Nasal nitric oxide in objective evaluation of chronic rhinosinusitis therapy

Background: The assessment of the response of chronic rhinosinusitis (CRS) to therapy is difficult. Computerized tomographic (CT) scans cannot be repeatedly used so measures such as symptom scores, endoscopic findings, and parallel measures such as saccharin clearance time are employed instead. Objective: To study the effect of CRS therapy on nasal nitric oxide and to see whether nasal nitric oxide level changes correlate with other assessments. Methods: The study was a prospective randomized trial of patients with CRS, with or without polyps, who had failed initial medical therapy with douching and nasal corticosteroids and who then had abnormal CT scans. They were treated either medically or surgically, with follow up at 6 and 12 months whilst still taking nasal corticosteroids. Nasal nitric oxide was measured initially and at 6 and 12 months as well as symptom scores, endoscopy, polyp grading, and saccharin clearance time. Results: Initial absolute nasal nitric oxide levels correlated inversely with CT scan changes, (P < 0.001). The percentage rise in nasal nitric oxide seen on both medical and surgical treatment correlated with changes in symptom scores (P < 0.001), saccharin clearance time (P < 0.001), endoscopic changes (P < 0.001), polyp grades (P < 0.05 at 6 months, P < 0.01 at 12 months) and surgical scores (P < 0.01). There was no significant correlation with age, sex, smoking or allergy. Conclusion: Nasal nitric oxide, which is easily measured, provides a valuable non-invasive objective measure of the response of CRS to therapy. Topical nasal corticosteroids may be needed to reduce the contribution of nasal epithelial nitric oxide and allow that emanating from the sinuses to be measured.