The majority of studies on stroke have been conducted in westernized or developed countries. Yet, recent surveys show that the disease burden of stroke is concentrate in low- and middle income countries, where 85% of deaths due to stroke occur.
The INTERSTROKE study might be able to rectify this knowledge gap. The study looked at 3000 first time acute stroke cases from 22 countries and compared these with 3000 controls. In the study, low income and developing countries are well-represented, with only 14% of the participants coming from high-incomes countries whereas 81% come from Southeast Asia, India or Africa.
The results indicate that 90% of stroke risk can be explained by 10 risk factors, all of them modifiable.
As expected, hypertension occupied the top position, accounting for 34.6% of population attributable global risk of stroke. But other risk factors were also identified that can highly contribute to the risk.
The factors identified by the INTERSTROKE study are:
- Hypertension – 34.6%
- Regular physical activity – 28.5%
- Waist-to-hip ratio (abdominal obesity) – 26.5%
- Ratio of apolipoproteins (cholesterol, triglycerides)- 24.9%
- Cigarette smoking – 18.9%
- Dietary risk score – 18.8%
- Cardiac causes (atrial fibrillation, flutter, valve disease, history of heart attack) – 6.7%
- Psychological factors
- Stress – 4.6%
- Depression – 5.2%
- Diabetes – 5%
- Alcohol intake – 3.8%
The same risk factors were identified for different stroke subtypes, especially the tow most common. Ischemic and hemorrhagic stroke.
“Along with hypertension, current smoking, abdominal obesity, diet, and physical activity accounted for 80% of the global risk of stroke, explaining 80% of the risk of ischemic stroke and 90% of the risk of hemorrhagic strokes.”
The INTERSTROKE results showed that the risk factors for stroke and heart disease are more or less the same but the importance of each factor may vary. In the case of heart disease (as shown by the INTERHAERT study), 50% of the risks are attributed to lipids. In stroke, high blood pressure is the most important factors.
According to an editorial by Dr Jack Tu
“This finding is particularly relevant, because it highlights the need for health authorities in these regions to screen the general population for high blood pressure and, if necessary, offer affordable treatment to reduce the burden of stroke.”
It is good to know that all the risk factors are modifiable, e.g. lifestyle factors. There is something we can do about them. And we should start now.