Impact of exhaled nitric oxide measurements on treatment decisions in an asthma specialty clinic.

Background: Asthma management in an outpatient setting is best accomplished by clinical evaluation coupled with spirometry and symptom evaluation, but these assessments do not provide information about airway inflammation. Exhaled nitric oxide (fraction of exhaled nitric oxide [FeNO]) measures T-helper cell type 2-mediated airway inflammation and may be a useful adjunct in asthma management.

Objective: To determine whether the use of FeNO in the specialist management of asthma results in more effective and cost-effective treatment decisions.

Methods: Fifty subjects 7 to 60 years old with established asthma participated in this observational study. Subjects were evaluated by clinical examination, spirometry, and symptom assessment using the Asthma Control Test, and clinicians estimated airway inflammation and made treatment decisions based on these assessments. Then, FeNO was measured, and changes in therapy based on FeNO levels were documented. The estimated cost impact of using FeNO was calculated presuming ongoing FeNO use in patient management.

Results: Without FeNO, the clinician's assessment of airway inflammation was incorrectly classified in 50% of subjects. FeNO results substantially altered treatment decisions in more than one third of subjects, notably medication augmentation in 10 (20%) and medication decreases in 8 (16%). Use of FeNO in addition to standard of care was estimated to save $629 per subject per year.

Conclusion: Measurement of FeNO augments routine clinical assessment of asthma by measuring airway inflammation. Knowledge of FeNO affects medication treatment decisions to augment or decrease pharmacotherapy, which has important long-term asthma management implications, most notably the potential to lower the costs and morbidity associated with asthma exacerbation.

Trial Registration: ClinicalTrials.gov identifier NCT01729247.