Determinants of exhaled nitric oxide in chronic rhinosinusitis

BACKGROUND: Chronic rhinosinusitis (CRS) has been reported to be associated with increased values of exhaled nitric oxide (Fe(NO)), which could not be entirely explained by the association between CRS and asthma. The aim ot the study was to investigate the variables associated with increased Fe(NO) in patients with CRS. METHODS: Prospective cross sectional descriptive study of 93 consecutive patients with CRS. The effect on Fe(NO) of age, gender, atopy, asthma, respiratory symptoms without bronchial hyperresponsiveness (BHR), and nasal polyps was evaluated by multiple regression analysis. RESULTS: Nasal polyps (p=0.01), asthma (p<0.001) and asthma respiratory symptoms without BHR (p=0.01) were the only independent variables associated with increased Fe(NO). The prevalence of asthma was significantly higher in subjects with nasal polyps (61% vs 29.4%), p=0.005, while the prevalence of respiratory symptoms without BHR was higher in those without nasal polyps (44.1% vs 15.3%, p=0.003). Respiratory symptoms without BHR was associated with significantly higher Fe(NO) and prevalence of sputum eosinophilia (eosinophils > 3%) in patients with nasal polyps compared to those without nasal polyps (68.2 ppb vs 24.0 ppb, p=0.001; 60 vs 8.3 %, p= 0.03, respectively). CONCLUSIONS: The presence of nasal polyps in patients with chronic rhinosinusitis was associated with increased asthma prevalence as well as raised Fe(NO) levels. Respiratory symptoms without BHR were associated with eosinophilic airway inflammation and increased Fe(NO) only in patients with nasal polyps. These findings suggest important clinical and biological differences between the two types of CRS, with and without nasal polyps.