Stroke hospital admissions and death rates may be linked to the weather, according to new research.
The findings, presented at the American Stroke Association's International Conference, suggest that more people are likely to have a stroke, and die from it, where there are big changes in air temperatures and higher humidity.
Dr Madina Kara, neuroscientist at the Stroke Association, said: “This research suggests that low temperatures increase peoples’ risk of stroke, and can lead to more patients dying after a stroke. Previous studies have indicated that that colder temperatures can be linked to increased blood pressure, especially in older people. High blood pressure is the biggest risk factor for stroke and it is essential that people have regular checks to make sure their blood pressure is under control.
“Although we still don’t fully understand why blood pressure rises during the winter, it is believed that cold weather can cause arteries to constrict and the blood to thicken, meaning that the blood has to be pumped harder in order to travel around the body. In the cold weather the Stroke Association recommends that people should take extra precautions to stay warm and reduce their risk of stroke.”
The team identified a nationwide sample of 134,510 people admitted to hospitals in 2009-10 for ischemic stroke, the most common type which is caused by a blood clot that blocks blood flow in or leading to the brain.
They compared the information with data on the weather including temperature and dew point - indicating higher air moisture and humidity - at the time.
The researchers found larger daily temperature changes and higher average humidity were associated with higher stroke hospitalisation rates. Lower average annual temperatures were linked with stroke hospitalisations and death, said the study.
With each 1°F increase in average temperature, there was approximately a one per cent drop in the odds of stroke hospitalisation and dying in the hospital after stroke. Increases in daily temperature fluctuation and average dew point pushed up the risk of going to hospital with a stroke, but not of dying in the hospital.