10 risk factors may be responsible for 90 percent of strokes worldwide

June 22, 2010

INTERSTROKE investigators led by Dr. Martin J. O’Donnell of McMaster University and colleagues estimate that 10 risk factors are collectively responsible for 90 percent of all strokes. The INTERSTROKE study follows the INTERHEART study. The previous study determined that 9 modifiable risk factors were responsible for the majority of heart attacks worldwide. “The INTERSTROKE study is the first large standardized case-control study of risk factors for stroke in which countries of low and middle income were included, and where all cases completed a brain scan (usually a CT scan),” the authors announce.

In phase I of the current study, 3,000 patients with a first stroke were compared with 3000 controls from 22 countries in order to establish traditional and emerging risk factors for stroke among nations of varying income. The INTERSTROKE investigators identified the following risk factors as accounting for 90 percent of the population attributable risk for stroke: high blood pressure, smoking, waist to hip ratio (abdominal obesity), diet, physical activity, lipids, diabetes, alcohol intake, stress and depression, and heart disorders including atrial fibrillation. When stroke was evaluated according to type, all risk factors were related to ischemic stroke, and hypertension, smoking, waist to hip ratio, diet, and alcohol were significant for hemorrhagic stroke, caused by bleeding in the brain. When the risk factors were examined independently, high blood pressure was found to be the most important. The study is published online on June 18, 2010 in the British medical journal The Lancet.