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Heatwave warnings mitigate long-term cardiovascular diseases risk from heat-related illness: a real-world prospective cohort study

Qi Huang, Li-Mei Ke, Lin-Feng Liu, Yu-Yang Liu, Yan-Jun Li, Guo-Qing Feng, Bo Yin, Wen-Xin Xiang et al.

The Lancet Regional Health - Western Pacific, 2025

9,658,745 participants · 14 citations

Abstract

Summary Background Global warming is intensifying, exacerbating associated health issues. Heat-related illness, a critical risk during heatwaves, significantly impacts public health, yet its long-term health effects remain poorly understood. We established a cohort to investigate these health impact and explore the mitigative role of heatwave warnings. Methods Our cohort study enrolled 9,658,745 participants free of cardiovascular disease (CVD) at baseline from 1332 hospitals and 922 primary care centres in Shenzhen, China. The cohort was observed and followed up from January 1, 2017, to July 31, 2023. We utilized Cox proportional hazards model to analyse CVD incidence among participants who had heat-related illness versus those who did not, and further assessed causal relationship using instrumental variable approach. We employed stratified logistic regression to explore the protective effects of heatwave warning policies. Findings Among 9,658,745 participants followed up to 6 years, 238,278 (2.47%) developed CVD. People who developed CVD were generally older, male, with a higher degree of education, and with more hospital admissions before baseline. Heat-related illness was associated with CVD, with a hazard ratio of CVD 2.526 (95% CI = 2.301–2.773) among patients with heat-related illness compared with those without heat-related illness, and instrumental variable approach analysis suggested causation. Issuing heatwave warnings reduced hospital admissions for heat-related…

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 9,658,745 participants or records.

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