Role of exhaled nasal nitric oxide in distinguishing between chronic rhinosinusitis with and without nasal polyps.

BACKGROUND: Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP) nasal polyps is a global health concern. Several clinical biomarkers, such as inhaled carbon monoxide and exhaled nitric oxide (NO), have been studied to assess the presence and degree of inflammation in the airway mucosa.

OBJECTIVE: To evaluate the clinical application of exhaled nasal NO (nNO) in distinguishing between CRSwNP and CRSsNP in consideration of the atopic status of patients.

METHODS: Eighty-eight patients with CRS and 20 healthy volunteers were recruited for this study. The exhaled nNO level was measured by using a hand-held device. Nasal endoscopy (with Lund-Mackay scoring of CRS) and sinus computed tomographies (CT) were used to evaluate the nasal cavity and sinuses of the subjects. Atopic status was confirmed by using skin prick tests (SPTs).

RESULTS: The mean ± standard deviation (SD) levels of nNO in patients with CRSsNP were significantly higher than those in patients with CRSwNP (591 ± 153 ppb versus 360 ± 181 ppb, p < 0.001), whereas patients with CRS exhibited lower levels of nNO compared with the control subjects (449 ± 204 ppb versus 881 ± 161 ppb, p < 0.001). Patients with atopy and with and without nasal polyps exhibited significantly higher levels of nNO compared with patients without atopy (atopic CRSsNP versus nonatopic CRSsNP, 734 ± 120 ppb versus 503 ± 92 ppb [p < 0.001]; atopic CRSwNP versus nonatopic CRSwNP, 518 ± 161 ppb versus 299 ± 150 ppb [p < 0.001]). The levels of nNO were negatively correlated with the Lund-Mackay scores in both atopic (r = -0.45; p = 0.016) and nonatopic (r = -0.600; p < 0.001) patients with CRS. Receiver operating characteristic curves differentiated patients as CRSwNP, CRSsNP, and healthy controls, and in atopic and nonatopic subgroups, with acceptable sensitivity and specificity (>70 to 90%).

CONCLUSION: Exhaled nNO levels can be used to distinguish between patients with CRSwNP and patients with CRSsNP. However, the atopic status of the patient influenced the use of nNO as a diagnostic or monitoring biomarker in CRS.