Background It is challenging to diagnose asthma in preschool children. The asthma predictive index (API) has been used to predict asthma and decide whether to initiate treatment in preschool children. Purpose This study aimed to investigate the association between questionnaire-based current asthma with API, pulmonary function, airway hyperreactivity (AHR), fractional expiratory nitric oxide (FeNO), and atopic sensitization in preschool children. Methods We performed a population-based cross-sectional study in 916 preschool children aged 4–6 years. We defined current asthma as the presence of both physician-diagnosed asthma and at least one wheezing episode within the previous 12 months using a modified International Study of Asthma and Allergies in Childhood questionnaire. Clinical and laboratory parameters were compared between groups according to the presence of current asthma. Results The prevalence of current asthma was 3.9% in the study population. Children with current asthma showed a higher rate of positive bronchodilator response and loose and stringent API scores than children without current asthma. The stringent API was associated with current asthma with 72.2% sensitivity and 82.0% specificity. The diagnostic accuracy of the stringent API for current asthma was 0.771. However, no intergroup differences in spirometry results, methacholine provocation test results, FeNO level, or atopic sensitization rate were observed. Conclusion The questionnaire-based diagnosis of current asthma is associated with API, but not with spirometry, AHR, FeNO, or atopic sensitization in preschool children.

Sensitization plays important roles in the development of asthma and AR in children. We elucidated the association between sensitization patterns and allergic diseases. A cohort of 548 children was enrolled from the Panel Study of Korean Children (PSKC) study. Skin prick tests for 18 common allergens, blood tests, and methacholine bronchial challenge tests were performed at age 7. The Korean version of International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used to evaluate the presence of allergic diseases. The sensitization rate was 46.4%. Sensitization to indoor allergens (Der f, Dermatophagoides pteronyssinus [Der p], cat epithelium, dog dander, cockroach) showed an association with symptoms of asthma (adjusted odds ratio [aOR], 2.39; 95% confidence intervals [95% CIs], 1.10-5.23) and allergic rhinitis (AR, aOR 2.08, 95% CIs 1.42-3.06) in the preceding 12 months. In contrast, sensitization to outdoor allergens (grass mixture, alder, birch, oak, Japanese hop, Mugwort, ragweed, hazel) was associated with AR diagnosis only (aOR 2.40, 95% CIs 1.30-4.41). The number of sensitized allergens was associated with a lifetime diagnosis and with symptoms in the preceding 12 months of AR and asthma, but not with BHR. A higher degree of sensitization to indoor and outdoor allergens was associated with symptoms in the preceding 12 months of asthma and AR. The sensitization patterns including allergen type, number, and degree of sensitization are helpful for interpreting the association between sensitization patterns and asthma/AR and identifying the pathophysiologies and diverse phenotypes of allergic diseases.

Purpose: To investigate whether prenatal exposure to indoor fine particulate matter (PM2.5) and environmental tobacco smoke (ETS) affects susceptibility to respiratory tract infections (RTIs) in infancy, to compare their effects between prenatal and postnatal exposure, and to determine whether genetic factors modify these environmental effects. Methods: The study population consisted of 307 birth cohort infants. A diagnosis of RTIs was based on parental report of a physician's diagnosis. Indoor PM2.5 and ETS levels were measured during pregnancy and infancy. TaqMan was used for genotyping of nuclear factor erythroid 2-related factor(Nn2) (rs6726395), glutathione-S-transferase-pi (GSTP) 1 (rs1695), and glutathione-S-transferase-mu (GSTM) 1. Microarrays were used for genome-wide methylation analysis. Results: Prenatal exposure to indoor PM2.5 increased the susceptibility of lower Fills (LRTIs) in infancy (adjusted odds ratio [aOR]=2.11). In terms of combined exposure to both indoor PM2.5 and ETS, prenatal exposure to both pollutants increased susceptibility to LRTIs (aOH=6.56); however, this association was not found for postnatal exposure. The Nrf2 GG (aOR=23.69), GSTM1 null (aOR=8.18), and GSTP1 AG or GO (aOR=7.37) genotypes increased the combined LRTIs-promoting effects of prenatal exposure to the 2 indoor pollutants. Such effects of prenatal indoor PM(2.)5 and ETS exposure were not found for upper RTIs. Conclusions: Prenatal exposure to both indoor PM2.5 and ETS may increase susceptibility to LRTIs. This effect can be modified by polymorphisms in reactive oxygen species-related genes.