Abstract
OBJECTIVES: To investigate the trends in the prevalence of pediatric asthma in the western part of Japan over 40 years, using data from surveys conducted every 10 years from 1982 to 2022. DESIGN: A series of school-based epidemiological surveys conducted every 10 years. SETTING: Elementary schools in 11 prefectures in the western part of Japan. PARTICIPANTS: Children aged 6-12 years. Surveys included 55,388 children in 1982, 46,718 in 1992, 36,228 in 2002, 33,902 in 2012, and 30,024 in 2022. MAIN OUTCOME MEASURES: Prevalence of asthma, wheeze, and other allergic diseases such as allergic rhinitis, atopic dermatitis, and food allergies. RESULTS: The prevalence of asthma increased from 1982 to 2002 (boys: 3.8%-8.1%; girls: 2.5%-5.0%) and then decreased in 2012 and 2022 (boys: 6.0%-3.2%; girls: 3.5%-2.1%). The prevalence of wheeze followed a similar trend. Allergic rhinitis was the most common comorbidity, affecting 53-58% of children from 1992 onwards. Other comorbidities included atopic dermatitis, allergic conjunctivitis, and pollinosis. The prevalence of asthma was higher in urban areas than in rural areas in the early surveys, but this difference disappeared in later surveys. CONCLUSIONS: The prevalence of pediatric asthma in western Japan increased until 2002 and then decreased in subsequent surveys. Changes in environmental factors and public health measures, including those related to the COVID-19 pandemic, may have influenced these trends. Further research is needed to understand the long-term effects of these factors on asthma prevalence.