Autism spectrum disorder burden in China and worldwide, 1990-2021: A comparative ecological time-series study using global burden of disease 2021 data.

Autism spectrum disorder (ASD) imposes a substantial public health burden. This study quantified and compared the ASD burden in China and globally from 1990 to 2021 to inform policy and planning. We analyzed Global Burden of Disease 2021 estimates of age-standardized prevalence rates (ASPR) and age-standardized disability-adjusted life-year rates (ASDR) in China and worldwide, with analyses by sex and age. Joinpoint regression characterized historical trends. Autoregressive integrated moving average (ARIMA) models generated exploratory projections for 2022 to 2031; no temporal holdout validation or comparison with alternative forecasting approaches was performed. In 2021, ASPR per 100,000 population was 655.75 (95% uncertainty interval [UI] 545.06-780.37) in China and 788.34 (95% UI 663.76-927.21) globally; ASDR was 124.19 (95% UI 83.70-175.10) and 147.56 (95% UI 100.21-208.16), respectively. From 1990 to 2021, the average annual percent changes in ASPR and ASDR were 0.22% (95% confidence interval [CI] 0.21-0.24) and 0.23% (95% CI 0.21-0.25) in China, compared with 0.06% (95% CI 0.06-0.07) and 0.07% (95% CI 0.06-0.08) globally. The estimated burden was higher in males. The exploratory ARIMA point projections suggested a modest decline in ASPR in both settings and in global ASDR but an increase in China's ASDR. These directions have not been validated out of sample. Historical estimates indicate an increasing ASD burden in China and worldwide. The ARIMA results represent model-based scenarios, not validated future trajectories. The existing burden supports sustained attention to early identification, long-term care, and family support; resource planning should not rely on these projections alone.