Grading severity and treatment requirements to control symptoms in asthmatic children and their relationship with airway hyperreactivity to methacholine
Amaro-Galvez, R.; McLaughlin, F.J.; Levison, H.; Rashed, N.; Galdes-Sebaldt, M.; Zimmerman, B.
Annals of Allergy 59(4): 298-302
1987
ISSN/ISBN: 0003-4738 PMID: 3310749 Document Number: 300051
Airway hyperreactivity has been proposed to be an important determinant of severity of asthma and medication needs to control symptoms in adults. In this study we tried to determine if this relationship existed in childhood asthma. One hundred and forty-five asthmatic children aged 6 to 19 years with a positive methacholine (MCH) challenge test and a baseline forced expiratory volume in one second (FEV1) of 56% to 118% predicted were studied. The MCH concentration required to decrease the FEV1 from baseline by 20% (PC20) ranged from 0.1 to 20 mg/mL (geometric mean = 1.85 mg/mL). Asthma symptoms in this population before the study ranged from 2 months to 14 years. They were followed for a mean of 10 months after the MCH challenge and then grouped into four groups according to overall severity of symptoms and treatment needed to control symptoms. The first grade was comprised of patients with intermittent symptoms only, with a respiratory tract infection (URTI), and no medication; grade 2 symptoms were severe enough to require intermittenf bronchodilators (BD); grade 3 symptoms were severe enough to require daily BD; and grade 4 symptoms were severe enough to require daily BD and seroids. Geometric means PC20 were significantly different among the four groups when they were analyzed by ANOVA P < .01. There was, however, marked overlap between the individual levels of PC20 among the four groups. There was no significant difference in mean FEV1, age, sex, or duration of symptoms among the four groups. There was no significant correlation between baseline FEV1 and the degree of airay hyperreactivity. Patients with mild asthma requiring no medication exhibited a wide range of responsiveness to MCH, and some were as sensitive to MCH as patients requiring regular therapy. We conclude that the gross overlap of individual levels of airway hyperreactivity to MCH among the groups precludes its use a predictor of treatment needs or severity.