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Author Notes:

Barrak Alahmad, MD, MPH, PhD, Department of Environmental Health, Harvard T.H. Chan School of Public Health, 401 Park Dr, Landmark Center Room 412J, Boston, MA 02115. Email: b.alahmad@g.harvard.edu

B.Alahmad, A.Z., and AG set up the collaborative network. B.Alahmad and H. Khraishah conceptualized the idea. B.Alahmad, A.V.C., and A.G. designed the study. B.Alahmad, J.S., D.R., A.V.C., and A.G. developed the statistical methods. B.Alahmad and H.Khraishah drafted the manuscript and interpreted the results. A.Z., A.V.C., D.R., Y.G., S.I.P., S.A., F.A., B.Armstrong, M.B., B.Y.C., T.N.D., D.V.D., A.E., Y.L.L.G., M.H., Y.H., E.I., C.I., J.J.K., J.S., H.Kim, E.L., W.L., S.L., J.M., F.M., H.O., A.O., M.S.R., N.R., P.H.S., N.S., X.S., F.S., S.P.S., F.D., M.S., and A.T. provided the data, and contributed to the interpretation of the results and reviewed the manuscript. P.K., J.S., A.S.B., E.G., and A.G. supervised the research project and contributed to the interpretation of the results. B.Alahmad and F.S. accessed and verified the data. All authors had the final responsibility for the decision to submit for publication.

Disclosures: None


Research Funding:

This study was supported by the Kuwait Foundation for the Advancement of Science (CB21-63BO-01); the US Environmental Protection Agency (RD-835872); Harvard Chan National Institute of Environmental Health Sciences Center for Environmental Health (P01ES009825); the UK Medical Research Council (MR/R013349/1); the UK Natural Environment Research Council (NE/R009384/1); the European Union’s Horizon 2020 Project Exhaustion (820655); the Australian National Health and Medical Research Council (APP 2000581, APP 1109193, APP 1163693); the National Institute of Environmental Health Sciences–funded HERCULES Center (P30ES019776); the MCIN/AEI/10.13039/501100011033 (grant CEX2018-000794-S); the Taiwanese Ministry of Science and Technology (MOST 109–2621-M-002–021); the Environmental Restoration and Conservation Agency, Environment Research and Technology Development Fund (JPMEERF15S11412); the São Paulo Research Foundation; and Fundação para a Ciência e a Tecnlogia (SFRH/BPD/115112/2016). The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. The contents are solely the responsibility of the grantees and do not necessarily represent the official views of the funding agencies. Furthermore, the funding agencies do not endorse the purchase of any commercial products or services related to this publication.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Cardiac & Cardiovascular Systems
  • Peripheral Vascular Disease
  • Cardiovascular System & Cardiology
  • climate change
  • cold temperature
  • heart failure
  • heat
  • hot temperature
  • myocardial ischemia
  • stroke
  • HEAT

Associations Between Extreme Temperatures and Cardiovascular Cause-Specific Mortality: Results From 27 Countries

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Journal Title:



Volume 147, Number 1


, Pages 35-46

Type of Work:

Article | Final Publisher PDF


Background: Cardiovascular disease is the leading cause of death worldwide. Existing studies on the association between temperatures and cardiovascular deaths have been limited in geographic zones and have generally considered associations with total cardiovascular deaths rather than cause-specific cardiovascular deaths. Methods: We used unified data collection protocols within the Multi-Country Multi-City Collaborative Network to assemble a database of daily counts of specific cardiovascular causes of death from 567 cities in 27 countries across 5 continents in overlapping periods ranging from 1979 to 2019. City-specific daily ambient temperatures were obtained from weather stations and climate reanalysis models. To investigate cardiovascular mortality associations with extreme hot and cold temperatures, we fit case-crossover models in each city and then used a mixed-effects meta-analytic framework to pool individual city estimates. Extreme temperature percentiles were compared with the minimum mortality temperature in each location. Excess deaths were calculated for a range of extreme temperature days. Results: The analyses included deaths from any cardiovascular cause (32 154 935), ischemic heart disease (11 745 880), stroke (9 351 312), heart failure (3 673 723), and arrhythmia (670 859). At extreme temperature percentiles, heat (99th percentile) and cold (1st percentile) were associated with higher risk of dying from any cardiovascular cause, ischemic heart disease, stroke, and heart failure as compared to the minimum mortality temperature, which is the temperature associated with least mortality. Across a range of extreme temperatures, hot days (above 97.5th percentile) and cold days (below 2.5th percentile) accounted for 2.2 (95% empirical CI [eCI], 2.1-2.3) and 9.1 (95% eCI, 8.9-9.2) excess deaths for every 1000 cardiovascular deaths, respectively. Heart failure was associated with the highest excess deaths proportion from extreme hot and cold days with 2.6 (95% eCI, 2.4-2.8) and 12.8 (95% eCI, 12.2-13.1) for every 1000 heart failure deaths, respectively. Conclusions: Across a large, multinational sample, exposure to extreme hot and cold temperatures was associated with a greater risk of mortality from multiple common cardiovascular conditions. The intersections between extreme temperatures and cardiovascular health need to be thoroughly characterized in the present day - and especially under a changing climate.

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© 2022 The Authors.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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