Objective: To determine the prevalence of atopy and bronchial hyper-reactivity (BHR) and their relationship with wheezing and diagnosed asthma reported in schoolchildren.
Material and methods: In Cracow, 1347 schoolchildren (9.7 +/- 0.7 yrs of age) were surveyed with ISAAC questionnaire. Skin prick tests with 7 aeroallergens and the exercise challenge test for BHR evaluation were carried out. Atopy was established when a positive skin reaction with at least one allergen occurred. The BHR was confirmed in presence of at least 15% decrease of the relative post-exercise peak expiratory flow (D% PEF) or wheezing during or immediately after exercise.
Results: Atopy was found in 26.2% of schoolchildren, with a two-fold higher risk in boys/odds ratio (OR) = 2.14; 95% confidence interval (CI) (1.59-2.86)/. In the group of atopic children, wheeze in the last year and diagnosis of asthma occurred significantly more often. The risk of wheeze in last year related to the type of sensitizing allergen and was highest for Der. f./OR = 6.1; 95% CI (3.78-10.16)/, medium for allergens of trees, dog's fur, Der. p., cat's fur and grasses/OR = 5.17; 95% CI (2.27-11.76), OR = 4.36; 95% CI (2.35-8.13), OR = 4.00; 95% CI (3.12-8.01), OR = 3.86; 95% CI (2.18-6.82), OR = 2.58; 95% CI (1.50-4.45), respectively/. In case of Alternaria allergens no correlation with wheeze was observed/OR = 2.71; 95% CI (0.88-8.31)/. BHR was identified in 12.4% of schoolchildren and demonstrated a significant correlation with that reported in the questionnaire: wheeze in the last year/OR = 2.28; 95% CI (1.25-4.14)/, diagnosis of asthma/OR = 2.96; 95% CI (1.38-6.34)/and post-exercise wheeze/OR = 3.17; 95% CI (1.60-6.27)/. Moreover, a significant correlation was demonstrated between atopy and BHR/OR = 1.85; 95% CI (1.22-2.79)/. In the group of children without wheeze in the past and without diagnosis of asthma, BHR was significantly higher in atopic children (positive skin test to in-door allergens) comparing to non-atopic ones, mean D% PEF values were 3.95%, -0.39%, respectively (p. = 0.0014).
Conclusions: In children, there is a significant correlation between atopy and BHR, modified by individual history of wheeze or asthma, sex and allergen type.