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Bronchial lability and skin reactivity in siblings of asthmatic children
Insights
Boys have higher asthma rates before puberty due to greater bronchial lability, not increased atopy. This difference in airway responsiveness diminishes after puberty.
Area of Science:
- Pediatric Allergy and Immunology
- Respiratory Medicine
- Human Physiology
Background:
- Asthma prevalence is higher in prepubertal boys compared to girls.
- This sex-based difference in asthma prevalence tends to decrease after puberty.
Purpose of the Study:
- To investigate the underlying mechanisms contributing to the increased prevalence of asthma in boys.
- To compare bronchial lability and atopy between boys and girls in a pediatric population.
Main Methods:
- Assessed immediate cutaneous hypersensitivity to five allergens in children with asthma and their siblings.
- Measured maximal fall in peak expiratory flow rate after treadmill exercise (bronchial lability) in both groups.
- Analyzed differences in skin test reactivity and bronchial lability between sexes.
Main Results:
- No significant difference in skin test reactivity to allergens was observed between boys and girls in the sibling group.
- Male siblings exhibited a significantly greater percentage fall in peak expiratory flow rate after exercise compared to female siblings.
- A higher proportion of boys showed a positive bronchial lability test (≥10% or 15% fall in peak expiratory flow rate) compared to girls.
Conclusions:
- Greater bronchial lability in prepubertal boys, rather than increased atopy, likely explains the higher asthma prevalence in this age group.
- These findings suggest sex differences in airway responsiveness play a key role in early-onset asthma.
- The study highlights the importance of considering bronchial lability when examining sex-based disparities in asthma.
Abstract:
Seventy five children with asthma (42 boys and 33 girls; age range 4 years 2 months to 15 years) and 75 of their siblings (37 boys and 38 girls; age range 4 years 3 months to 17 years 8 months) were studied to elucidate the mechanisms involved in the increased prevalence of asthma in boys, a prevalence that tends to disappear after puberty. Immediate cutaneous hypersensitivity to five allergens and maximum fall in peak expiratory flow rate after six minutes of treadmill running (bronchial lability) were determined in patients and siblings. There was no significant difference between boys and girls in skin test reactivity to single or multiple allergens in the sibling group. The percentage fall in peak expiratory flow rate after exercise was significantly greater in male than in female siblings and when a positive test was defined as a fall after exercise of either 10% or 15% of the rate before exercise the number of positive tests was significantly greater in boys. The results suggest that more boys than girls in this age group have asthma because their bronchial lability is greater, and not because more boys are atopic.