Background: An association between obesity and asthma has been reported. The prevalence of airway hyperresponsiveness (AHR), results of skin prick tests, body mass index (BMI), and asthma symptoms were examined in schoolchildren.
Methods: The results of BMI (kg/m2) determination, skin prick testing, spirometry, asthma questionnaires, and methacholine challenge tests were obtained in a cross-sectional survey of 667 schoolchildren. The methacholine concentration causing a 20% fall in FEV1 (PC20) was used as the threshold of AHR. If the PC20 was less than 16 mg/mL, the subject was considered to have methachloine mediated AHR.
Results: The mean BMI was 17.1 +/- 0.09 kg/m2. The prevalence of AHR was 42.70%. The sensitization rate to common inhalant allergens was 30.3%. PC20 in children with BMIs > or = 17.1 kg/m2 was significantly lower than that in children with BMIs 17.1 kg/m2. The mean BMIs of boys and girls were not significantly different. The levels of PC20 by sex were not different. The children were grouped by sex into percentile of BMI. PC20 in boys was lower in the obese group than in the non-weight and overweight groups (p<0.05). PC20 in boys and girls with atopy was significantly lower than in those without atopy. In a multiple logistic regression model that included all of the children and adjusted for confounding variables, independent associations with AHR were seen with BMI, asthma symptoms, and atopy.
Conclusions: BMI had an association with AHR in school-age boys.