Risk Factors for Stroke: A Global Study

Studies of modifiable risk factors for stroke have been conducted largely in developed countries. Few data have been collected in the developing world, where 85% of stroke mortality occurs… 

Replicating in part the methodology of the 2004 INTERHEART study of risk factors for first myocardial infarction (JW Gen Med Oct 5 2004), researchers recruited 3,000 patients with recent first strokes in 22 countries on 6 continents; both developing and developed countries were represented. Each case patient was matched by age and sex with a control patient from the same community who did not have a history of stroke. Virtually all case patients received neuroimaging to determine stroke type (78% ischemic; 22% hemorrhagic). 

As in the INTERHEART study, a small set of modifiable risk factors was identified. In this case, nine factors — hypertension, smoking, low waist-to-hip ratio, unhealthy diet, lack of regular exercise, diabetes, moderate or high alcohol intake, stress or depression, and high ratio of apoB to apoA1 lipoprotein — accounted for 90% of the worldwide risk for stroke. Contributions of various risk factors were similar across geographic regions. Hypertension alone accounted for 52% of risk for any stroke and 74% of risk for hemorrhagic stroke. Unlike waist-to-hip ratio, body-mass index was not associated with stroke risk.

Like a first myocardial infarction, a first stroke is largely preventable. In the developing world, hypertension, which can be evaluated and treated inexpensively, should be a particular target for intervention.

O’Donnell MJ et al. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the INTERSTROKE study): A case-control study. Lancet 2010 Jul 10; 376:112.