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 microg/mmol of creatinine; quartiles: 67-123 microg/mmol of creatinine) than in controls (60 microg/mmol of creatinine, 38-74 microg/mmol of creatinine; p< 0.001). The U-EPX level was higher in those with persistent atopic asthma at follow-up (173 microg/mmol of creatinine, 123-196 microg/mmol of creatinine, n = 16), than in those with persistent non-atopic asthma (73 microg/mmol creatinine, 46-105 microg/mmol of creatinine, n = 8; p< 0.05), and higher than in those with transient asthma (no symptoms at follow-up) (106 microg/mmol creatinine; 42-167 microg/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.