Weather extremes, like excessively hot and cold days, have been linked to higher mortality rates for people with heart diseases.
Cardiovascular disease (CVCs), or heart disease, is the leading cause of death worldwide.
Researchers have found that people with heart disease have higher mortality rates in either hot or cold weather extremes.
The study, published in the American Heart Association journal Circulation, is the largest of its kind, finding data from more than 32 million people in 567 cities across 27 countries and five continents.
The study urges doctors and scientists to develop warning systems and guidelines for people who are more likely to die from heart disease during extreme temperatures.
A study in the American Heart Association’s (AHA) journal, Circulation, found that people with heart diseases like arrhythmia, heart failure, ischemic heart disease (heart problems caused by narrowed heart arteries), and stroke are more likely to die during weather extremes.
Even though there have been studies linking weather and heart disease before, their results were limited because they only looked at certain types of heart disease in certain locations.
Research is the first of its kind that was able to focus on a much wider scope of people. The study found information from more than 32 million people who died of heart disease between 1979 and 2019. These deaths occurred in 567 cities across 27 countries and five continents.
Researchers were able to look at health records based on data from the Multi-Country Multi-City (MCC) Collaborative Research Network. This global data includes vital perspectives from epidemiologists, biostatisticians, and climate scientists studying the health impacts of climate and related environmental stressors on death rates.
Since climate change can cause extreme swings in weather from severe cold to severely hot temperatures, researchers made sure to examine both in the study.
The study compared the number of cardiovascular deaths in each city on the days with the best temperature (the temperature linked to the fewest deaths) to the days with the hottest and coldest temperatures in the same city.
Dr. Haitham Khraishah, co-author of the study, explained, “One in every 100 cardiovascular deaths may be attributed to extreme temperature days, and temperature effects were more pronounced when looking at heart failure deaths.”
Here’s how weather extremes affect cardiovascular deaths, according to the American Heart Association newsroom:
For every 1,000 cardiovascular deaths, the researchers found that:
- Extreme hot days accounted for 2.2 additional deaths.
- Extreme cold days accounted for 9.1 additional deaths.
- Of the types of heart diseases, the greatest number of additional deaths was found for people with heart failure (2.6 additional deaths on extreme hot days and 12.8 on extreme cold days).
Cardiovascular disease (CVCs) is the leading cause of death worldwide. Heart attacks and strokes account for more than four out of every five CVD deaths, with one-third of these deaths occurring in people under the age of 70.
Researchers explained that these findings show that we may need to present warning systems and guidelines for people who are more likely to die from heart disease during extreme temperatures.
Researchers also note that because the study underrepresents data from South Asia, the Middle East and Africa, findings are limited in making global estimates about the impact of extreme temperatures on cardiovascular deaths.
However, co-authors of the study are hopeful to begin further studies to expand research connecting weather extremes and heart disease.
"This study contributes important information to the ongoing societal discussions regarding the relationship between climate and human health. More work is needed to better define these relationships in a world facing climate changes across the globe in the years ahead, especially as to how those environmental changes might impact the world’s leading cause of death and disability, heart disease,"AHA Past President, Dr. Robert A. Harrington