Climate change predicted to spike cardiovascular deaths in China

By Dr. Liji Thomas, MDApr 21 2024Reviewed by Benedette Cuffari, M.Sc.

A new study published in the journal eBioMedicine aims to predict the extent to which climate change may impact the risk of cardiovascular disease (CVD) mortality in China.

Study: Projecting heat-related cardiovascular mortality burden attributable to human-induced climate change in China. Image Credit: Piyaset / Shutterstock.com

Climate change and CVD

Current estimates indicate that about 19 million people die each year due to CVD, five million of whom reside in China. Furthermore, CVD causes over 390 million disability-adjusted life years (DALYs) globally.

Due to climate change, the global temperature at the earth's surface has risen by 1.15 °C above that in the pre-industrial era. Previous studies have reported an adverse impact of climate change on overall mortality that is dependent on age, sex, and cause of death, as well as deaths due to CVD.

Heat affects the cardiovascular system in multiple ways, including the excretion of salt and water as sweat, higher cholesterol levels, and hemodynamic strain. Moreover, climate change-related heat can increase the risk of atherosclerotic thrombosis of the heart and brain vessels and, as a result, the rate of strokes and heart attacks.

About the study

The present study attempted to predict CVD mortality associated with climate change in a Chinese setting. Current temperatures were measured at 161 disease surveillance points (DSPs).

These projections were based on the Coupled Model Intercomparison Project Phase 6 (CMIP6), which is under the World Climate Research Programme (WCRP). WCRP examines natural climate change and the combined scenario with both natural and anthropogenic impacts on the climate.

A total of 22 General Climate Models (GCMs) were used to determine projected temperatures from 2010 to 2100 in both human-induced and natural scenarios. Human-induced scenarios were calculated based on the difference between the combined and natural impacts.

Recognizing that economic and social change is closely related to climate change, the Intergovernmental Panel on Climate Change (IPCC) has presented a series of integrated scenarios that combine both shared socioeconomic pathways (SSPs) and climate representative concentration pathways (RCPs).

Study findings

The mean annual temperature at the DSPs varied from 12.6 to 28.4 °C, during which time about 330,000 CVD deaths occurred.

Under natural conditions, the summer temperatures in China would not significantly change. Similarly, in this scenario, the proportion of CVD deaths related to heat would decline by 0.5% in the 2090s as compared to 2010 death rates due to CVD.

Conversely, summer temperatures increased by 5-6 °C with the combined scenarios, depending on the region. The predicted CVD mortality fraction in the 2090s rose from 10% to 30%, depending on the modeled scenario.

The death rate among CVD patients followed a J-shaped curve beyond a critical minimum temperature. The most significant increase relative to baseline temperature was in the South and East of China.

The proportion of heat-related deaths due to CVD with human-induced climate change continued to rise during each decade from about 31% in the 2010s to an estimated 70-90% in the 2090s under different scenarios.

Individuals who were considered to be most vulnerable to heat-related CVD mortality included those living in rural areas, those with lower education levels, stroke patients, females, older adults, and those residing in Southern and Eastern China. Importantly, individuals with lower levels of education are more likely to work outdoor jobs, have unequal access to healthcare, and be diagnosed with chronic diseases.

Conclusions

"This study provides evidence that human activities will amplify future heat-related cardiovascular mortality burden.”

Anthropogenic climate change resulting in CVD deaths could account for as much as 90% of excess mortality due to excessive heat by 2090. Simultaneously, the CVD burden associated with natural climate change may not change significantly. Nevertheless, the study findings emphasize the importance of limiting carbon emissions to prevent further global warming ultimately.

"Active adaptation and mitigation measures towards future warming could yield substantial health benefits for the patients with CVD.”

Future studies are needed to identify populations and groups at the greatest risk of climate-related health effects and the different types of risk that may be associated with global climate change. These data will assist in implementing integrated and sensitive public health policies to ultimately reach environmental targets.