PREVALENCE OF CHILDHOOD ASTHMA BASED ON QUESTIONNAIRES AND METHACHOLINE BRONCHIAL PROVOCATION TEST IN KOREA

Background In most epidemiological survey studies, only subjective sym ptoms and past medical history of asthma have been used as diagnostic criteria. Even though a questionnaire survey can be performed in a lar ge population study at low cost, limitations such as lack of objectivi ty and poor predictability in non-specific bronchial hyperresponsivene ss cannot be avoided. Objectives The purpose of this study was to eluc idate the prevalence of current asthma based on questionnaires and met hacholine bronchial provocation test, and the prevalence of atopy in K orea. 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, C hungju in Korea. Methacholine bronchial provocation tests were also pe rformed among those who had asthma symptoms according to the questionn aire. 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 hi stamine. Results The prevalence of asthma based on questionnaires and methacholine bronchial provocation tests was 4.6%, while the prevalenc e of wheeze was 8.2% and 19.3% of total population complained of one o r more respiratory symptoms related to asthma on the questionnaires. T here was no significant difference according to age, sex and living ar ea. The mean prevalence of atopy was 35.0% and the most common allerge ns were Dermatophagoides farinae (30.9%), Dermatophagoides pteronyssin us (27.5%), cat fur (20.4%) and cockroach (11.8%). The atopy prevalenc e in Chungju area was higher than that in Seoul and males showed a hig her prevalence than females. The asthma prevalence was higher among at opics (6.8%) than among non-atopics (2.7%). None of questionnaire item s were enough to predict the presence of bronchial hyperresponsiveness in terms of sensitivity, specificity and positive predictive value. C onclusion The prevalence rate of current asthma in Korea was 4.6% and the prevalence rate of atopy in Korea was 35.0%. Questionnaire-based s urveys are not enough to predict the actual prevalence of asthma.