Type 2 biomarker expression according to age of asthma onset: an analysis of the German severe asthma registry (GAN)

Background: The relevance of the age of asthma onset for type 2 biomarker expression in severe asthma is incompletely understood. Methods: Data of 1512 patients documented in the German severe asthma registry (GAN) were analysed according to age of asthma onset (severe early-onset asthma, SEA: age of onset <18 years of age; severe adult-onset asthma, SAA: age of onset ≥18 years of age). Results: There were 456 patients with SEA (30.2%, median age: 38 years, median age at asthma onset: 5 years) and 1056 patients with SAA (69.8%, median age: 56 years, median age at asthma onset: 40 years). There was no significant difference in the gender distribution (SEA: 59%, SAA: 56.2% females). SAA was characterised by a higher percentage of ever-smokers (SEA: 24.6%, SAA: 48.9%), a higher median BMI (SEA: 24.9 kg/m2, SAA: 26.7 kg/m2), a higher number of very frequent exacerbators (SEA: 4.7%, SAA: 8.3%) and a higher percentage of patients with chronic sinusitis (SEA: 39%, SAA: 56.5%), nasal polyps (SEA: 22.3%, SAA: 45.2%) and Aspirin-exacerbated respiratory disease (SEA: 17.8%, SAA: 23.8%) than SEA. In contrast, there was a lower median FEV1 (SEA: 70%, SAA: 66% predicted), a lower median total serum immunoglobulin E (IgE, SEA: 201 IU/ml, SAA: 169 IU/ml) and a lower prevalence of allergic co-morbidities (SEA: 81.5%, SAA: 57.5%) in SAA than in SEA. Patients with SAA displayed higher median exhaled FeNO values (SEA: 23 ppb, SAA: 41 ppb) and higher median blood eosinophil counts (SEA: 200 cells/µl, SAA: 251 cells/µl) than patients with SEA. Conclusion: Severe adult-onset asthma is characterised by a stronger expression of type 2 biomarkers than severe early-onset asthma.