Anti-inflammatory treatment of atopic asthma guided by exhaled nitric oxide: A randomized, controlled trial

Background: Atopic asthma is characterized by Th2 cytokine-driven inflammation of the airway mucosa, which is signaled by the fraction of exhaled nitric oxide (F_ENO). Objective: We tested whether an F_ENO-guided anti-inflammatory treatment algorithm could improve asthma-related quality of life and asthma symptom control, and reduce exacerbations in atopic asthmatics within primary care. Methods: Altogether, 187 patients with asthma and who were nonsmokers (age range, 18-64 years) with perennial allergy and who were on regular inhaled corticosteroid treatment were recruited at 17 primary health care centers, randomly assigned to 2 groups and followed up for 1 year. For the controls (n= 88), F_ENO measurement was blinded to both operator and patient, and anti-inflammatory treatment was adjusted according to usual care. In the active group (n= 93), treatment was adjusted according to F_ENO. Questionnaires on asthma-related quality of life (Mini Asthma Quality of Life Questionnaire) and asthma control (Asthma Control Questionnaire) were completed, and asthma events were noted. Results: The Asthma Control Questionnaire score change over 1 year improved significantly more in the F_ENO-guided group (-0.17 [interquartile range {IQR},-0.67 to 0.17] vs 0 [-0.33 to 0.50]; P= .045), whereas the Mini Asthma Quality of Life Questionnaire score did not (0.23 [IQR, 0.07-0.73] vs 0.07 [IQR,-0.20 to 0.80]; P= .197). The change in Asthma Control Questionnaire was clinically important in subpopulations with poor control at baseline (P= .03). Furthermore, the exacerbation rate (exacerbations/patient/y) was reduced by almost 50% in the F_ENO-guided group (0.22 [CI, 0.14-0.34] vs 0.41 [CI, 0.29-0.58]; P= .024). Mean overall inhaled corticosteroid use was similar in both groups (P= .95). Conclusion: Use of F_ENO to guide anti-inflammatory treatment within primary care significantly reduced the exacerbation rate and improved asthma symptom control without increasing overall inhaled corticosteroid use.