Scientific Rationale
Over the last few decades, the increasing knowledge of the underlying inflammatory pathways in asthma has led to the development of monoclonal antibodies allowing greater disease control, minimizing OCS exposure and preventing accelerated lung function decline. High blood eosinophil counts are associated with more severe asthma exacerbations and poorer asthma control. Consequently, within the UK this biomarker is used as a key criteria for accessing biologic medications. The same threshold (typically >300 cells/uL) is currently applied to all patients, however evidence from the US that blood eosinophils differ by demographic factors such as ethnicity and gender has raised questions around whether this reflects inequality of access to biologic therapy. Further UK-focussed work is required to understand variations in blood eosinophils across the population, and their clinical implications among patients with asthma.
Research questions and objectives
The primary aim of this study is to investigate whether blood eosinophil counts differ between different demographic variables. Our secondary analysis will investigate whether demographically-adjusted blood eosinophil counts have higher predictive power when modelling asthma exacerbations than absolute blood eosinophil counts.