The association between chronic rhinosinusitis, bronchiectasis and type 2 inflammation: an EMBARC registry analysis

Introduction: Chronic rhinosinusitis (CRS) is a common comorbidity in bronchiectasis. Previous studies suggested that bronchiectasis with CRS is associated with elevated type 2 biomarkers, representing an "eosinophilic bronchiectasis" phenotype. However, whether the association with type 2 inflammation exists in rare aetiologies of bronchiectasis such as primary ciliary dyskinesia (PCD) or immune deficiency is unknown. Our aim was to explore the prevalence of CRS with and without nasal polyposis (CRSwNP and CRSnNP), their impact on bronchiectasis outcomes, and their association with type 2 inflammatory biomarkers in patients with bronchiectasis of various aetiologies. Methods: Using data from the EMBARC bronchiectasis registry, we classified patients with bronchiectasis as having no CRS, CRSnNP or CRSwNP. Regression models were used to test the effect of CRS on symptom scores and long-term outcomes. Multivariate models were created for elevated "type 2 biomarkers", defined as elevated blood eosinophil count or total IgE. Results: Among 16 640 people with bronchiectasis, 2703 (20.9%) had CRSnNP and 1223 (7.3%) had CRSwNP. CRSwNP and CRSnNP were associated with worse symptoms and more frequent exacerbations, but lower hospitalisations and mortality. Type 2 biomarkers were elevated in people with comorbid CRSwNP in idiopathic bronchiectasis, but not in bronchiectasis secondary to PCD or immune deficiency. In multivariable analysis, CRSwNP was independently associated with elevated type 2 biomarkers. Conclusions: CRS and nasal polyposis are common comorbidities in bronchiectasis, associated with worse symptoms and exacerbations. Elevated type 2 biomarkers are associated with CRS, but this finding is dependent on the aetiology of bronchiectasis.