Severe asthma often co-occurs with chronic rhinosinusitis with nasal polyposis (CRSwNP), marked by increased type 2 inflammation. The similarities in mucosal barrier dysfunction and inflammation have led to the concept of united airways disease through shared presence of type 2 cytokines, local IgE production, and eosinophil infiltration, which make management a challenging task.

We aimed to characterize patients with severe asthma and comorbid CRSwNP in a real-life setting by assessing epidemiology, inflammation, disease control, and lung function parameters.

The German Asthma Net (GAN) is an international, multi-centre, and real-life registry of patients with severe asthma. This cross-sectional study analyzed 1135 patients (39% CRSwNP, 58% female, 53±16 years, 59% frequent exacerbations (?2/year)) through univariate T-tests or Mann-Whitney-U-Tests for continuous, and Chi-Square tests for binary variables.

Patients with severe asthma and comorbid CRSwNP had similar rates of corticosteroid use and yearly exacerbations. However, patients with CRSwNP showed higher levels of exhaled nitric oxide (FeNO) (p<0.001) and blood eosinophil counts (p=0.03), indicating underlying type 2 inflammation. CRSwNP and severe asthma as independent indications for targeted therapies explained the increased use of biologics (60% vs 51%, p=0.003). CRSwNP was more common in adults than in children (p=0.003), and inversely associated with allergic diatheses (spec. IgE, p<0.05).

In conclusion, despite similar rates of corticosteroid use and exacerbations, patients with CRSwNP showed higher levels of FeNO and eosinophils, indicating high type 2 inflammation. Both highly comorbid diseases are independent valid indications for targeted treatments.