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

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.

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 (FEV_0.5), 0.75 (FEV_0.75) and one second (FEV₁) were measured. We recorded the provocative dose causing 15% (PD₁₅) or 20% reduction (PD₂₀) in FEV_0.5, FEV_0.75 and FEV₁, thus allowing for comparison of the diagnostic value of PD₁₅ and PD₂₀.

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 PD₁₅FEV_0.5, PD₁₅FEV_0.75 and PD₁₅FEV₁ (P<0.01), and PD₂₀FEV_0.5, PD₂₀FEV_0.75 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.

Most preschool children successfully and safely complete MCh-BPT, with higher success rate in larger age group. PD₂₀FEV_0.5 and PD₂₀FEV_0.75 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.