Comparison of two published definitions of sputum neutrophilia show clinical measures of disease are more severe in neutrophilic asthma (NA) than non-neutrophilic asthma (NNA) using >40% sputum neutrophils as the definition of disease

<b>Background:</b> Sputum neutrophils are associated with poor disease outcome in asthma, yet there is a lack of a concordance for the definition of neutrophilia in asthma. Gaining an agreed definition of NA may guide clinical care <b>Methods:</b> Clinical data was collected from 138 non-eosinophilic asthma patients within the Wessex Severe Asthma Cohort Study. Data were split by two definitions of neutrophilia; &gt;40% sputum neutrophils (1) and &gt;61% sputum neutrophils (2). Differences in NA vs NNA were explored for each definition of neutrophilia using frequency statistics and Mann Whitney U analysis. <b>Results:</b> <b>Conclusion:</b> Sputum neutrophilia is associated with poor clinical outcome in asthma. Using a definition of &gt;40% sputum neutrophils to define neutrophilia generates a more clinically distinct population of NA than a definition of &gt;61% sputum neutrophils in our cohort. 1. Hastie, JACI 125(5): 1028-1036 e101 2. Simpson, Respirology 11(1): 54-61