Longitudinal Preschool Wheeze Biomarker Study

Research Question: Can the research team identify simple bedside tests that can give quick, accurate results while being acceptable to parents and children, and can these tests be successfully used in clinical practice, to decide treatment for preschool wheeze? Participants will be asked to do these simple tests- skin prick test, finger prick blood test, breathing test, throat swab, and a test to catch their phlegm. The researchers will use two tests to identify children who are likely to respond to inhaled steroids: skin tests for allergies and a finger prick blood test. To identify children with bacterial infections in their lungs, where antibiotics will be useful, the team will obtain a sample of sputum (phlegm) after a salty mist inhalation (saline nebuliser), and will test the accuracy of a throat swab that detects bacteria. The research team will also test how cells called neutrophils work in children without allergies or infection with the same finger prick blood test above. A breathing test called forced oscillation will be used to identify children who may respond to their reliever "blue" inhaler during wheezing attacks. The research team will also recruit a small number of children, for a trial in which their treatment will be guided by their test result, to see if parents are willing to take part in such a study, before designing a larger trial. This study will be the first to show that new tests can identify different types of preschool wheezing and can be used to plan treatment based on individual children's needs. Researchers will compare to see if children who have their treatment based on the simple bedside tests do better than the children who are just given inhaled steroids.