Table 2. Demographics of the study population.

Variables		Values
Number		667
Age (yr)		8.90 ± 2.59
Sex (male)		445/667 (66.7)
Height (cm)		136.15 ± 15.69
Weight (kg)		35.81 ± 14.34
Body mass index (kg/m2)		18.56 ± 3.58
Asthma severity
	Mild intermittent	251/667 (37.6)
	Mild persistent	260/667 (39.0)
	Moderate persistent	152/667 (22.8)
	Severe persistent	4/667 (0.6)
Positive bronchodilator responses of FEV1 (≥ 12%)		140/442 (31.7)
Methacholine PC20 (< 16 mg/mL)		498/498 (100.0)

Values are presented as mean ± standard deviation or number (%).

FEV1, forced expiratory volume in 1 second; PC20, cumulative methacholine dose that caused a 20% reduction in FEV1.