Abstract
BackgroundAsthma is a complex syndrome with multiple domains including symptoms, lung function, asthma control, and airway inflammation. A study of Fenom PRO™, a novel monitor for exhaled nitric oxide (FeNO), provided an opportunity to look at concordance/discordance (C/D) for changes in multiple asthma domains over a 2-week period after corticosteroid therapy.MethodsNon-steroid-treated adults and children with uncontrolled asthma had asthma domain measures, (FeNO), forced expired volume in 1 s (FEV1), the 6-item Asthma Control Questionnaire scores (ACQ6), and daily asthma symptoms, assessed before and after a 2-week course of corticosteroids. Asthma symptoms were assessed using a custom novel twice-daily symptom scale (ASX). C/D bidirectional changes in all domains were calculated around both the zero point, and around the minimal important difference (MID) in relevant subjects.ResultsThere was a highly significant fall in mean FeNO of 51.7% over 2 weeks (p < 0.0001) accompanied by significant improvements in mean FEV1, ACQ6 and ASX scores. However, C/D between individual domains varied considerably between subjects. The C/D between parameters for any change around zero for the combined adults and pediatric population was best for FeNO and ACQ6, 79.3/20.7% while FEV1 was more discordant than other parameters in general. When considering changes around the minimal important difference (MID) in a subset, the level of concordance increased in general, with FeNO and ACQ6 demonstrating a C/D of 93.5/6.6%.ConclusionThis data demonstrates that the concordance between changes in the asthma domains is often substantially less than 100%. Reasons for this may include different time courses for change of the separate domains, the degree of abnormality for each domain at baseline, as well as intrinsic limitations of each parameter.
Highlights
Asthma is a complex syndrome with multiple domains including symptoms, lung function, asthma control, and airway inflammation
This study provided an opportunity to evaluate short-term concordance/discordance (C/ D) between asthma domains, namely day and nighttime symptoms, forced expired volume in 1 s (FEV1), asthma control via the 6-item ACQ6, and airway inflammation using FeNO which is the focus of this report
Based on US regulatory requirements to register a novel device, the primary objective was to demonstrate that a novel FeNO monitor, Fenom PROTM (Spirosure, Pleasanton, CA, USA), can detect a significant change in FeNO, a marker of airway inflammation following short-term corticosteroid therapy prescribed for uncontrolled asthma
Summary
Asthma is a complex syndrome with multiple domains including symptoms, lung function, asthma control, and airway inflammation. A study of Fenom PROTM, a novel monitor for exhaled nitric oxide (FeNO), provided an opportunity to look at concordance/discordance (C/D) for changes in multiple asthma domains over a 2-week period after corticosteroid therapy. Asthma is a complex syndrome characterized by episodic and chronic symptoms e.g. wheezing, cough, chest tightness and dyspnea, as well as periodic exacerbations which may require short courses of corticosteroids. A recent study was performed to fufill US regulatory requirements [1] for clearing a novel FeNO monitor Fenom ProTM. This study provided an opportunity to evaluate short-term concordance/discordance (C/ D) between asthma domains, namely day and nighttime symptoms, FEV1, asthma control via the 6-item ACQ6, and airway inflammation using FeNO which is the focus of this report
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