"The most important thing about hypertension is its controllability," O'Donnell said. "Blood pressure is easily measured, and there are lots of treatments."
Lifestyle measures to control blood pressure include reduction of salt intake and increasing physical activity, he said.
He added that the other risk factors -- smoking, abdominal obesity, diet and physical activity -- in the top five contributors to stroke risk were modifiable as well.
High intake of fish and fruits, for example, were associated with a lower risk of stroke, according to the study.
The researchers pointed out several potential limitations of the study, including the sample size, which they said "might be inadequate to provide reliable information" about the importance of each risk factor in different regions and ethnic groups.
Many of the same risk factors have cropped up in other studies, but this is the first stroke risk study to include both low- and middle-income participants in developing countries and to include a brain scan of all participating stroke survivors, according to the researchers.
The countries joining in the study were Argentina, Australia, Brazil, Canada, Chile, China, Colombia, Croatia, Denmark, Ecuador, Germany, India, Iran, Malaysia, Mozambique, Nigeria, Peru, Philippines, Poland, South Africa, Sudan and Uganda.
The INTERSTROKE study confirms that high blood pressure "is the leading cause of stroke in developing countries" as well as developed nations, Dr. Jack V. Tu, of the University of Toronto, wrote in an accompanying editorial. He added that it highlighted the need for health authorities in those countries to develop strategies to reduce high blood pressure, salt intake and other risk factors.
A second phase of the INTERSTROKE study is underway, with researchers looking at the importance of risk factors in different regions, ethnic groups and ty
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