The epidemiology of asthma and its attributable risk factors from 1990 to 2021: A systematic analysis based on the Global Burden of Disease Study 2021 and Mendelian Randomization Studies

Objectives

Asthma is a commonly occurring condition due to chronic inflammation of the lower respiratory tract. This study aims to assess the global burden of asthma from 1990 to 2021 and the mortality trends caused by specific risk factors.

Study design

Systematic analysis based on the Global Burden of Disease Study 2021 and Mendelian Randomization studies.

Methods

Based on a global asthma scale spanning from 1990 to 2021, we performed a secondary analysis to explore the incidence, mortality, and disability-adjusted life-years (DALYs), along with risk factors for asthma. Mendelian randomization (MR) analyses were performed to verify the results.

Results

In 2021, there were 41,555,628 incident cases of asthma worldwide. Cases of asthma decreased by 0.09 % (95 % uncertainty interval [UI]: 0.12,0.06) from 1990 to 2021. Over the past three decades, asthma-associated deaths increased from 374,377 (95 % UI: 304,600–492,653) to 436,192 (95 % UI: 357,795–555,604). The global incidence rate decreased from 736.99 (95 % UI: 615.03–905.18) to 516.70 (95 % UI: 425.36–646.13) per 100,000 population; the asthma-associated mortality rate decreased from 9.64 (95 % UI: 7.76–12.80) to 5.20 (95 % UI: 4.27–6.59) per 100,000 population. Age-specific incidence and prevalence rates peaked in individuals under nine years old. The prevalence and incidence rates of asthma were relatively higher in individuals in countries with higher Socio-demographic Index (SDI); however, mortality and DALYs rates of individuals with asthma showed a reverse trend. Globally, occupational asthmagens, body mass index, smoking, and air pollution were key risk factors for asthma-associated mortality and DALYs in 2021. MR analyses further confirmed the strongly related correlation between body mass index, occupational asthmagens and asthma.

Conclusions

Although a mild decrease in total incidence cases of asthma was observed from 1990 to 2021, asthma has still continued to pose a life-threatening burden worldwide overall. Generally, asthma frequently occurred at younger ages and is more prevalent in high-SDI countries, indicating that specific periodic and regional features exist. Improved understanding of the epidemiology of asthma could facilitate future interventions to better manage the disease globally and support future investigation on the diagnosis and treatment of asthma.