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Stroke is a major global health problem, yet few studies have examined the risk factors for stroke and its subtypes in different ethnic populations representing different regions of the world.  Compared to coronary heart disease, traditional risk factors (e.g. hypertension, hypercholesterolemia) appear to exert different magnitudes of risk for stroke and within stroke subtypes.  Any effective global strategy to reduce the risk of stroke mandates a systematic and standardised study of the contribution of traditional and emerging risk factors within defined ethnic groups and geographical locations for each of the stroke subtypes.  In order to provide reliable answers, these studies need to be very large, so as to include large numbers of cases of strokes of each subtype.


INTERSTROKE has been designed to achieve this by utilising a global research network of investigators centrally coordinated through the Public Health Research Institute in Hamilton, Ontario, Canada.  Many members of this research network completed a similar study in 2005 for myocardial infarction (MI) called INTERHEART. INTERHEART included 30,000 participants from 52 countries and showed that nine modifiable risk factors accounted for over 90 per cent of the risk.


A similar study is necessary in stroke because:

1.  the causes of stroke are far more diverse than MI;

2.  many of the common risk factors for stroke and MI (eg lipids) appear to exert very different magnitudes of risk for stroke compared with MI, and;

3.  there are limited epidemiological studies in stroke.


This study compares risk factors in people with stroke (cases) to people without stroke (controls) in a large, international case control study that includes approximately 24,000 cases and controls from about 37 countries. Countries will recruit the following ethnic groups: Caucasians, Chinese, South Asians, Africans and native South Americans.


The pilot phase of INTERSTROKE, conducted to demonstrate the feasibility of such a large study in stroke, has recently been completed with more than 2,800 participants recruited from 15 countries (Australia, Argentina, Brazil, Canada, Chile, China, Colombia, Denmark, Germany, Ghana, India, Mozambique, Poland, South Africa and Uganda).  Results from the Pilot Study will be presented at the European Stroke Conference in Barcelona in May 2010.


Now that the Pilot Phase has been completed there will be a transition into the main study with up to 10 centres participating in Australia. INTERSTROKE will provide essential information on conventional and emerging risk factors to help guide population health initiatives aimed at preventing stroke in low and high income countries. To be successful, INTERSTROKE will involve national and international collaboration. John Varigos, from CCRE Therapeutics, is the national coordinator and, together with Graeme Hankey from the Royal Perth Hospital, will coordinate the Australian arm of the study. INTERSTROKE will have enormous implications for our understanding of the causes of stroke within Australia and around the world.