BARCELONA, Spain — “Global warming” is synonymous with rising temperatures, but climate change is also causing extreme cold in certain areas. Now, a new analysis encompassing close to 2.3 million Europeans reports a series of troubling, detrimental associations between cold weather and heart disease-related deaths. Even worse, this connection is most prominent in poor neighborhoods.
Of course, studies have linked excessively hot weather to excess deaths from heart disease and stroke in patients with heart conditions. All in all, climate change represents a threat to human health and wellbeing on both ends of the thermometer.
“Climate change is leading to a rise in the average global temperature but also extreme cold in some regions. More than 70,000 excess deaths occurred across Europe during the summer of 2003 due to intense heatwaves. Cold weather also accounts for excess deaths and hospital admissions. Previously studies on the cardiovascular effects of heat and cold mainly used aggregated data, such as daily deaths in a city. The EXHAUSTION project used individual data, enabling us to identify vulnerable subgroups for protective interventions, thereby increasing resilience for future weather events,” says study author Professor Stefan Agewall from the University of Oslo in a media release.
This project included 2.28 million adults taken from five distinct studies conducted in numerous countries (Italy, Germany, Norway, Sweden, the United Kingdom) between 1994 and 2010. Average participant age ranged between 49.7 and 71.7 years-old, with the female proportion varying from 36 percent to 54.5 percent. The review included adults both with and without cardiovascular disease at baseline. Then, researchers recorded mortality and new-onset disease developments using death and disease registries, as well as follow-up heath surveys.
Cold temps may lead to new heart disease cases
To ascertain the daily average temperature at each participant’s home address, study authors looked to information provided by local weather stations or estimated weather conditions via models created by temperature data provided by weather stations.
Next, researchers analyzed the relationships connecting temperature, cardiovascular health, and death for all participants as a whole, and among subgroups according to particular characteristics. From there, they used study authors compared the temperature on the day of the week an adverse heart event occurred with the temperature on the same day of the week without an adverse event over the course of the same month for each participant. This approach helped researchers rid themselves of any potential confounding effects tied to participant characteristics and time trends.
Ultimately, the investigation revealed an association between cold weather and an increased risk of death due to both general cardiovascular disease and ischemic heart disease in particular, in addition to a higher risk of new-onset ischemic heart disease. If temperatures dropped by 10°C (50°F) from 41°F to 23°F, there was a 19-percent higher risk of death from cardiovascular disease and a 22-percent higher likelihood of death due to ischemic heart disease. Also, a four-percent higher risk of new-onset ischemic heart disease was associated with an approximately 11°C (51.8°F) temperature decline, from 35.6°F to 15.8°F.
“The relationships between cold temperatures and deaths were more pronounced in men and people living in neighborhoods with a low socioeconomic status. The links between cold and new-onset ischemic heart disease were stronger among women and people older than 65 years,” Prof. Agewall comments.
Heat makes heart disease worse
Regarding warm weather, heat was not found to be related to detrimental effects in the overall study population. However, increases in temperature from 15°C to 24°C (59°F to 75.2°F) were associated with 25-percent and 30-percent higher risks of death from cardiovascular disease and stroke, respectively, among participants with heart disease at baseline.
“Clinicians can use this information to provide tailored advice to those most at risk of adverse health outcomes during hot and cold days. Patients with heart conditions should stay hydrated in hot weather and adhere to advice from their cardiologist on medication use. We can all check the news for extreme heat and cold alerts and follow safety tips from local authorities,” Prof. Agewall concludes.
The team presented their findings at ESC Congress 2022.