Interrelationships among asthma, atopy, rhinitis and exhaled nitric oxide in a population-based sample of children

Abstract

Background: Exhaled nitric oxide (eNO) has attracted increasing interest as a non-invasive marker of airway inflammation in asthma. However, little evidence exists on the influences exerted on eNO by the interrelations among atopic status, asthma and rhinitis. Methods: Among the 1156 children who participated in a large-scale epidemiological survey on asthma and allergies (ISAAC II: International Study of Asthma and Allergies in Childhood Phase II) in the city of Clermont-Ferrand, 53 asthmatics without corticosteroid treatment and 96 non-asthmatics were invited to perform eNO and skin prick tests (SPTs) to 12 common allergens. Results: Atopic asthmatic children had higher eNO than non-atopic asthmatic children (28.9 ± 9.1 vs. 17.1 ± 13.1 p.p.b.; P = 0.0004) with a significant increase when one SPT or more are positive (26.5 ± 7.8 vs. 17.1 ± 13.1 p.p.b.; P = 0.03). Similarly, non-asthmatic, atopic subjects had higher eNO than non-atopic subjects with a significant increase when two SPTs or more are positive (19.4 ± 9.8 vs. 11.7 ± 6.7 p.p.b.; P = 0.003). In the case of equal levels of positive SPTs (0, 1, ≥2), asthmatic children always had higher eNO than non-asthmatic ones. Furthermore, among non-asthmatic children, the eNO level increased only in atopics who had rhinitis (20.7 ± 13 vs. 12.5 ± 6.4 p.p.b. in atopic controls (subjects without rhinitis and asthma) and 12.3 ± 6.6 p.p.b. in non-atopic controls; P = 0.001), whereas among asthmatic children, eNO level increased in atopics independently of rhinitis (28.2 ± 9.5 p.p.b. in those with rhinitis and 30.9 ± 8.1 p.p.b. in those without) as well as in non-atopics with rhinitis (22.5 ± 17.2 p.p.b.). Conclusions: Our data suggest that besides atopy and asthma, allergic rhinitis should also be taken into account in the assessment of eNO.