Relation of two different subtypes of croup before age three to wheezing, atopy, and pulmonary function during childhood: A prospective study

Objective. Some retrospective evidence suggests that children with a histor y of croup may be at increased risk of subsequently developing asthma, atop y, and diminished pulmonary function. The objective of this study was to de termine the long-term outcome of croup (as diagnosed by a physician) in ear ly life. Methods. Lower respiratory illnesses (LRIs) in the first 3 years of life we re assessed in 884 children who were enrolled in a large longitudinal study of airway diseases at birth. Pulmonary function tests, markers of atopy, a nd wheezing episodes were studied at different ages between birth and 13 ye ars. Results. Ten percent of children had croup with wheeze (Croup/Wheeze), 5% h ad croup without wheeze (Croup/No Wheeze), 36% had another LRI (Other LRI), and 48% had no LRI. Respiratory syncytial virus was more frequently isolat ed in children with Croup/Wheeze and Other LRI than in those with Croup/No Wheeze. There was no association between croup in early life and markers of atopy measured during the school years. Only children with Croup/ Wheeze a nd with Other LRI had a significant risk of subsequent persistent wheeze la ter in life. Significantly lower levels of indices of intrapulmonary airway function were observed at ages <1 (before any LRI), 6, and 11 years in chi ldren with Croup/ Wheeze and Other LRI compared with children with No LRI. Conversely, inspiratory resistance before any LRI episode was significantly higher in infants who later developed Croup/No Wheeze than in the other 3 groups. Conclusions. We distinguish 2 manifestations of croup with and without whee zing. Children who present with croup may or may not be at increased risk o f subsequent recurrent lower airway obstruction, depending on the initial l ower airway involvement, and preillness and postillness abnormalities in lu ng function associated with this condition.