Abstract
Objective: The Global Initiative for Asthma (GINA) guidelines state that when asthma control is maintained for at least 3 months, treatment can be stepped down; however, prediction tools have not been established for the reappearance of symptoms and increased risk of exacerbation on stepping down treatment. This study was designed to assess whether FeNO measurement predicts asthma exacerbation after stepping down from fixed dose formoterol/budesonide combination (FBC)9/320 μg bid to 4.5/160 μg bid (UMI05406). Methods: Subjects included 37 patients receiving a fixed-dose FBC 9/320 μg bid for at least 3 months, and achieving controlled asthma (GINA) in conjunction with an Asthma Control Questionnaire (5-item version (ACQ5) score ≤ 0.75). Based on the FeNO value at stepping down, patients were classified into 25 patients with FeNO<37 ppb and 12 with FeNO ≥ 37 ppb. The primary endpoint was the occurrence of asthma exacerbation within 8 weeks and from 8 weeks until 12 months. Secondary endpoints, including ACQ5, FeNO, and pulmonary function tests, were measured at baseline and until 8 weeks. Results: There was no difference in the incidence of exacerbation between patients with FeNO ≥ 37 ppb and those with FeNO<37 ppb within 8 weeks; however, in a long-term follow up until 12 months, the incidence was significantly higher in patients with FeNO ≥ 37 ppb than in those with FeNO<37 ppb (odds ratio 11.33, 95% confidence interval 1.45 to 88.52).There was no statistically significant differencein changes in ACQ5, pulmonary functions, and FeNO between the 2 groups by 2-way repeated measures analysis of variance. Conclusions: Higher FeNO levels may predict asthma exacerbation not within a short period of time, but in a long-term follow-up after stepping down FBC therapy in adult asthma.
Highlights
The current asthma guidelines emphasize achieving current control and reducing future risk [1,2]
Previous studies indicated that as a predictor of asthma control, fractional exhaled nitric oxide (FeNO) is no better than more conventional tests and that the predictive values of a single measurement of FeNO for loss of asthma control are insufficiently sensitive and specific [3,4,5]; these studies were concerned with adjusting the inhaled corticosteroid (ICS) dose in controlled but uncontrolled patients while very few have examined the usefulness of FeNO measurement as a predictor of asthma exacerbation in patients with well-controlled asthma receiving an ICS in combination with a long-acting β2-agonist (LABA)
Gelb et al reported that combined baseline FeNO ≥ 28 ppb and FEV1 ≤ 76% of predicted were reliable predictors of exacerbation in patients who were clinically stable for 6 weeks and receiving salmeterol/fluticasone combination (SFC)100/500 μg per day [6]
Summary
The current asthma guidelines emphasize achieving current control and reducing future risk [1,2]. Previous studies indicated that as a predictor of asthma control, FeNO is no better than more conventional tests and that the predictive values of a single measurement of FeNO for loss of asthma control are insufficiently sensitive and specific [3,4,5]; these studies were concerned with adjusting the inhaled corticosteroid (ICS) dose in controlled but uncontrolled patients while very few have examined the usefulness of FeNO measurement as a predictor of asthma exacerbation in patients with well-controlled asthma receiving an ICS in combination with a long-acting β2-agonist (LABA). Hojo et al found that FeNO ≤ 28 ppb plus an Asthma Control Test (ACT) score ≥ 22 for more than 3 months was a safe criterion for stepping down formoterol/budesonide combination (FBC) 18/640 μg per day to 9/320 μg per day without an Received April 01, 2013; Accepted May 15, 2014; Published May 20, 2014
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