Methacholine bronchial provocation test for assessment of bronchial hyperresponsiveness in preschool children.

ABSTRACT

BACKGROUND: Bronchial hyperresponsiveness (BHR) has not been extensively performed in preschool children, possibly because of the difficulty in cooperating with the tests. We sought to determine the usefulness and safety of methacholine bronchial provocation test (MCh-BPT) for BHR assessment in preschool children. METHODS: We recruited 252 preschool children (190 healthy and 62 with wheezing) who underwent MCh-BPT at baseline. MCh-BPT was re-scheduled in case initial attempts failed. Forced expiratory volumes in 0.5 (FEV0.5), 0.75 (FEV0.75) and one second (FEV1) were measured. We recorded the provocative dose causing 15% (PD15) or 20% reduction (PD20) in FEV0.5, FEV0.75 and FEV1, thus allowing for comparison of the diagnostic value of PD15 and PD20. RESULTS: A total of 209 children [156 (82.1%) healthy, 53 (85.5%) with wheezing] successfully completed MCh-BPT. Compared with healthy children, a significantly greater proportion of children with wheezing had measurable PD15FEV0.5, PD15FEV0.75 and PD15FEV1 (P<0.01), and PD20FEV0.5, PD20FEV0.75 and PD20FEV1 (P<0.05). The sensitivity was 92.5% and 94.3% for PD20FEV1, and PD15FEV1 and the specificity was 93.6% and 93.6% respectively, for discriminating asthmatic from healthy children. CONCLUSIONS: Most preschool children successfully and safely complete MCh-BPT, with higher success rate in larger age group. PD20FEV0.5 and PD20FEV0.75 can be surrogates of PD20FEV1 among children whose expiration lasted for less than one second. PD15 has a good diagnostic value as PD20 for diagnosing of BHR in preschool children, which are also more suitable for children five years old or elder.