Original Abstract
BACKGROUND: Asthma is a global chronic respiratory disease whose development and exacerbation are significantly influenced by modifiable environmental and occupational exposures, such as air pollution and occupational asthma triggers. Understanding the burden attributable to these factors among children, adolescents, and young adults is essential for effective prevention strategies. While prior epidemiological assessments have characterized the overall asthma burden, there remains a scarcity of focused investigations that examine the disease burden specifically associated with these risk factors in the 5-39-year age group. Notably, a comprehensive analysis utilizing the GBD 2021 dataset to quantify trends, disparities, and future projections of environment- and occupation-related asthma in this vulnerable population remains limited. METHODS: This study analyzed data from the GBD 2021 study to examine global, regional, and national trends in asthma prevalence, incidence, mortality, and disability-adjusted life years (DALYs) among individuals aged 5-39 years (children and young adults) between 1990 and 2021. Analyses were stratified by age group, gender, and socio-demographic index (SDI). We quantified trends in asthma burden using the estimated annual percentage change (EAPC); conducted a decomposition analysis to identify driving factors for changes from 1990 to 2021 among children and young adults aged 5-39 years; and summarized risk-attributable DALY-with a specific focus on air pollution and environmental/occupational risks. Finally, a Bayesian age-period-cohort (BAPC) model was applied to project future burden trends from 2022 to 2050. RESULTS: In 2021, the global number of asthma cases in this population was approximately 133 million, representing an 11.1% decrease compared to 1990 levels. The age-standardized incidence rate (ASIR) declined from 4,487.86 per 100,000 population in 1990 to 3,124.79 per 100,000 in 2021, with an EAPC of -1.04% (95% confidence interval [CI]: -1.196 to -0.891). High SDI regions had the highest prevalence rate (6,980.77 per 100,000), while low-middle SDI regions had the lowest (2,230.33 per 100,000). Both prevalence and incidence peaked in the 5-9 years age group. Males had higher asthma prevalence than females before age 15 years, with this pattern reversing thereafter. Key risk factors (by population attributable fraction [PAF]) included: for children, air pollution and environmental/occupational risks (3.5%); for young adults, environmental/occupational risks (13.9%) and high body-mass index (15.9%). Decomposition analyses indicated that population growth was the predominant driver of changes in asthma burden from 1990 to 2021 across SDI regions. The BAPC model predicted that the ASPR of asthma among children and young people globally would continue to increase, rising from approximately 4,132 per 100,000 population in 2021 to approximately 4,698 per 100,000 in 2050. CONCLUSIONS: Asthma burden in ages 5-39 years