Methacholine challenge and sputum induction - Reply

AUTHORS\u2019 REPLY We would like to thank Drs Labiris and Hargreave for their interesting comments on our article. They have emphasised the variability in the data and the fact that the p values for neutrophils and macrophages were near significance. Moreover, they have provided the results of a power analysis for paired continuous data showing that the study is underpowered to reach solid conclusions. We agree that their comments are valid both for the variability of the data and that the p value was near significance for neutrophils and macrophages. However, the p value for eosinophils was far from the significance level (p = 0.49). This is important because the aim of the study was to evaluate the influence of methacholine challenge on overall sputum cellularity but, in particular, on eosinophils which are considered the most relevant inflammatory cell in bronchial asthma. We are confident that a methacholine inhalation challenge carried out one hour before sputum induction in asthmatic subjects does not alter the eosinophil count in induced sputum, and that this result is important for both clinical practice and clinical trials involving patients with asthma