Differentiating the impact of non-optimum temperature and temperature variability on cause-specific cerebrovascular mortality: An individual-level, case-crossover study in Shanghai, China

Xiaozhen Su; Yifeng Qian; Ying Liu; Lu Zhou; Yichen Guo; Su Shi; Renjie Chen; Hao Sun; Haijun Gui; Yuhao Zhang

doi:10.1016/j.ecoenv.2025.118339

Ecotoxicology and Environmental Safety (Jul 2025)

Differentiating the impact of non-optimum temperature and temperature variability on cause-specific cerebrovascular mortality: An individual-level, case-crossover study in Shanghai, China

Xiaozhen Su,
Yifeng Qian,
Ying Liu,
Lu Zhou,
Yichen Guo,
Su Shi,
Renjie Chen,
Hao Sun,
Haijun Gui,
Yuhao Zhang

Affiliations

Xiaozhen Su: Department of Environmental Health, School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China
Yifeng Qian: Department of Oral and Craniomaxillofacial Surgery, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology, China
Ying Liu: Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China; National Clinical Research Center for Interventional Medicine, Shanghai, China
Lu Zhou: Department of Environmental Health, School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China
Yichen Guo: Department of Environmental Health, School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China
Su Shi: Department of Environmental Health, School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China
Renjie Chen: Department of Environmental Health, School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China
Hao Sun: Department of Oral and Craniomaxillofacial Surgery, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology, China; Correspondence to: Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, 639 Manufacturing Bureau Road, Shanghai 200011, China.
Haijun Gui: Department of Oral and Craniomaxillofacial Surgery, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology, China; Correspondence to: Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, 639 Manufacturing Bureau Road, Shanghai 200011, China.
Yuhao Zhang: Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China; National Clinical Research Center for Interventional Medicine, Shanghai, China; Correspondence to: Department of Neurology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai 200032, China.

DOI: https://doi.org/10.1016/j.ecoenv.2025.118339
Journal volume & issue: Vol. 299
p. 118339

Abstract

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Background: Cerebrovascular mortality exhibits seasonal variation, but the roles of temperature and temperature variability (TV) in cause-specific cerebrovascular mortality remain unclear. Methods: This individual-level time-stratified case-crossover research collected individual cerebrovascular death records during 2005–2021 in Shanghai, China. TV was calculated as the standard deviation of daily minimum and maximum temperature over consecutive days. Conditional logistic regression models combined with distributed lag nonlinear models were utilized to evaluate the cumulative exposure-response associations. Results: Based on a total of 388,823 cerebrovascular deaths, we found that exposure to extreme cold, extreme heat, and greater TV was significantly related to increased cause-specific cerebrovascular mortality. Extreme cold exhibited the strongest impact on hemorrhagic stroke [relative risk (RR) = 1.84; 95 % confidence interval (CI): 1.50, 2.26], followed by hemorrhagic stroke sequelae [1.75 (95 % CI: 1.25, 2.45)] and cerebrovascular sequelae [1.71 (95 % CI: 1.58, 1.86)]. Extreme heat showed the largest effect on cerebrovascular sequelae [1.35 (95 % CI: 1.29, 1.41)], followed by ischemic stroke sequelae [1.34 (95 % CI: 1.28, 1.41)]. TV was associated with the largest percentage increase in ischemic stroke sequelae [2.12 % (95 % CI: 1.35 %, 2.90 %)], followed by cerebrovascular sequelae [1.95 % (95 % CI: 1.23 %, 2.68 %)]. Stratified analyses revealed stronger associations in the elders, singles, and those with low education. Conclusions: This case-crossover study provides the first-hand evidence that extreme temperatures and TV may elevate the risk of cause-specific cerebrovascular mortality, which underscore the urgency of implementing targeted protective measures for cerebrovascular patients facing extreme weather events, particularly among aging populations in megacities under climate change.

Published in Ecotoxicology and Environmental Safety

ISSN: 0147-6513 (Print); 1090-2414 (Online)
Publisher: Elsevier
Country of publisher: United States
LCC subjects: Technology: Environmental technology. Sanitary engineering: Environmental pollution; Geography. Anthropology. Recreation: Environmental sciences
Website: https://www.journals.elsevier.com/ecotoxicology-and-environmental-safety

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