Impact of extreme temperature on congenital heart disease mortality: a population-based nationwide case-crossover studyResearch in context

Abstract

Summary: Background: The association between congenital heart disease (CHD) and non-optimal temperatures has received limited investigation. We aimed to investigate the impact of extreme temperatures on CHD mortality. Methods: We reviewed the National Mortality Surveillance System of China and retrieved death records attributable to CHD from 2013 to 2021. Temperature and air pollutants data were obtained from the ERA5-Land reanalysis dataset and the ChinaHighAirPollutants database. A two-stage case-crossover study design was implemented. Sensitivity and subgroup analyses were performed to test the robustness of findings and determine the vulnerable population. Findings: A total of 32,168 CHD deaths were included, showing a significant association between cold and CHD mortality, while there was little effect for heat. The odd ratio (OR) ranged from 1.05 (95% confidence interval: 1.00–1.10) to 1.15 (1.03–1.29) across country, with a more pronounced impact in non-monsoon regions up to 1.67 (1.20–2.32). Cold extremes accounted for an attributable fraction of 4.09 per 1000 CHD death nationwide and 13.30 per 1000 CHD deaths in non-monsoon regions. Sensitivity analyses utilizing apparent temperature and adjusting for air pollutants confirmed the robustness of the main findings. Female and pediatric CHD patients were identified as the vulnerable population to cold extremes. Interpretation: For the first time, this nationwide study demonstrated the significant impact of cold extremes on CHD mortality, particularly in non-monsoon regions, and among female and pediatric subgroups. These findings may suggest that healthcare professionals advise CHD patients to avoid exposure to cold extremes, and provide insight into healthcare policy adjustment. Funding: This study was supported by the CAMS Innovation Fund for Medical Sciences (CIFMS, 2023-I2M-C&T-B-059), the Capital Health Research and Development of Special Fund (2022-1-4032) and the National High Level Hospital Research Funding (2022-GSP-GG-19).

Keywords

• Congenital heart disease
• Extreme temperature
• Mortality
• Cold extreme