Characterisation and Cluster Analysis of Adult Indian Asthmatics in Vellore District

Background<br/>There is a huge burden of asthma in India, with an estimated 34.3 million patients comprising 13% of the global burden. Little is known about asthma phenotypes, endotypes and clusters amongst native Indian patients.<br/>Objective<br/>To describe asthma phenotypes and clusters in a specialist outpatient service, Vellore, India.<br/>Methods<br/>Systematic assessment was conducted as per GINA 2021 guidelines. Data on demographics, types of indoor pollution exposure, comorbidities, skin tests to aeroallergens (dust mite, pollens, cockroach, cat, dog, aspergillus and alternaria), spirometry, FeNO, blood eosinophils, total IgE, %sputum eosinophils and %sputum neutrophils were captured prospectively. Descriptive statistics were generated, and latent cluster analysis undertaken.<br/>Results<br/>N= 125; M=58 (47.6±15yrs; F=67 (42.8±11yrs) asthmatics were included, and 3 overlapping clusters identified. <br/>Cluster-1: Highest sensitisation to aeroallergens, lowest sputum %neutrophil &amp; %eosinophil and moderate-severe asthma. <br/>Cluster-2: Moderate rate of dust mite and modest rate of other aeroallergen sensitisation, mixed eosinophilic and neutrophilic airway inflammation, moderate-severe asthma and lowest predicted FEV1. <br/>Cluster-3: Modest/moderate rate of sensitisation to aeroallergens, highest sputum %eosinophils and mild-moderate asthma. <br/>Demographic variables, BMI, age of onset, serum total IgE, blood eosinophils, FeNO, and comorbidities were comparable between clusters. A weak but significant positive correlation (r=0.20; p&lt;0.05) was detected between sputum and blood eosinophils, and there was no correlation between sputum eosinophils and FeNO.<br/>Conclusion<br/>There are overlapping asthma clusters in Vellore district based on clinical and physiological variables and biomarkers in peripheral blood and sputum. Large multicentre studies are needed to characterise asthma in India and shape national guidelines.<br/>Clinical Implications: Description of asthma clusters amongst Indian patients in resource-limited settings employing relatively simple clinical and physiological variables and biomarkers in sputum and blood may shape the development of national guidelines for asthma management.<br/><br/>