Association of urinary eosinophilic protein X at age 3 years and subsequent persistence of wheezing and asthma diagnosis in adolescence.

BACKGROUND

Wheezing is common in early life, but most children stop wheezing by school age. However, the prediction of course of wheezing through childhood is difficult.

OBJECTIVE

To investigate whether urinary EPX (a marker of eosinophil activation) in children at age 3 years may be useful for the prediction of wheeze persistence and future asthma diagnosis.

METHODS

U-EPX was measured at age 3 years (radioimmunoassay) in 906 participants in the population-based birth cohort. Children attended follow-ups to age 16 years. We investigate the discriminative ability of u-EPX and other factors in predicting asthma diagnosis at age 16 using receiver operating characteristic [ROC] curves.

RESULTS

Of 613 children with follow-up information at age 16, 511 had data on u-EPX at age 3 and asthma diagnosis at age 16 years; of those; 133 (21.7%) had asthma. Based on longitudinal data, children were assigned to wheeze clusters: No wheeze (NWZ), early transient (ETW), late-onset (LOW), intermittent (INT) and persistent wheeze (PEW). U-EPX levels differed significantly between different wheeze clusters (p = .003), with clusters characterised with persistent symptoms having higher u-EPX. In the whole cohort, the best performing classification model for asthma diagnosis at age 16 years included sex, u-EPX, sensitisation and wheeze (area under the curve (AUC) = 0.82, 95% CI: 0.76-0.88). u-EPX and allergic sensitisation alone had similar predictive power (AUC [95%CI]: 0.64 [0.58-0.71] and 0.65 [0.60-0.71]). The best performing classification model for asthma prediction among children with doctor-confirmed wheeze in the first 3 years included child's u-EPX and sensitisation at age 3 years, sex, gestational age and maternal atopy (AUC: 0.76, 95%CI: 0.67-0.85).

CONCLUSIONS

Early-life u-EPX may be a useful non-invasive marker for asthma prediction in adolescence.