Correlation between the clinical classification of bronchial asthma severity and the methacholine test in children.

ABSTRACT

The purpose of this study was to validate the Methacholine Bronchial Challenge Test in its different degrees and to compare them with the different clinical classifications of bronchial asthma. Fifty-four child asthmatic patients over 6 years of age from the Respiratory Outpatient Clinic at La Union Hospital (Chile) were submitted to the clinical classification of bronchial asthma and later to the Methacholine Bronchial Challenge Test, which classified the children as mildly, moderately or severely hyperreactive to the test. In mildly asthmatic children, the Methacholine Test showed both a high sensitivity (100%) and specificity (92.3%). In moderately asthmatic children, the sensitivity decreased to 84.5%, whilst the specificity was maintained (92.3%). In severely asthmatic children, however, the sensitivity decreased to 53.5%, whilst the specificity increased 97.2%. The latter could be explained as a consequence of the previous exposure of this group of children to either inhaled or oral corticoids. According to our experience, the Methacholine Test is not only useful for the diagnosis of bronchial hyperreactivity in dubious cases, but also for contributing together with the clinical findings to the adequate classification of these patients.