Airway dysfunction in nasal polyposis: a spectrum of asthmatic disease?

Background Chronic rhinosinusitis with nasal polyposis (CRSwNP) represents an interesting model to investigate the existence of a non-allergic unified airway. The factors associated with airway dysfunction in CRSwNP are not fully understood.

Objective To assess the impact of nasal disease on lower airway dysfunction in CRSwNP.

Methods Fifty-seven patients with CRSwNP underwent spirometry, nasal endoscopy, exhaled nitric oxide, methacholine bronchial challenge, blood sampling for total IgE, eosinophil count and radioallergosorbent testing (NCT00788749). Three phenotypic groups were identified: 'asthma group' (asthma diagnosis); 'inflammatory group' [no asthma diagnosis, but elevated fractionated exhaled nitric oxide (FENO) and/or bronchial-hyperreactivity (BHR)]; and 'non-inflammatory group' (no asthma diagnosis, no BHR and normal FENO). Group comparisons, univariate and multivariate analyses were performed to examine associations with airway dysfunction.

Results FEV1 and FEF25-75% were reduced in asthma, but there was no difference between the non-asthmatic groups. Total IgE and eosinophils were elevated in asthma vs. the noninflammatory group, but there was no difference for asthma vs. inflammatory groups. BHR was the only significant predictor of FEV1 (P<0.001). For FEF25-75, BHR and eosinophil count were independent predictors (P<0.001 and P = 0.04). Nasal outcomes were not predictors of spirometry.

Conclusion and Clinical Relevance In CRSwNP there is asymptomatic airway dysfunction suggestive of an asthmatic phenotype. Impairment of lung function is significantly associated with BHR and eosinophilia but not parameters of nasal disease suggesting that severity of airway dysfunction relates to the spectrum of asthma rather than rhinosinusitis. Lower airway dysfunction is common in CRSwNP but does not correlate to the severity of nasal disease. Signs and symptoms of asthma should be sought and treated in CRSwNP.