The rate of strokes suffered by Australians has dropped over the past 20 years, while strokes caused by an irregular heartbeat now account for one third of all strokes, according to new research led by the University of Adelaide.
The results of a major stroke incidence study are published in this month's issue of the international journal Stroke. The study looked at the number and causes of strokes among 148,000 people living in the western suburbs of Adelaide.
The study, conducted in 2009-2010, found that the incidence of first stroke was 161 per 100,000 people per annum. That's down by almost 10% on a similar population study in Perth in 1989-1990, which found the incidence of first stroke was 178 per 100,000 people.
"With an increasingly aging population, we might have expected to see the number of strokes in the community rising. However, what we're seeing is that the rate of strokes is actually decreasing, which is good news for Australians," says a chief investigator of the study, Professor Jonathan Newbury from the University of Adelaide's School of Population Health.
"We attribute the decrease in the rate of stroke to two things: first, the public health message about the dangers of smoking is getting out there and we know the number of smokers has decreased; second, we now have much better management of blood pressure both at GP and specialist levels, and blood pressure drugs have improved.
"Smoking and high blood pressure can cause blood vessels to block or burst, which leads to stroke. As a community, we need to continue to manage these risk factors if we have any hope of seeing ongoing reductions in the rate of stroke," Professor Newbury says.
The study also highlighted the increasing role of the nation's most common heart rhythm disorder, atrial fibrillation (AF), in causing stroke. This irregular beating of the heart causes clots to form in the heart's atrium, which move and block blood circulation in the brain, causing stroke.
"Atrial fibrillation is now responsible for one third of all strokes in Australia - that's more than ever before," says the study's lead author, neurologist Dr James Leyden. Now based at the Lyell McEwin Hospital, Dr Leyden conducted the stroke incidence study for the University of Adelaide while working at the Queen Elizabeth Hospital in 2009-2010.
"These results demonstrate the need for people with irregular heartbeat to seek medical help as soon as they can, because many of these strokes can be prevented. It also shows the importance of ongoing research into atrial fibrillation, its causes, and improved treatments and cures," Dr Leyden says.
Professor Newbury says: "This new study reinforces the value of population-based studies to better understand the health needs of the community."
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