (BEC). Clinical characteristics, treatment patterns, outcomes, and healthcare resource use (HCRU) were described by baseline BEC (≤150 and >150 to <300 cells/μl). ResultsAnalysis included 701 (CPRD-HES) and 1,546 (UKSAR) patients; with 60.5% and 59.4% having BECs ≤150 cells/μl at baseline, respectively. Across BEC groups, the proportion with uncontrolled asthma (≥2 exacerbations) at follow-up (12-months post-index) was 5.4% in CPRD-HES and 45.2% in UKSAR. Maintenance OCS use remained high across BEC groups (CPRD-HES: 29.4%; UKSAR: 51.7%), symptom control remained poor (>200 μg SABA or >500 μg terbutaline/day in CPRD-HES: 48.8%; median ACQ-6 score in UKSAR: 2.0 [1.0-3.3]). HCRU were similar across BEC groups. ConclusionMost patients managed in primary care were infrequent exacerbators, whilst UKSAR patients exacerbated frequently. Large proportions of both patient groups had poor symptom control and continued to receive high levels of maintenance OCS, increasing risk of corticosteroid-induced morbidity. These data highlight the need for rigorous assessment of underlying disease pathology to guide appropriate treatment.