We performed this study to assess the prevalence of sensitization to aeroallergens and to analyze the difference between prevalence rates according to children's ages and residential areas. In this nationwide cross-sectional study, first grade students of 45 elementary schools and 40 middle schools were randomly selected, and skin prick tests were performed for 18 inhalant allergens between October and November 2010. Of 7,829 analyzed subjects, 3,753 (47.9%) were sensitized to at least one aeroallergen. Sensitization to Dermatophagoides farinae was found to be the most prevalent in elementary schoolchildren (32.4%), followed by Dermatophagoides pteronyssinus, Tyrophagus putrescentiae, Japanese hop, and oak. In middle schoolchildren, D. pteronyssinus yielded the highest prevalence (42.7%), followed by D. farinae, T. putrescentiae, Japanese hop, and cat. In middle schoolchildren, the sensitization rate to aeroallergens in metropolitan, urban, and rural areas was 57.2%, 54.3%, and 49.8%, respectively (P = 0.019). In this age group, the sensitization rate in low, middle, high, and very high income groups was 53.8%, 51.8%, 59.0%, and 59.6%, respectively (P = 0.002). In conclusion, the sensitization rate is 47.9% and house dust mite is the most prevalent allergen in the pediatric population in Korea. The rate is higher in metropolitan areas and the highest income group than in rural areas and low income groups.

Background: Bronchiectasis is a chronic pulmonary disease characterized by progressive and irreversible bronchial dilatation. The aim of the present study was to investigate the etiologies and clinical features of bronchiectasis in Korean children. Methods: We performed a retrospective review of the medical records for children diagnosed with bronchiectasis between 2000 and 2017 at 28 secondary or tertiary hospitals in South Korea. Results: A total of 387 cases were enrolled. The mean age at diagnosis was 9.2 ± 5.1 years and 53.5% of the patients were boys. The most common underlying cause of bronchiectasis was preexisting respiratory infection (55.3%), post-infectious bronchiolitis obliterans (14.3%), pulmonary tuberculosis (12.3%), and heart diseases (5.6%). Common initial presenting symptoms included chronic cough (68.0%), recurrent pneumonia (36.4%), fever (31.1%), and dyspnea (19.7%). The most predominantly involved lesions were left lower lobe (53.9%), right lower lobe (47.1%) and right middle lobe (40.2%). No significant difference was observed in the distribution of these involved lesions by etiology. The forced expiratory volume in 1 s (FEV 1 ) levels were lowest in cases with interstitial lung disease-associated bronchiectasis, followed by those with recurrent aspiration and primary immunodeficiency. Conclusions: Bronchiectasis should be strongly considered in children with chronic cough and recurrent pneumonia. Long-term follow-up studies on pediatric bronchiectasis are needed to further clarify the prognosis and reduce the disease burden in these patients.

T o investigate the prevalence of asthma, allergic rhinitis, and eczema, we did a cross-sectional survey of 4,003 children aged 6-7 years (students in the 1st year of elementary school) and 4,112 students aged 13-14 years (students in the 1st year of middle school), chosen from a random sample of 45 primary and 40 middle schools across the nation. The Korean-translated modified version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used in this survey. The weighted 12-month prevalence of asthma symptoms from the questionnaires was 10.3% (95% confidence interval [CI], 9.2 to 11.4) for children aged 6-7 years and 8.3% (95% CI, 7.4 to 9.2) for children aged 13-14 years. The weighted 12-month prevalence of allergic rhinoconjuctivitis symptoms was 18.9% (95% CI, 17.5 to 20.4) for children aged 6-7 years and 19.2% (95% CI, 17.9 to 20.6) for children aged 13-14 years. The weighted 12-month prevalence of eczema symptoms was 17.9% (95% CI, 16.6 to 19.3) for children aged 6-7 years and 11.2% (95% CI, 10.1 to 12.3) for children aged 13-14 years. Compared with results from a 2000 ISAAC study, the 12-month prevalence of asthma increased from 5.8% to 10.3% in children aged 6-7 years, but there was little change (from 8.7% to 8.3%) in children aged 13-14 years. The prevalence of allergic rhinoconjunctivitis and eczema has increased considerably in both age groups.

Measuring resistance at 5 Hz using impulse oscillometry facilitates significant differentiation of baseline lung function between asthmatic and healthy children. Additionally, X may be a suitable replacement for PC20 in methacholine challenge testing.