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

BACKGROUND: Asthma, a common chronic respiratory disease worldwide, is strongly influenced by several attributable risk factors. OBJECTIVE: To systematically examine global asthma burden trends attributable to major risk factors from 1990 to 2021 and forecast changes to 2050. METHODS: 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). RESULTS: 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%). CONCLUSION: 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.