Role of Direct Bronchoprovocation Test in Asthma Epidemiologic Studies

초록

Epidemiologic studies with Questionnaire depend on subjects’ response to questions. Thus, questionnaire based epidemiologic study may overestimate the true prevalence of childhood asthma since asthma-like symptoms in children are common. Direct bronchoprovocation tests are known to have both high sensitivity and negative predictive value for current asthma. This study aimed to investigate the role of methacholine challenge test in asthma epidemiological studies for estimating asthma prevalence. The subjects were 5531 elementary school children from 2009-2014 in Korea. Methacholine challenge test was performed in both asthma-symptomatic and asymptomatic subjects. Bronchial hyperresponsiveness (BHR) was defined as PC 20 ≤ 16 mg/mL. Current asthma symptoms were defined as positive response to any one of “Wheezing, current”, “Treatment, current”, or “Exercise, current”. Asthma symptoms were defined as positive response to any one of “Wheezing, current”, “Treatment, current”, “Exercise, current” or “Diagnosis ever”. True asthma was defined as asthma symptoms with proved bronchial hyperresponsiveness. Results: Total of 4791 children (2348 male, 2443 female) aged from 7 to 12 years was included in the analysis. The prevalence of “Wheezing, ever” “Wheezing, current” “Diagnosis, ever” “Treatment, current” “Exercise, current” were 19.6%, 6.9%, 10.0%, 3.3% and 3.5%, respectively, in cross-sectional study of Korean elementary school students. Current asthma symptoms was 9.6%. The prevalence of BHR in the general population of children was 14.5%. The prevalence of BHR in children with “Wheezing ever” “Wheezing current”, “Treatment, current”, and “Exercise, current” were 22.3%, 30.5%, 28.8%, and 29.9%, respectively. BHR was 26.1% in current asthma symptoms. True asthma with both asthma symptoms and bronchial hyperresponsiveness was 3.5%. Conclusion: The Korean version of ISAAC questions for diagnosis of asthma has low sensitivity to BHR.