Burden of low-eosinophil severe asthma in the UK

Published online July 18, 2024

Severe asthma is characterized by frequent disease exacerbations and high symptom burden and is estimated to affect up to 5% of asthma patients. The substantial majority of patients with severe asthma have disease that is driven by type 2 (T2) inflammation; however, a small group of patients have persistently poor disease control despite low levels of T2 inflammation, which is often due to overtreatment with corticosteroids. Many treatments available in severe asthma are aimed at T2 inflammation and are not effective in low-eosinophil patients; however, little is known about the disease burden of these patients.

In a study by Busby et al., published in a recent issue of the The Journal of Allergy and Clinical Immunology: In Practice, the authors characterized 701 patients with low-eosinophil severe asthma (blood eosinophils <150 cells/µL) treated in primary care and 1,546 patients treated in specialist care in the UK. Data for patients treated in primary care were from the Clinical Practice Research Datalink database, and data for specialist care were from the UK Severe Asthma Registry. Medication use and disease control were assessed during a 12-month baseline period before the patient’s latest blood eosinophil measurement and during a 12-month follow-up period.

At baseline, patients treated in primary care had low levels of exacerbation, whilst patients in specialist care had high exacerbation levels and poor symptom control. At follow-up, patients in primary care continued to have low exacerbation levels, but despite this, use of reliever medication remained high, indicating poor disease control. Patients treated in specialist asthma care saw reduced corticosteroid use and better disease control following treatment, which in most cases was with biologic drugs targeting T2 inflammation. However, in many cases these patients had significant ongoing corticosteroid use and poor disease control. In summary, it is important that treating physicians review the clinical characteristics and treatment of their low-eosinophil severe asthma patients and consider reducing corticosteroid doses in the first instance or referring patients to specialist care if exacerbation rate is high.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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