The relationship between airway obstruction and bronchial hyperreactivity in childhood asthma.

We performed a methacholine challenge on 118 asthmatic children to determine the relationship between airway obstruction and the degree of airway hyperreactivity. There was no significant correlation between the baseline forced expiratory volume in one second (FEV1) and the PC20 for methacholine (r = .2, P less than .05). We concluded that airway hyperreactivity in asthmatic children does not increase with increasing airway obstruction.