High blood pressure tops list of factors that can cause strokes

SMOKING, poor diet and an expanded waistline are included in a check-list of ten risk factors most closely associated with strokes, experts revealed yesterday.

Together, the list of harmful conditions and behaviours account for 90 per cent of stroke risk.

They were identified by researchers involved in the Interstroke study which looked at the lifestyle and biological factors that contribute to stroke in 22 countries.

The Canadian-led scientists analysed data from 3,000 patients who suffered their first stroke between March 2007 and April 2010.

Personal details were compared with those of a "control" population of 3,000 healthy individuals.

Five lifestyle-linked factors – high blood pressure, smoking, abdominal obesity, diet and physical activity – accounted for more than 80 per cent of the worldwide risk of stroke on their own.

Most of the risk factors mirrored those associated with heart attacks, previously highlighted in another study called Interheart.

The results were published online yesterday by the medical journal, the Lancet. Dr Martin O'Donnell, of McMaster University in Hamilton, Ontario, and colleagues wrote: "Our findings suggest that ten risk factors are associated with 90 per cent of the risk of stroke."

He said that targeted interventions that reduced blood pressure and smoking, and promoted physical activity and healthy diet, could substantially reduce the chances.

Of all the factors, high blood pressure was by far the most important, accounting for a third of all stroke risk.

People who had a history of high blood pressure were more than two and a half times more likely to suffer a stroke than those who did not.

Smoking was another major hazard, the study found, and associated with one in five strokes. Smokers had double the stroke risk of non-smokers.

Each year an estimated 150,000 people in the UK have either a full-blown or "mini" stroke for the first time. Around a third of these patients die, a third recover, and a third are left with a serious disability.

Writing in the Lancet, Dr Jack Tu, from the Institute for Clinical Evaluative Sciences at the University of Toronto, said: "Whilst hypertension (high blood pressure] is well established as the most important cause of stroke in high-income countries, Interstroke confirms that it is also the most important risk factor for stroke in developing countries.

"This finding is particularly relevant because it highlights the need for health authorities in these regions to develop strategies to screen the general population for high blood pressure, and, if necessary, offer affordable treatment.

"It also provides an impetus to develop population-wide strategies to reduce the salt content in the diet of individuals in these countries."

Phase II of Interstroke, now under way, aims to include 20,000 participants and will look at the importance of risk factors within different regions and ethnic groups. It will also study genetic links to the risk of stroke.

Andrea Lane, from the Stroke Association, said: "The study is interesting as it looks at the major risk factors for stroke worldwide."