Fractional exhaled nitric oxide is associated with more severe asthma

Fractional exhaled nitric oxide (FeNO) levels are used as a marker of airway inflammation. The aim of the present work was to evaluate a possible relationship between FeNO and parameters of asthma control and severity in different asthma phenotypes. FeNO was evaluated in 200 asthma patients (37% male, mean age ± SD 54±15 years, 19% controlled (GINA), 30% treated with oral corticosteroids (OCS), median FEV1 (interquartile range) 2,05 L (1,49-2,70), 74% pred. (56-90%)), together with other asthma characteristics (lung function, asthma control, allergies, serum IgE, serum ECP, and blood eosinophils). Patients with poorly controlled asthma had significantly higher FeNO values (ACQ-5≥1.5 vs. <1.5: FeNO 31 ppb (18-57) vs. 22 ppb (12-40), p=0.016). Similarly, patients with an FEV1 ≤70% pred. had significantly higher FeNO values than patients with an FEV1 >70% (36 ppb (16-62) vs. 24 ppb (13-45), p=0.012). Patients treated with oral corticosteroids as maintenance treatment had significantly higher FeNO values than patients not on OCS (38 ppb (23-60) vs. 24 ppb (13-50), p=0.005). There was no correlation between FeNO levels and IgE, allergies, ECP or eosinophils. In asthma, FeNO concentrations were associated with higher asthma severity as reflected by uncontrolled asthma, lower FEV1 and maintenance treatment with oral corticosteroids.