High levels of urinary eosinophil protein X in young asthmatic children predict persistent atopic asthma

Levels of urinary eosinophil protein X (U‐EPX) and eosinophil counts were measured in 32 children (12–36 months of age) who were hospitalized for acute asthma, and the U‐EPX levels were measured in 20 healthy children of the same age. The ability of these parameters to predict persistent asthma (at least one wheezing episode during the last 6 months) and atopic asthma (a positive skin‐prick test [SPT]), was evaluated at a follow‐up 2 years later. On admission, levels of U‐EPX were higher in children with asthma (median: 120 µg/mmol of creatinine; quartiles: 67–123 µg/mmol of creatinine) than in controls (60 µg/mmol of creatinine, 38–74 µg/mmol of creatinine; p< 0.001). The U‐EPX level was higher in those with persistent atopic asthma at follow‐up (173 µg/mmol of creatinine, 123–196 µg/mmol of creatinine, n = 16), than in those with persistent non‐atopic asthma (73 µg/mmol creatinine, 46–105 µg/mmol of creatinine, n = 8; p< 0.05), and higher than in those with transient asthma (no symptoms at follow‐up) (106 µg/mmol creatinine; 42–167 µg/mmol of creatinine, n = 8; p< 0.05). By multiple logistic regression analysis, U‐EPX was the only parameter able to predict persistent atopic asthma; eosinophil counts, parental atopy, age or gender could not. Parental atopy was the only parameter predictive for persistent asthma, regardless of atopic status. In conclusion, levels of U‐EPX, but not eosinophil counts, measured in young children hospitalized with acute asthma can predict the persistence of atopic asthma 2 years later.