P16\u2005Can FeNO be used to optimise management of asthma?

Abstract

Introduction and objective Fractional exhaled nitric oxide (FeNO) is a breath biomarker believed to measure type 2 inflammation, which drives the pathogenesis of some types of asthma. FeNO has recently been implemented in asthma diagnostic algorithms.1 However, there is ongoing debate around whether FeNO is useful in managing asthma long-term and in guiding treatment decisions.FeNO has been proposed in a precision medicine approach to asthma management, however more research is required to be able to target the group of patients in which it is a potentially useful biomarker. The purpose of this study was to (1) assess the performance of FeNO as a biomarker of airway inflammation in relation to ACT (asthma control test) (2) distinguish patients in whom FeNO can be relied upon to guide asthma management from those in whom follow up FeNO values have limited clinical significance. Methods A 3-year retrospective study was carried out involving 171 asthmatic adults attending asthma clinic at Wythenshawe Hospital (University of Manchester NHS Foundation Trust). Subjects were stratified into 4 groups based on ACT score and FeNO level. The demographics of each group were compared. Statistics Data was compared between groups using either Kruskal-Wallis or Chi Square. Mann-Whitney U test was used to determine how each group differed from one another; results were considered significant if p<0.05. Results 46.2% of all asthma patients were concordant for FeNO and asthma severity (ACT); Of these 19.7% had high FeNO (>25ppb) with poor asthma control (ACT <20) and 26.5% had low FeNO (<25ppb) and good asthma control (ACT >20). 53.8% demonstrated non-concordance (FeNO and ACT did not correlate). Within the FeNO/ACT concordant groups there were significantly more females and non-smokers (p<0.05 for both). Moreover, an inverse relationship was noted between change in FeNO against (1) change in ACT score and (2) change in steroids against change in FeNO (p<0.05). Conclusion Although change in FeNO has emerged as a potential marker in asthma treatment, further studies are needed to understand the efficacy especially in the disconcordant groups. Reference Overview | Asthma: diagnosis, monitoring and chronic asthma management | Guidance | NICE.Abstract P16 Table 1 shows the demographical differences between the different groups of patients Discordant Concordant Characteristics DHF DLF CHF CLF Number 29 34 23 32 FeNO 42 (27) 11(11) 42 (30) 11(6) ACT 21(3) 15(7) 17(7) 22(2) Age (years)* 48 (40) 46 (29) 26 (23) 44 (25) BMI (kg/m2) 25 (5.9) 32.7 (13.9) 23.8 (5.7) 34.4 (16) Male: Female * 1: 1 1: 1 1:3 1:3 Percentage smoker* 82 60 19 42 Total IgE (KU/L) 350 (550) 185 (455) 247 (745) 199 (353) Highest Blood eosinophils count(10^9L ) * 0.6 (0.8) 0.2 (0.3) 0.6 (0.6) 0.3 (0.3) Percentage with blood eosinophils count≥(0.48*10^9L ) * 51.7 17.6 56.5 21.9 Steroid level (mcg/ BDP) 800 (910) 800 (920) 760 (400) 800 (600) pulmonary function test (FEV1: FVC) 0.70 (0.3) 0.76 (0.11) 0.81(0.14) 0.76 (0.17) Key: 1.DHF - Dis concordant high FeNO 2.DLF - Dis concordant Low FeNO 3.CHF - Concordant High FeNO 4.CLF- Concordant low FeNO Data are represented as median (IQR) *denotes the characteristics in which difference was statistically significant between the groups with p<0.05 using Kruskal Wallis Test or chi square test for categorical variable. Bold characters are used to show data which are significantly different from the other groups in the same category with P<0.05 using Mann-Whitney test.