Utility of point-of-care Blood Eosinophils and Exhaled Nitric Oxide as biomarkers in predicting childhood asthma attacks: a pragmatic real-world observational study (BEENO)

Research question: Can blood eosinophils, measured using a finger prick point-of-care test, and/or exhaled nitric oxide (FeNO) be used to predict the risk of an asthma attack in school-aged children? Background: Asthma affects 10% of UK children. Asthma attacks are among the most common reason for hospital admission in children, and the UK has among the highest rates of childhood deaths associated with severe asthma attacks in Europe. Although children are routinely reviewed to assess their asthma control, currently, the only reliable marker of predicting the risk of an asthma attack is having had a previous attack. It is not possible to say how soon a child may have an attack, and we cannot predict risk for the individual child. Objective tests that measure airway inflammation, such as FeNO (a breath test) and blood eosinophils, have been used to develop a predictive risk score in adults, but the predictive utility of these tests in children is unknown. FeNO is routinely measured in specialist paediatric asthma clinics, however venepuncture for blood eosinophils, with results not being available for several hours prevents their use. We have shown finger prick capillary blood samples can be used with a validated point-of-care (POC) test for blood eosinophils successfully in children. Aims and Objectives:To assess the feasibility and acceptability of doing POC blood eosinophils alongside FeNO, symptom score and spirometry in asthma clinics. We will determine the utility of blood eosinophils alone, or as a composite test with FeNO, symptom score and spirometry in predicting time to first attack and use unbiased decision tree analysis to develop a prediction model for the risk of an attack. Methods:A prospective, observational, real-world, proof-of-concept study including children aged 6-16 years attending one of 5 specialist asthma clinics in London. They will undergo routine assessments (FeNO, symptom score, spirometry) and an additional POC blood test for eosinophils at every appointment, on at least 3 occasions over 12 months. Asthma attacks needing a short course of oral steroids, and unscheduled healthcare visits for asthma will be recorded prospectively. The results from the tests will be used to determine probability of an attack and time to attack for each child. Timelines: Ethical approval will be sought as soon as funding is confirmed and will be complete with site set-up in the first 3 months. Recruitment and 12-month follow-up will be undertaken over 21 months. Analysis and application for a larger national trial in the final 3 months. Impact and Dissemination:This real-world study will determine the utility of adding a POC blood test to routine asthma reviews to enable the development of an individualised risk score for a future asthma attack. This will allow targeted changes in management and closer follow-up of high-risk children to prevent attacks. The score will be validated in a larger national trial prior to implementation in routine practice. Findings from this project will be published, presented at scientific meetings, and made available via NHS Trust, University, Asthma & Lung UK communication channels to the patients and wider public.