Impact of non-optimal temperatures on ischemic heart disease: A comparative analysis between global SDI regions and China, 1990-2021

Background Non-optimal temperatures contribute substantially to ischemic heart disease (IHD) risk; however, comparative trends and determinants of the dual burdens associated with heat and cold exposure remain poorly understood, especially in China. This study compared the temperature-attributable burden of IHD in China with global and Socio-Demographic Index (SDI)-stratified patterns from 1990 to 2021 to identify major disparities. Methods Using data from the Global Burden of Disease 2021 study, we analyzed trends in temperature-attributable IHD trends via decomposition analysis, Joinpoint regression, and age-period-cohort modeling. Future trends through 2031 were projected using a Bayesian model. Results Globally, the age-standardized mortality rate (ASMR) attributable to non-optimal temperatures declined by 30.09%, primarily driven by reductions in the low-temperature burden. However, these improvements were largely confined to high-SDI regions, while lower-SDI regions experienced stagnant or worsening trends. In contrast, China demonstrated a 15.65% increase in overall ASMR, driven by a dual burden characterized by a marked rise in heat-related ASMR (+64.15%) and a concurrent increase in cold-related ASMR (+12.18%). Decomposition analysis identified fundamentally different driving forces between global and Chinese trends. Globally, epidemiological improvements exerted a strong protective effect (-256.56%), whereas in China, these factors contributed to an increase in per-capita risk (+169.82%). Projections to 2031 suggest these disparities are likely to persist. Conclusion China is facing a compounding IHD crisis driven by the combined impacts of both heat and cold exposure, representing a risk profile that differs fundamentally from global patterns. These findings highlight the urgent need for a paradigm shift toward tailored, dual-target public health strategies capable of simultaneously mitigating the adverse cardiovascular effects of both temperature extremes in vulnerable populations.