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Stroke can often be avoided, claims study

Ten modifiable risk factors account for 90% of strokes

Adrian O'Dowd

Monday, 18 July 2016

Many strokes could be avoided if people took steps to address and modify 10 lifestyle risk factors, concludes a large study1 published today in The Lancet, which involved an analysis of nearly 27,000 people from every continent in the world.

The global study was led by Dr Martin O’Donnell and Professor Salim Yusuf, both of McMaster University, Ontario, Canada and the HRB-Clinical Research Facility, NUI (National University of Ireland) Galway, along with collaborators from 32 countries.

It builds on preliminary findings2 from the first phase of the INTERSTROKE study, which identified 10 modifiable risk factors for stroke in 6,000 participants from 22 countries.

This full-scale INTERSTROKE study included an additional 20,000 individuals from 32 countries in Europe (including the UK), Asia, America, Africa and Australia, and sought to identify the main causes of stroke in diverse populations and within subtypes of stroke.

Stroke is still a leading cause of death and disability, particularly in low-income and middle-income countries and the two main types of stroke are ischaemic stroke which accounts for 85% of strokes and haemorrhagic stroke which accounts for 15% of strokes.

The researchers calculated the population attributable risk for each factor (PAR, meaning an estimate of the overall disease burden that could be reduced if an individual risk factor were eliminated) in order to estimate the proportion of strokes caused by specific risk factors.

They found that hypertension remains the single most important modifiable risk factor for stroke.

The PARs were:

  • 47.9% for hypertension
  • 35.8% for physical inactivity
  • 23.2% for poor diet
  • 18.6% for obesity
  • 12.4% for smoking
  • 9.1% for cardiac causes
  • 3.9% for diabetes
  • 5.8% for alcohol intake
  • 5.8% for stress
  • 26.8% for lipids

When combined together, the total PAR for all 10 risk factors was 90.7%, which was similar in all regions, age groups and in men and women.

However, the relative role of some individual risk factors varied by region, which the authors said should influence the development of strategies for reducing stroke risk.

Professor Yusuf said: “INTERSTROKE demonstrates that the majority of stroke is due to common modifiable risk factors.

“Our findings will inform the development of global population-level interventions to reduce stroke, and how such programmes may be tailored to individual regions, as we did observe some regional differences in the importance of some risk factors by region.

“This includes better health education, more affordable healthy food, avoidance of tobacco and more affordable medication for hypertension and dyslipidaemia.”

Writing in a linked comment,3 Professor Valery Feigin and Dr Rita Krishnamurthi from the National Institute for Stroke and Applied Neurosciences at University of Technology, Auckland, New Zealand, said the study provided various key messages.

“First, stroke is a highly preventable disease globally, irrespective of age and sex,” they said.

“Second, the relative importance of modifiable risk factors and their PAR necessitates the development of regional or ethnic-specific primary prevention programmes, including priority settings such as focusing on risk factors contributing most to the risk of stroke in a particular region (as determined by PAR).”

1. O'Donnell MJ, et al. Global and regional effects of potentially modifiable risk factors associated with acute stroke in 32 countries (INTERSTROKE): a case-control study. The Lancet, published online: 15 July 2016. DOI: 10.1016/S0140-6736(16)30506-2

2. O'Donnell MJ, et al. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the INTERSTROKE study): a case-control study. The Lancet, published online: 18 June 2010. DOI: 10.1016/S0140-6736(10)60834-3

3. Feiginemail VL, Krishnamurthi R. Stroke is largely preventable across the globe: where to next? The Lancet, published online: 15 July 2016. DOI: 10.1016/S0140-6736(16)30679-1

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