Biomarkers in Preschool Children With Wheeze to TArget Therapy wIth inhaLed cORticosteroids (TAILOR): a Feasibility Study".

Wheezing is common in preschool children and affects quality of life. Although asthma treatments such as inhaled steroids (ICS), which reduce swelling (inflammation) in the airways are used in this age group, they are often ineffective. That is because only some preschool children have the type of inflammation (known as Type 2 inflammation) that responds to ICS, thus many children are being unnecessarily exposed to side effects. It is difficult diagnosing Type 2 inflammation through history and examination, thus other indicators are needed to ensure ICS are only given to children who will benefit. These indicators are commonly known as biomarkers, and we are trying to find out if they are useful. We want to measure three biomarkers, without changing children's treatment. The first is blood eosinophils. which can be measured using a finger prick sample (like the blood drop used for measuring sugar levels in diabetic children). The second is to determine if allergic sensitization is present to allergens that are breathed in; these will be house dust mite, grass pollen, tree pollen, cat and dog hair. The final biomarker is a molecule that is produced in the airways of preschool children with Type 2 inflammation, called nitric oxide (NO). This is easily obtained, by having children breathe through a mask and collecting their breath in a bag, measuring NO later on. The children will be followed up with monthly electronic questionnaires and 3-monthly visits (virtual or face-to-face) for a year to evaluate whether these markers individually or in combination relate to subsequent wheezing outcomes, and how acceptable the measurements are to families using a questionnaire and focus group approach. The results will form the basis of the design of a national trial of biomarker-driven therapy in such children.