Detailed physiological profiling of patients for a study investigating the airway microbiome

Introduction: Evidence-based patient stratification is required to address the hetergeneity of asthma severity. Detailed physiological profiling of symptomatic patients is important and of increasing interest in airway microbiome studies. Aims and objectives: Detailed high quality physiological parameters were recorded from lung function tests in subjects included in an airway microbiome study. Subjects underwent testing in order to build individual physiological profiles and categorise the subjects into control, asthma and airway hyperresponsive groups. Methods: 48 adult subjects (17 controls, 31 patients) performed spirometry, lung volumes and diffusing capacity tests. Asthma was confirmed by significant bronchodilator response (BDR). Airway Hyperresponsiveness (AHR) was confirmed by a positive methacholine challenge test. Profiling also included end tidal carbon dioxide (etCO2), fraction of exhaled Nitric Oxide (FeNO) and skin prick allergy tests. Results: Prelimary data shows that patients were classified as asthma (15) or AHR (16). AHR was categorised into borderline (6), mild (5), moderate (5) subgroups. Significant difference in atopy status was observed in controls versus asthma/AHR groups (31.3% vs 87.5%). Largest incidence of atopy was observed in the mild and moderate hyperresponsive subgroups (100%). No significant gender differences in atopy were observed. FeNO was significantly elevated in the asthma group and the moderate AHR subgroups compared to controls (p=0.03) Conclusions: Using detailed classification there was significant separation between controls and sub categories of asthma and airway hyperresponsiveness profiles.