Relation of asthma control and exhaled nitric oxide in patients with bronchial hyperresponsiveness to methacholine

Introduction: Questionnaires used to assess control of asthma are simple and pratical instruments to use in clinical practice, however its relation with airway inflammation remains unclear. Objective: To evaluate the relation between asthma control, spirometry results and measurement of exhaled nitric oxide (FeNO) in patients with asthma and bronchial hyperresponsiveness to methacholine. Methods: Cross-sectional study of patients with suspicion of asthma that, in a 1 year period, went to a pulmonary function test laboratory perform methacholine challenge. Selection of patients with positive methacholine challenge and application of the questionnaires CARAT ("Control of Allergic Rhinitis and Asthma Test") and ACT ("Asthma Control Test"), measurement of FeNO and spirometric parameters. Results: Of the 123 patients who underwent methacholine challenge, 41 (33,3%) were positive. Of these, 68,3% were female, with a mean age of 31,5 years, 73,2% non smokers, 53,7% with atopy, 63,4% with rhinitis, 31,7% in regular treatment with inhaled corticosteroids. The average score of CARAT was 19,3 and ACT 20,5. The average value of FeNO was 43,9 ppb. There was no significant association between scores of total CARAT and ACT with FeNO value or FEV1. The score between total CARAT and ACT had a significant relation (p <0,001, r=0,789). Patients with atopy had higher mean values of FeNO (56,9 vs 26,4, p=0,023). Conclusion: In this sample, there was no significant association between asthma control and FeNO in patients with bronchial hyperresponsiveness to methacholine. There was good relation between the two questionnaires. The presence of atopy was associated with higher FeNO values.