Exhaled Nitric Oxide in Allergic Diseases: A Population-Based Study

Abstract

ISEE-727 Objective: The fraction of exhaled nitric oxide (FENO) measurement has attracted increasing interest as a simple, easy, rapid, and noninvasive marker of airway inflammation in asthma. The aim of this study was to determine the relationship between FENO and allergic inflammatory diseases. Materials and Methods: We investigated in 992 subjects living near a large industrial complex in Korea. FENO was measured online in accordance with ATS guideline at a flow rate of 0.05 L/s and 0.1 L/s. The existence of asthma and allergic rhinitis was based upon a history of typical respiratory symptoms and medical examination. Atopy was assessed by skin prick tests to 12 common allergens. Results: FENO increased significantly with age, weight, and height. FENO values were markedly elevated in people with clinically confirmed asthma compared with individuals of no such diagnosis in both flow rates (43.8 vs. 23.6 ppb in 0.05 L/s, P = 0.0015; 23.5 vs. 12.9 ppb in 0.1 L/s, P = 0.0006). FENO levels of those with allergic rhinitis was higher than that of healthy controls (47.9 vs. 20.5 ppb in 0.05 L/s, P<0.0001; 24.9 vs. 11.4 ppb in 0.1 L/s, P<0.0001). There was significant difference in FENO levels between atopic subjects and people who did not react to any allergens (31.1 vs. 20.9 ppb in 0.05 L/s, P<0.0001; 16.6 vs. 11.6 ppb in 0.1 L/s, P<0.0001). FENO levels also strongly correlated with the severity of atopy as determined by the number of positive skin prick reactions [number of SP(+) 0: 20.8, 1: 21.4, 2: 35.1, 3 and more: 36.4 ppb in 0.05 L/s; 11.6, 11.9, 18.5, 19.6 ppb in 0.1 L/s]. Conclusions: In a population, most allergic cases are mild, and the results suggest that FENO is a sensitive marker and a useful parameter for monitoring asthma, allergic rhinitis, and atopy in the community. Its application is a reliable tool of epidemiological surveys on allergies in community.