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 (ENO), which could not be entirely explained by the association between CRS and asthma. The aim of this study was to investigate the variables associated with increased ENO in patients with CRS.

Methods: This was a prospective cross-sectional descriptive study of 93 consecutive patients with CRS. The effect on ENO of age, gender, atopy, asthma, respiratory symptoms without bronchial hyperresponsiveness (BHR), and nasal polyps was evaluated by multiple regression analysis.

Results: Nasal polyps (P = .01), asthma (P < .001), and respiratory symptoms without BHR (P = .01) were the only independent variables associated with increased ENO. The prevalence of asthma was significantly higher in subjects with nasal polyps (61% vs 29.4%), P = .005, whereas the prevalence of respiratory symptoms without BHR was higher in those without nasal polyps (44.1% vs 15.3%, P = .003). Respiratory symptoms without BHR were associated with significantly higher ENO and prevalence of sputum eosinophilia (eosinophils > 3%) in patients with nasal polyps compared with those without nasal polyps (68.2 vs 24.0 ppb, P = .001; 60% vs 8.3%, P = .03, respectively).

Conclusions: The presence of nasal polyps in patients with CRS was associated with increased asthma prevalence as well as increased ENO levels. Respiratory symptoms without BHR were associated with eosinophilic airway inflammation and increased ENO only in patients with nasal polyps. These findings suggest important clinical and biologic differences between the two types of CRS, with and without nasal polyps.