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Notes: Background In most epidemiological survey studies, only subjective symptoms and past medical history of asthma have been used as diagnostic criteria. Even though a questionnaire survey can be performed in a large population study at low cost, limitations such as lack of objectivity and poor predictability in non-specific bronchial hyperresponsiveness cannot be avoided.Objectives The purpose of this study was to elucidate the prevalence of current asthma based on questionnaires and methacholine bronchial provocation test, and the prevalence of atopy in Korea.Methods We performed modified ATS respiratory questionnaires and allergen skin-prick test with 10 common inhalant allergens among 3219 subjects aged 7–19 years in Seoul and a rural part of a small city, Chungju in Korea. Methacholine bronchial provocation tests were also performed among those who had asthma symptoms according to the questionnaire. The criteria of asthma was presence of both asthma symptoms and non-specific bronchial hyperresponsiveness. Atopy was defined as when an allergen induced weal size is same or larger than that caused by histamine.Results The prevalence of asthma based on questionnaires and methacholine bronchial provocation tests was 4.6%, while the prevalence of wheeze was 8.2% and 19.3% of total population complained of one or more respiratory symptoms related to asthma on the questionnaires. There was no significant difference according to age, sex and living area. The mean prevalence of atopy was 35.0% and the most common allergens were Dermatophagoides farinae (30.9%), Dermatophagoides pteronyssinus (27.5%), cat fur (20.4%) and cockroach (11.8%). The atopy prevalence in Chungju area was higher than that in Seoul and males showed a higher prevalence than females. The asthma prevalence was higher among atopies (6.8%) than among non-atopies (2.7%). None of questionnaire items were enough to predict the presence of bronchial hyperresponsiveness in terms of sensitivity, specificity and positive predictive value.Conclusion The prevalence rate of current asthma in Korea was 4.6% and the prevalence rate of atopy in Korea was 35.0%. Questionnaire-based surveys are not enough to predict the actual prevalence of asthma.

Notes: Background There have been many studies concerning pathological changes in bronchial mucosa from asthmatics; however, few studies has been carried out to evaluate pathological changes according to the severity of asthma.Objective This study was designed to evaluate the cellular components in bronchoalveolar lavage fluid (BALF) and histologicai abnormalities in asthmatics according to the severity ot asthma.Methods Bronchoalveolar lavages, bronchoscopic biopsies and ultrastructural examinations were performed in 13 asthmatics and 11 (BAL) or four (biopsies) non-asthmatic controls. The proportions of epithelial cells and eosinophils in BALF were significantly increased in asthmatics and showed significant correlations with PC20Meth which reflects bronchial hyperresponsiveness. Light microscopic examination revealed loss of epithelium, inllammatory cell infiltrations and thickening of the basement membrane which also showed significant correlation with PC20Meth. Hypertrophy of airway smooth muscles and hyperplasia of mucous glands were prominent in asthmatics but there was no difference according to the severity of asthma. Ultra-structural examination revealed that basement membrane thickening on light microscopic examination is due to the increased subepithelial collagen deposition with normal thickeness of basal lamina.Conclusion These data suggest that loss of epithelial cells, infiltration of inflammatory cells, especially eosinophils, and increased deposition of subepithelial collagen play major roles in determining the severity of asthma and non-specific bronchial hyperresponsiveness.