https://studyfinds.com/cold-snaps-line-up-with-cardiac-arrest-spikes-new-study-finds/
By StudyFinds Analysis – Reviewed by Patrisha Antonaros
Research led by Endre Zima (Semmelweis University)
– Published in the journal Public Health. Higher cardiac arrest counts were consistently associated with colder temperatures and lower wind speeds, and for every 1 degree Celsius the temperature dropped, daily cardiac arrests rose by 1.4%. –
On the days with the most cardiac arrests, counts ran nearly a third above normal, about 19 extra cases nationwide, and those days tended to be cold and calm.
Colder temperatures and lower wind speeds were consistently associated with higher cardiac arrest counts, with weather patterns extending across a window of up to three days.
Winter months saw almost 18% more cardiac arrests than summer months, a pattern confirmed by both traditional statistics and machine learning.
On the days when cardiac arrests outside hospitals ran highest, counts climbed nearly a third above a typical day, an extra 19 or so nationwide, and those days shared a common signature: cold, still air. That’s the central finding from a five-year study that tracked every out-of-hospital cardiac arrest recorded by Hungary’s national ambulance service, the kind of sudden, deadly event where a person’s heart stops and paramedics race against the clock to save them.
Researchers compared more than 114,000 cardiac arrest cases against daily weather data collected from late 2018 through the end of 2023, publishing their results in the journal Public Health. Higher cardiac arrest counts were consistently associated with colder temperatures and lower wind speeds, and for every 1 degree Celsius the temperature dropped, daily cardiac arrests rose by 1.4%.
This is not a story about one bad flu season or a single storm. It’s a pattern that repeated across five years, and it held up even when researchers checked their work a second, completely different way, using a separate machine-learning model to test which weather factors were most useful for predicting daily cardiac arrest counts. That second check pointed to the same factors, which is why researchers say weather forecasts could someday give emergency services an early warning, enough lead time to prepare before a surge hits.
How Scientists Tracked Cardiac Arrest Cases in Hungary
Hungary turned out to be a nearly ideal place to study this question. Its ambulance service is centralized, meaning every cardiac arrest case in the country gets logged in one system, with no gaps caused by patients using different hospital networks or private providers. That gave researchers a full national picture instead of a patchwork drawn from a few cities.
After setting aside part of 2020 to avoid mixing in the disruption of the early COVID-19 pandemic, when ambulance protocols and public behavior changed dramatically, scientists were left with 1,584 days of data covering 114,830 cardiac arrest cases. On an average day, close to 61 people suffered a cardiac arrest outside a hospital. Those affected were typically older adults, around 70 on average, and more often men than women.
Weather information came from Hungary’s national weather service and included temperature, wind speed, air pressure, humidity, and pollution levels, all measured as daily national averages. Preliminary checks found strong agreement among weather stations for daily temperature, suggesting the national averages reasonably represented conditions across a country that is not especially small.
