Assessing the Impact of Extreme Climate Events on Cardiovascular Disease in 157 Chinese Cities (2015-2020): A Spatial...

Extreme climate events worsen cardiovascular disease burden, exacerbated by rapid aging. Prior studies have linked extreme climate events to cardiovascular disease mortality but have lacked city-level spatial extreme climate event impact data and causal evidence for extreme climate event-related cardiovascular diseases in individuals. This study explored the spatiotemporal patterns of 3 extreme climate event types (heat, cold, and precipitation) in 157 Chinese cities (2015-2020) and verified their causal effects on individual incident cardiovascular disease risk.

A repeated cross-sectional (spatial analysis) and longitudinal cohort (causal inference) mixed design was used. Extreme climate events were defined using 2 thresholds: absolute (heat ≥38°C, cold ≤ -10°C, and extreme precipitation >50 mm) and relative. Subsequent analyses and results were based on the absolute threshold, which provided a better model fit. Spatial autocorrelation was used to identify cardiovascular disease clusters, multiscale geographically and temporally weighted regression was used to quantify extreme climate event city-level cardiovascular disease associations, and dynamic double machine learning was used to examine individual causality/heterogeneity.

Northeast China's cities were found to be sites of increased cardiovascular disease incidence. Heat extreme climate events increased city-level cardiovascular disease prevalence (east-west weakening impact). Each additional heat extreme climate event day was correlated with 1,128 more cardiovascular disease cases per 100,000 people. Cold extreme climate events increased city-level cardiovascular disease prevalence (west-east weakening impact). Each additional cold extreme climate event day was correlated with 391 more cardiovascular disease cases per 100,000 people. Causal inference analysis showed that each heat extreme climate event day increased cardiovascular disease risk by 3.044%; cold extreme climate event days increased risk by 0.110%, and precipitation extreme climate event days increased it by 1.620%. Heterogeneity highlighted high-risk subgroups in which heat extreme climate events affected preretirees, smokers, and those in high-ozone areas, whereas higher BMI values mitigated risk. Cold extreme climate events impacted preretirees, high-BMI individuals, and high-ozone populations. Precipitation extreme climate events most affected older adults, rural residents, preretirees, and spouseless individuals.

Heat and cold extreme climate events increased city-level cardiovascular disease prevalence in middle-aged and older adults with distinct spatiotemporal gradients. Exposure to heat, cold, and precipitation extreme climate events significantly increased incident cardiovascular disease risk, with clear subgroup vulnerabilities.