Wheezing in school children is not always asthma

Our objective was to study whether children with reported asthma differed from children with wheeze but without asthma, and from children with neither asthma nor wheeze, regarding lung function, bronchial hyper-responsiveness (BHR) using methacholine inhalation, exercise-induced bronchoconstriction (EIB), and skin prick test (SPT) reactivity. School children (n=2188), enrolled in a survey of asthma, were classified into three mutually exclusive groups by parental report of: asthma, wheeze, and no asthma/no wheeze. A random sample of 80 children in each group was tested (n=240). Among asthmatics, 68% (95% confidence interval (CI), 57-79) had a BHR (measured as PD20 forced expiratory volume in 1 s (FEV1) < or = 8.16 micromol using methacholine) compared to 31% (CI 20-42%) and 30% (CI 19-40%) in the wheeze and no asthma/no wheeze groups. The dose-response slope (DRS) confirmed the PD20 data and distinguished equally between groups. EIB (> or =10% fall in FEV1) was more frequent (40%, CI 29-52%) among asthmatics than among children with wheeze (12%, CI 4-19%) and no asthma/no wheeze (7%, CI 1-13%). The prevalence of at least one positive SPT was twice as high in the asthma group (58%, CI 47-69%) than in the wheeze (27%, CI 16-37%) and the no asthma/no wheeze (25%, CI 15-35%) groups. These results indicate that children with asthma differ from children with wheeze and children with no asthma/no wheeze regarding lung function, BHR, EIB, and SPT reactivity. Children with wheeze are more similar to children with no asthma/no wheeze with respect to these parameters.