In selected asthma patients, blood eosinophil count predicts response to inhaled corticosteroids and certain biologic treatments. Despite its critical significance, fundamental elements of eosinophil behavior in asthma have yet to be investigated. This study was to look into the conduct of blood eosinophils in a population by comparing their distribution to that of the general population and looking at their intra-individual variability over time about hospital episodes (emergency department visits and hospitalizations) in clinical practice. The Majorca Real-Life Investigation in COPD and Asthma cohort studied the distribution and variability of 35,703 eosinophil determinations in 10,059 stable asthma patients (MAJORICA). Researchers compared the distribution of eosinophils in the asthma group to a control sample of 8,557 people from the general community. Correlations, ROC curves, and multiple regression analysis were used to examine eosinophil variability and hospital episodes.

The Eosinophil Variability Index (EVI) was calculated as (Eosmax-Eosmin/Eosmax) x 100%. The asthma population’s findings were re-tested in a well-characterized external asthma cohort. The asthma population had greater eosinophil count levels and variability than the overall population (p-value 0.001). The variability data had a stronger link to hospitalizations than the counting numbers. They connected absolute counting values were more strongly with hospital episodes than an EVI≥50%. The external cohort confirmed these findings. Eosinophil variability determines the risk of any hospital episode in asthma patients better than the absolute counts’ numbers currently used to target specific medications.