Characteristics of severe asthma patients with biologic treatment in the Swedish National Airway Register

The Swedish National Airway Register (SNAR) includes data on asthma control, lung function, biomarkers, treatments, and comorbidities from asthma patients in primary and secondary care. This study aimed to describe patients with severe asthma receiving biologic treatment in SNAR and to explore its potential as a national registry for severe asthma.

Patients with ongoing treatment with mepolizumab, benralizumab, reslizumab, dupilumab or tezepelumab and registered in SNAR between 2016 and 2024 were included. Demographic characteristics, asthma treatment, asthma control, lung function, type 2 biomarkers, and exacerbation history were described. Data were assessed at inclusion and at the most recent follow-up available.

A total of 416 patients were identified; 49% were female, mean age was 54.1 years, and mean BMI was 27.2. Inhaled corticosteroids were used by 94.4% of patients, while 39.2% received maintenance oral corticosteroids at inclusion. Asthma control was generally low and exacerbations were common. Patients differed across biologic classes with respect to age, comorbidities, lung function and biomarker profiles, reflecting heterogeneity. At follow-up (mean 193 days), improvements were observed in asthma control, lung function, type 2 biomarkers, and exacerbation frequency. Marked geographic variation in registry inclusion was identified, with several regions reporting no patients.

SNAR enables nationwide characterization of patients with severe asthma treated with biologics in routine care. However, variation in inclusion and follow-up limits longitudinal interpretation. More standardized registration, particularly at treatment initiation, would strengthen SNAR's role in national monitoring, quality improvement and future research.