Exhaled NO is a poor marker of asthma control in children with a reported use of asthma medication: a pharmacy-based study

To cite this article: Vijverberg SJH, Koster ES, Koenderman L, Arets HGM, van der Ent CK, Postma DS, Koppelman GH, Raaijmakers JAM, Maitland‐van der Zee A‐H. Exhaled NO is a poor marker of asthma control in children with a reported use of asthma medication: a pharmacy‐based study. Pediatr Allergy Immunol 2012: 23: 529–536. 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. Aim: 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). Conclusion: 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.