Global Asthma Burden due to Attributable Risk Factors, 1990-2021, and Forecast to 2050: A Systematic Analysis of the Global Burden of Disease Study 2021

Asthma, a common chronic respiratory disease worldwide, is strongly influenced by several attributable risk factors. To systematically examine global asthma burden trends attributable to major risk factors from 1990 to 2021 and forecast changes to 2050. Using 2021 GBD data, we estimated global asthma DALYs and age-standardized DALY rates (ASDRs) attributable to high BMI, smoking, occupational exposure, and NO₂ pollution, and explored their relationships with the Socio-demographic Index (SDI). Bayesian age-period-cohort (BAPC) modeling was used for forecasting, with 1990-2010 data serving as the training set for backtesting trends from 2011 to 2021, and with prediction accuracy evaluated with the mean absolute percentage error (MAPE). During 1990-2021, asthma burden related to most risk factors declined globally and across SDI quintiles. Backtesting confirmed BAPC model reliability (MAPE: high BMI 5.44%, smoking 1.16%, occupational asthmagens 3.35%). Worldwide, smoking-related burden declined most sharply: ASDR fell from 41.95 in 1990 to 16.19 in 2021 per 100,000 (-61.41%, estimated annual percentage change [EAPC] = -3.13). NO₂ pollution and occupational asthma burdens dropped 48.45% and 45.57%, respectively. High BMI showed the smallest reduction (-21.99%, EAPC = -0.85) and showed an increase in low-middle SDI regions (EAPC = 0.25). ASDRs for high BMI (ρ = -0.27), occupational risks, and smoking correlated negatively with SDI; NO₂ ASDR showed a significant positive correlation with SDI (ρ = 0.56, P < 0.001). By 2050, high BMI is projected to be the only risk factor with a continuously rising burden, with its ASDR rising from 39.42 in 2021 to 53.79 per 100,000 ( + 36.45%). Despite declines in asthma burden from all four factors, high BMI poses a growing threat with significant regional disparities. Future strategies should be tailored by SDI region and high-risk population, prioritizing surveillance and intervention for high BMI to counter its rising disease risk.