Serum eosinophil cationic protein as a predictor of wheezing after bronchiolitis

We have evaluated the role of eosinophil cationic protein (ECP) concentrations in serum in predicting wheezing after bronchiolitis, during infancy and early childhood. A prospective study at a university hospital serving all pediatric patients in a defined area was designed. Serum ECP concentrations were measured in 92 infants under the age of 2 years on admission for acute bronchiolitis, and 6 and 16 weeks after hospitalization. Nebulized anti‐inflammatory therapy was initiated during hospitalization: 32 patients received cromolyn sodium and 32 patients received budesonide for 16 weeks; 30 control patients received no maintenance therapy. The numbers of subsequent physician‐diagnosed wheezing episodes and hospital admissions for obstructive airway disease were recorded during 16 weeks of follow‐up. At entry, 14 of 92 (15%) children had high (≥16 μg/L) levels of ECP in their serum. During the 16‐week follow‐up period, this group of patients had significantly more physician‐diagnosed episodes of wheezing (86% vs. 43%, P < 0.01) and hospital admissions for wheezing (64% vs. 19%, P = 0.001) than those with serum levels of ECP < 16 μg/L. The number of patients with serum ECP ≥ 8 μg/L was 25 (27%); 76% of this group developed physician‐diagnosed wheezing (P < 0.01), and 48% had hospital admissions for wheezing (P < 0.01). Serum ECP levels decreased significantly with respect to time after bronchiolitis and did not differ among the three intervention groups. We conclude that a high serum ECP concentration during the acute phase of bronchiolitis is a specific but insensitive predictor of wheezing after bronchiolitis. Pediatr. Pulmonol. 1997; 23:397–403. © 1997 Wiley‐Liss, Inc.