title: Exhaled NO is a poor marker of asthma control in children with a reported use of asthma medication: a pharmacy-based study.
abstract: BACKGROUND
  A high fraction of nitric oxide in exhaled breath (FeNO) has been suggested to be a marker of ongoing airway inflammation and poorly controlled disease in asthma. The usefulness of FeNO to monitor asthma control is still debated today.
  
  
  OBJECTIVE
  To assess the validity of FeNO as a marker of asthma control in children with reported use of asthma medication.
  
  
  METHODS
  Fraction of nitric oxide in exhaled breath was measured in 601 children (aged 4-12 yr) with reported use of asthma medication in the past 6 months and in 63 healthy non-asthmatic children (aged 5-12). Asthma control was assessed by the Asthma Control Questionnaire (ACQ). A receiver-operator characteristics (ROC) curve was generated to assess the accuracy of FeNO as a marker for asthma control. Logistic regression analysis was used to study whether clinical, healthcare, medication, and environmental factors are associated with high FeNO levels (>25 ppb).
  
  
  RESULTS
  Fraction of nitric oxide in exhaled breath had a poor accuracy to discriminate well-controlled from not well-controlled asthma [area under the ROC curve: 0.56 (95% CI: 0.52-0.61, p = 0.008)]. In addition, high FeNO (>25 ppb) was associated with lower medication adherence rates (OR: 0.4; 95% CI 0.3-0.6), fewer antibiotic courses in the past year (OR: 0.6; 95% CI: 0.4-0.9), fewer leukotriene antagonists use in the past year (OR: 0.4; 95% CI: 0.2-0.9), and fewer visits to a (pulmonary) pediatrician (OR: 0.6; 95% CI: 0.4-0.9). Children living in a non-urban environment had more often high FeNO levels (OR: 1.7; 95% CI: 1.1-2.6).
  
  
  CONCLUSIONS
  High FeNO is a poor marker of asthma control in children with reported use of asthma medication. Various other factors, including medication adherence and medication use, are associated with increased FeNO levels.
authors.affiliation: Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
authors.forename: Susanne J H
authors.initials: SJ
authors.lastname: Vijverberg
authors.forename: Ellen S
authors.initials: ES
authors.lastname: Koster
authors.forename: Leo
authors.initials: L
authors.lastname: Koenderman
authors.forename: Hubertus G M
authors.initials: HG
authors.lastname: Arets
authors.forename: Cornelis K
authors.initials: CK
authors.lastname: van der Ent
authors.forename: Dirkje S
authors.initials: DS
authors.lastname: Postma
authors.forename: Gerard H
authors.initials: GH
authors.lastname: Koppelman
authors.forename: Jan A M
authors.initials: JA
authors.lastname: Raaijmakers
authors.forename: Anke-Hilse
authors.initials: AH
authors.lastname: Maitland-van der Zee
mesh_terms: D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy*; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests; D002648:Child; D002675:Child, Preschool; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D010349:Patient Compliance; D010594:Pharmacies / Q000706:statistics & numerical data; D012372:ROC Curve; D011795:Surveys and Questionnaires
chemical_list: D018927:Anti-Asthmatic Agents; D015415:Biomarkers; D009569:Nitric Oxide