BACKGROUND: We have reported that increased fraction of exhaled nitric oxide (FeNO), a measure of TH2 -driven airway inflammation, and blood eosinophil count, a marker of systemic eosinophil inflammation, correlated with asthma attacks in a population-based study.
OBJECTIVE: To investigate the relation between simultaneously elevated FeNO and serum eosinophil cationic protein (S-ECP) levels and asthma events among asthmatics.
METHODS: Measurements of FeNO (elevated ≥ 25 ppb) and S-ECP (elevated ≥ 20 ng/mL) were done in 339 adult asthmatics. Asthma events (attacks and symptoms) were self-reported.
RESULTS: Simultaneously normal S-ECP and FeNO levels were found in 48% of the subjects. Subjects with simultaneously elevated S-ECP and FeNO (13% of the population) had a higher prevalence of asthma attacks in the preceding 3 months than subjects with normal S-ECP and FeNO (51% vs. 25%, p = 0.001). This was not found for subjects with singly elevated S-ECP (p = 0.14) or FeNO (p = 0.34) levels. Elevated S-ECP and FeNO levels was independently associated to asthma attacks in the preceding 3 months after adjusting for potential confounders (OR (95% CI) 4.2 (2.0-8.8).
CONCLUSIONS: Simultaneous elevated FeNO and S-ECP related to a higher likelihood of asthma attacks in the preceding 3 months. This indicates that there is a value in measuring both FeNO and systemic eosinophilic inflammation in patients with asthma in order to identify individuals at high risk of exacerbations. This article is protected by copyright. All rights reserved.