Hypertension biggest preventable global risk factor for stroke

Hypertension is the most important modifiable risk factor for stroke, according to a new study led by a scientist of Indian origin which found that ninety per cent of the stroke cases around the world are preventable. Ten risk factors that can be modified are responsible for nine of 10 strokes worldwide, but the ranking of those factors vary regionally, according to the study.

Prevention of stroke is a major public health priority, but the variation by region should influence the development of strategies for reducing stroke risk, researchers said.

Stroke is a leading cause of death and disability, particularly in low-income and middle-income countries.

The two major types of stroke include ischaemic stroke caused by blood clots, which accounts for 85 per cent of strokes, and haemorrhagic stroke or bleeding into the brain, which accounts for 15 per cent of strokes. The study led by Martin O'Donnell and Salim Yusuf of the Population Health Research Institute (PHRI) of McMaster University in Canada and collaborators from 32 countries,

builds on findings from the first phase of the INTERSTROKE study which identified ten modifiable risk factors for stroke in 6,000 participants from 22 countries.

The 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.

"This study has the size and scope to explore stroke risk factors in all major regions of the world and within key populations," said O'Donnell.

"We have confirmed the ten modifiable risk factors associated with 90 per cent of stroke cases in all regions,

young and older and in men and women," he said.

"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," he added.

The study looked at the different risk factors, and determined the proportion of strokes which would be cut if the risk factor disappeared.

The number of strokes would be practically cut in half if hypertension was eliminated; trimmed by more than a third if people were physically active; and shaved by almost one fifth if they had better diets.

In addition, this proportion was cut back by 12 per cent if smoking was eliminated; 9 per cent for cardiac (heart) causes, 4 per cent for diabetes, 6 per cent for alcohol intake, 6 per cent for stress, and 27 per cent for lipids.

Many of these risk factors are known to also be associated with each other (such as obesity and diabetes), and when were combined together, the total for all 10 risk factors was 91 per cent, which was similar in all regions, age groups and in men and women.

Researchers said the key messages from the study were that stroke is a highly preventable disease globally, regardless of age and sex.

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