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Atopy in childhood. III. Relationship with pulmonary function and airway responsiveness
M R Sears1, B Burrows, G P Herbison
1Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
Insights
In children, atopy (allergic tendency) is linked to poorer lung function and increased airway hyperresponsiveness. This connection is particularly strong in those allergic to house dust mites or cat dander.
Area of Science:
- Pediatric Pulmonology
- Allergy and Immunology
- Respiratory Medicine
Background:
- The interplay between atopy, lung function, and airway hyperresponsiveness in children remains unclear.
- Understanding these relationships is crucial for diagnosing and managing pediatric respiratory conditions.
Purpose of the Study:
- To investigate the associations between atopy, baseline pulmonary function, and airway hyperresponsiveness in 13-year-old children.
- To determine if atopy influences the relationship between lung function and airway responsiveness.
Main Methods:
- A cohort of 662 New Zealand children (age 13) completed respiratory questionnaires, skin-prick tests for 11 allergens, spirometry, and methacholine challenge tests.
- Statistical analyses examined correlations between atopy, FEV1/VC ratios (forced expiratory volume in 1 second/vital capacity), and airway responsiveness.
Main Results:
- A significant link was found between atopy and reduced baseline pulmonary function (lower FEV1/VC ratios).
- Lower FEV1/VC ratios were associated with increased airway responsiveness, even in children without diagnosed asthma or wheeze.
- The association between lung function and airway responsiveness was stronger in atopic children, especially those allergic to house dust mite and cat dander.
- Atopy and impaired lung function were additive predictors of airway responsiveness.
Conclusions:
- Atopy, particularly to house dust mite and cat dander, is correlated with reduced pulmonary function (FEV1/VC) in children.
- Airway responsiveness is associated with impaired lung function, and this relationship is mediated by atopy.
- Atopy and diminished lung function act together to increase the likelihood of airway responsiveness in children.
Abstract:
The relationship between atopy and pulmonary function in children, and how these relate directly or indirectly to airway hyperresponsiveness, is uncertain. We have examined these relationships in a sample of 13-year-old children. A questionnaire on respiratory symptoms, skin-prick tests to 11 common allergens, spirometry and an abbreviated methacholine challenge test were completed by 662 members (341 boys) of a birth cohort of New Zealand children followed longitudinally to age 13. There was a significant relationship between the presence and degree of atopy, and baseline pulmonary function. Low FEV1/VC ratios were associated with a greater likelihood of airway responsiveness, not only in subjects with diagnosed asthma, but also in the full cohort and in the sub-group of 426 children who denied asthma or current wheeze. The relationships between baseline FEV1/VC and airway responsiveness were stronger in atopic than in non-atopic children, with the strongest relationships in children sensitive to house dust mite and/or cat dander. In the presence of atopy, progressively lower levels of lung function were strongly associated with a higher prevalence of airway responsiveness (P<0.001). In non-atopic subjects, only those with the most impaired lung function (FEV1/VC < 75%) showed any substantive prevalence of airway responsiveness. The relationship between the degree of atopy and the FEV1/VC ratio, although significant in univariate analysis, became completely non-significant after accounting for airway responsiveness. In 13-year-old children, atopy, especially to house dust mite and cat dander, was correlated with pulmonary function expressed as FEV1/VC ratio. Airway responsiveness likewise correlated with impaired baseline lung function. The apparent relationship of lung function to atopy occurred primarily as a result of the relationship between atopy and airway responsiveness. Atopy and impaired lung function were additive factors predicting airway responsiveness.