Relationship between Exhaled Nitric Oxide and Levels of Asthma Control in Asthma Patients Treated with Inhaled Corticosteroid

Utility of exhaled nitric oxide to guide mild asthma treatment in atopic patients and its correlation with asthma control test score: a randomized controlled trial

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is used for the diagnosis and monitoring of asthma, although its utility to guide treatment and its correlation with other tools is still under discussion. We study the possibility to withdraw inhaled corticosteroid treatment in atopic patients with mild asthma based on the FeNO level, as well as to study its correlation with other clinical control tools.

METHODS

Prospective and randomized study including atopic patients aged 18 to 65 with mild asthma, stable, on low-dose inhaled corticosteroid (ICS) treatment, who had their treatment withdrawn based on a FeNO level of 40 ppb. Patients were randomized into two groups: control group (treatment with ICS was withdrawn regardless of FeNO level) and experimental group (according to the FeNO levels, patients were assigned to one of two groups: FeNO > 40 ppb on treatment with budesonide 200 mcg every 12 h and SABA on demand; FeNO ≤ 40 ppb only with SABA on demand). Follow-up was conducted for one year, during which medical assessment was performed with FeNO measurements, asthma control test (ACT), lung function tests (FEV1, FEV1/FVC, PEF, and RV/TLC), and recording of the number of exacerbations.

RESULTS

Ninety-two patients were included, with a mean age of 39.92 years (SD 13.99); 46 patients were assigned to the control group, and 46 patients to the experimental group. The number of exacerbations was similar between the groups (p = 0.301), while the time to the first exacerbation was significantly shorter in the control group (30.86 vs. 99.00 days), p < 0.001, 95% CI (43.332-92.954). Lung function tests (FEV1, FEV1/FVC, PEF, and RV/TLC) showed no differences between the groups (p > 0.05). Both FeNO and ACT showed significant changes in the groups in which ICS was withdrawn (p < 0.05 for both parameters). A significant negative correlation was observed between FeNO and ACT (r = -0.139, p = 0.008).

CONCLUSIONS

In atopic patients with mild asthma, withdrawal of ICS based on an FeNO of 40 ppb led to worsened symptoms but without changes in lung function tests or an increase in exacerbations. There was a negative correlation between FeNO values and symptomatic control measured by the ACT.

TRIAL REGISTRATION

Clinical Trial Number: 2012-000372-42. Start Date: 2012-07-23. Trial registered prospectively ( https://www.clinicaltrialsregister.eu/ctr-search/search?query=2012-000372-42 ). This study adheres to CONSORT guidelines of randomised control trials.

Clinical application of exhaled nitric oxide measurements in a korean population

Nitric oxide (NO) is a biologic mediator of various physiologic functions. Recent evidence suggests the clinical utility of fractional exhaled NO (FeNO) as a biomarker for assessing asthma and other respiratory diseases. FeNO methodologies have been recently standardized by international research groups and subsequently validated in several Korean population studies. Normal ranges for FeNO have been reported for various ethnic groups, and the clinical utility has been widely evaluated in asthma and various respiratory diseases. Based on current evidence including most of Korean population data, this position paper aims to introduce the methodological considerations, and provide the guidance for the proper clinical application of FeNO measurements in Korean populations.