Bronchial Hyperresponsiveness to Methacholine in Children Under 4 Years with Recurrent Bronchitis

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Objective To evaluate bronchial hyperresponsiveness in children under 4 years old with recurrent wheezing bronchitis, and to determine if its presence or absence can predict subsequent progression to a transient or persistent wheezing bronchitis phenotype. Population and methods A bronchial challenge test was performed with methacholine using a modified tidal volume method without sedation, in a group of patients from 8 to 47 months of age with recurrent wheezing bronchitis and a control group of healthy children. A decrease in oxygen saturation of ≥5% or an increase in respiration rate of >50% [PCwheeze (PCw)] was considered a positive response. The patients were subsequently clinically followed up to assess their progress. Results A total of 63 patients and 16 controls were studied (mean age 23.9 compared to 25.2 months). The PCw in 43 (68%) children from the bronchitis group was lower than the control group (≤4 mg/mL), ( P<.001). No significant adverse effects were observed on performing the test. After a mean follow-up of 28.5 months, completed in 49 of the patients, no differences were seen between the presence of bronchial hyperresponsiveness at the beginning of the study and the subsequent progression to transient, infrequent or frequent wheezing ( P=.63). Conclusions A high percentage of children under 4 years old with wheezing bronchitis had a bronchial hyperresponse. Subsequent progression to transient or persistent wheezing bronchitis phenotype is not associated with bronchial hyperresponsiveness.