Diagnostic Value and Clinical Application of Nasal Fractional Exhaled Nitric Oxide in Subjects with Allergic Rhinitis.

PURPOSE: Nitric oxide (NO) is a potential marker in the diagnosis and monitoring of treatment for the management of patients with allergic rhinitis (AR). The study aimed to determine the value of nasal fractional exhaled nitric oxide (FeNO) in the diagnosis and treatment response of AR patients. METHODS: The participants were divided into control and allergic rhinitis groups based on the clinical symptoms and skin prick tests. The AR group was treated with intranasal corticosteroid after the diagnosis. The nasal fractional exhaled nitric oxide (FENO) levels were compared between control and AR groups. In the AR group, the visual analogue scale (VAS), Nasal Obstruction Symptoms Evaluation (NOSE) questionnaire, and nasal fractional exhaled nitric oxide (FeNO) were assessed pre- and post-treatment. RESULTS: One hundred ten adults were enrolled. The nasal FeNO level was significantly higher in AR compared to control (p < 0.001). Both the subjective (VAS and NOSE), both (p < 0.01) and objective (nasal FeNO, p < 0.001) assessments showed significant different pre- and post-treatment. The threshold level of nasal FeNO in the diagnosis of AR was 390.0 ppb (sensitivity of 73% and specificity of 80%) based on the receiver operator characteristic curve. CONCLUSION: Nasal FeNO level is significantly higher in AR compared to control group with significant difference pre- and post-treatment. The findings suggest nasal FeNO can serve as an adjunct diagnostic tool together with the monitoring of treatment response in AR.