The number of strokes would be almost halved if high blood pressure was eliminated and would be cut by 36 per cent if people were physically active, according to new research.
Ten risk factors, all of which can be modified, are responsible for nine of 10 strokes worldwide, but the ranking of the factors varies regionally, says the study in the medical journal The Lancet.
It was led by researchers from NUI Galway and McMaster University, Canada.
The latest phase of the Interstroke study, which began in 2007, builds on findings that identified the 10 modifiable risk factors for stroke in 6,000 participants from 22 countries.
This full-scale study added 20,000 individuals from 32 countries in Europe, Asia, America, Africa and Australia, and sought to identify the main causes of stroke in diverse populations, young and old, men and women and within subtypes of stroke.
Stroke is a leading cause of death and disability, particularly in low-income and middle-income countries.
Ischaemic stroke caused by blood clots accounts for 85 per cent of strokes and haemorrhagic stroke or bleeding into the brain accounts for 15 per cent.
The investigators found the number of strokes would be cut almost in half (48 per cent) if hypertension was eliminated; by more than a third (36 per cent) if people were physically active; and by almost one fifth (19 per cent) if they had better diets.
In addition, the proportion of strokes would be cut by 12 per cent if smoking was eliminated; by 9 per cent for cardiac causes, 4 per cent for diabetes, 6 per cent for alcohol intake, 6 per cent for stress, and by 27 per cent for lipids.
Risk factors
Many of the risk factors are known to also be associated with each other.
The researchers said the importance of some risk factors appeared to vary by region but when all 10 were included together, their collective importance was similar in all regions.
The study was led by Dr Martin O’Donnell of HRB-Clinical Research Facility, NUI Galway and Dr Salim Yusuf of the Population Health Research Institute at McMaster University.
Dr O’Donnell, a stroke physician with the Saolta University Healthcare Group, said the study had the size and scope to explore stroke risk factors in all major regions of the world and within key populations.
“We have confirmed that 10 modifiable risk factors are associated with 90 per cent of stroke risk in all parts of the world, in both men and women, and in younger and older people.
“The study also confirms that hypertension is the most important modifiable risk factor in all regions, and the key target in reducing the burden of stroke globally.”
About 10,000 strokes happen in Ireland each year, according to the Irish Heart Foundation. Five out of six happen in people over the age of 60. About a fifth of those hospitalised with a stroke will die in hospital. Most of the remaining number require some level of rehabilitation.
Forty four participants in the study were from Ireland.