# Surveys on the prevalence of pediatric asthma in Japan: A comparison between the 1982, 1992, 2002, 2012, and 2022 surveys conducted in the same region using the same methodology (WJSAAC PhaseⅠ∼Ⅴ)

## TL;DR

This study tracks asthma prevalence in Japanese children from 1982 to 2022, showing an increase until 2002 followed by a decline.

## Contribution

Long-term trends in pediatric asthma prevalence in Japan using consistent methodology over 40 years.

## Key findings

- Asthma prevalence in children rose until 2002 then declined by 2022.
- Allergic rhinitis was the most common comorbidity since 1992.
- Urban-rural asthma prevalence differences disappeared in later surveys.

## Abstract

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.

A series of school-based epidemiological surveys conducted every 10 years.

Elementary schools in 11 prefectures in the western part of Japan.

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.

Prevalence of asthma, wheeze, and other allergic diseases such as allergic rhinitis, atopic dermatitis, and food allergies.

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.

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.