BRONCHIAL RESPONSIVENESS IN CHILDREN AND ADOLESCENTS - A COMPARISON BETWEEN PREVIOUSLY ASTHMATIC, CURRENTLY ASTHMATIC, AND NORMAL SUBJECTS

The aim of this study was to examine the degree of bronchial responsiv eness in previously asthmatic subjects. Of 253 patients, born within 1 964-1974, followed in the pediatric department at the University hospi tal in Copenhagen, 224 subjects (89%) were successfully contacted by t elephone; of these 195 complained of persistent asthma and 29 (13%) ha d had no asthmatic symptoms for at least 2 years. On the basis of the degree of respiratory symptoms, 58 individuals were examined at the ou tpatient clinic. Of these, (1) 19 were previously asthmatics, (2) 20 h ad current mild asthma, and (3) 19 had current severe asthma. Furtherm ore, 19 healthy individuals, age-matched with the preceding asthmatic subjects, were selected as controls. In all subjects, skin prick tests , lung function tests, and bronchial challenge tests with inhaled hist amine and bronchodilator were performed. Furthermore, the subjects mea sured their peak expiratory flow (PEF) twice daily during a period of 4 weeks. Of the 39 current asthmatic subjects, 82% had a PC20 less-tha n-or-equal-to 8 mg/ml, whereas all previously asthmatic subjects and t he controls had a PC20 > 8 mg/ml. The degree of bronchial responsivene ss as indicated by the dose-response slope (DRS), the percentage chang e in forced expiratory volume in 1 sec (FEV1) per inhaled mumol of his tamine, was found to be significantly higher in previously asthmatic p atients (median logDRS 0.1 DELTA%FEV1/mumol) than in controls (median logDRS -0.4 DELTA%FEV1/mumol) (p < 0.001). Furthermore previously asth matic subjects had significantly increased change in FEV1 after inhala tion of bronchodilator and peak expiratory flow variability compared t o controls. These findings suggest that apparently asymptomatic previo usly asthmatic subjects have increased airway variability.