Possible presence of undiagnosed asthma in children in Japan.

Abstract

Asthma diagnosis in children is occasionally challenging, and the issue of undiagnosed asthma before adolescence has been poorly studied in Japan. The present study was conducted to investigate the possible presence of undiagnosed asthma in the general population of children living in a rural area of Japan. The participants comprised 120 fourth graders aged 9-10 years (boys/girls: 63/57) attending five elementary schools in Yawatahama, Ehime, Japan. All the children underwent respiratory function tests and fraction of exhaled nitric oxide (FeNO) measurements. Based on the results of a questionnaire, the children were also categorized into groups depending on their allergic diseases.The authors assessed the results of both the respiratory function tests and the FeNO measurements for children who were classified into the nonallergic group. A total of 76 (63%) children, who completed the tests appropriately, were included in the analysis. According to the report, among the 24 children in the nonallergic group, six (25%) showed abnormalities in respiratory tests. One had an abnormal % forced vital capacity (%FVC; <80%), three had abnormalities in both forced expiratory volume in 1 sec (FEV1)/FVC (<80%) and % maximal mid-expiratory flow (<65%), three had concave flow-volume curves, and one had a high FeNO measurement (41 ppb). A certain proportion of Japanese elementary school children, categorized as having no allergy, showed respiratory function test abnormalities. A follow-up study is needed to determine the prognosis and outcomes of the children with these abnormalities.