Association between exhaled nitric oxide and nasal polyposis in severe asthma.

Background: Although several contributions exist on the role of fractional exhaled NO (FeNO) in diagnosis and management of asthma, no studies have analysed the association between FeNO in patients with severe asthma and nasal polyposis.

Aim: We investigated the potential association between FeNO and the presence of nasal polyps in patients affected by severe asthma.

Methods: Study population included 93 severe asthmatic adult patients consecutively enrolled from four Italian specialist clinic centres from 2015 to 2018. In these patients lung function, asthma control, FeNO, blood eosinophils and CT scan of paranasal sinuses were evaluated.

Results: Nasal polyposis was observed in 28 patients (30%). Among univariate predictors (lower BMI, higher FeNO, eosinophil and neutrophil count), recursive partitioning analysis identified as best predictors of nasal polyposis high values of eosinophil count (≥6.5% or >420 cells/mm) and FeNO (≥39 ppb). The 40 patients with low eosinophil count and FeNO had a significant lower occurrence of nasal polyposis than those with higher values (8% vs 58%; p < 0.001). The stratification algorithm had a good performance in discriminate patients with and without nasal polyposis (area under the receiver operating characteristic curve of 0.768).

Conclusions: Our results show that FeNO might improve to detect nasal polyposis in patients with severe asthma and a low level of blood eosinophils counts, identifying individuals with high susceptibility to this condition.