a) Background:
Stroke is a major global health problem. It is the third leading cause of death and the leading cause of adult disability. INTERHEART, a global case-control study of acute myocardial infarction in 52 countries (29,972 participants), identified nine modifiable risk factors that accounted for >90% of population-attributable risk. However, traditional risk factors (e.g. hypertension, cholesterol) appear to exert contrasting risks for stroke compared with coronary heart disease, and the etiology of stroke is far more heterogeneousThe contribution of various risk factors to the burden of stroke worldwide is unknown, particularly in countries of low and middle income. The study aimed to establish the association of known and emerging risk factors with stroke and its primary subtypes, assess the contribution of these risk factors to the burden of stroke, and explore the differences between risk factors for stroke and myocardial infarction
b) Aim/objective
1. To estimate the strength of association of conventional and emerging risk factors for stroke and
within stroke subtypes.
2. To determine the population attributable risk [PAR] of these risk factors for stroke.
3. To determine if the risk factors and PAR for different strokes and its subtypes differ from those for
IHD (comparison with INTERHEART).
4. To describe the knowledge of stroke risk factors and major stroke symptoms.
c) Methods:
We completed a standardised international case-control study in 32 countries in Asia, America, Europe, Australia, the Middle East, and Africa. Cases were patients with acute fi rst stroke (within 5 days of symptom onset and 72 h of hospital admission). Controls were hospital-based or community-based individuals with no history of stroke, and were matched with cases, recruited in a 1:1 ratio, for age and sex. All participants completed a clinical assessment and were requested to provide blood and urine samples. Odds ratios (OR) and their population attributable risks (PARs) were calculated, with 99% confi dence intervals.
d) Results:
Between Jan 11, 2007, and Aug 8, 2015, 26 919 participants were recruited from 32 countries (13 447 cases [10 388 with ischaemic stroke and 3059 intracerebral haemorrhage] and 13 472 controls). Previous history of hypertension or blood pressure of 140/90 mm Hg or higher (OR 2·98, 99% CI 2·72–3·28; PAR 47·9%, 99% CI 45·1–50·6), regular physical activity (0·60, 0·52–0·70; 35·8%, 27·7–44·7), apolipoprotein (Apo)B/ApoA1 ratio (1·84, 1·65–2·06 for highest vs lowest tertile; 26·8%, 22·2–31·9 for top two tertiles vs lowest tertile), diet (0·60, 0·53–0·67 for highest vs lowest tertile of modifi ed Alternative Healthy Eating Index [mAHEI]; 23·2%, 18·2–28·9 for lowest two tertiles vs highest tertile of mAHEI), waist-to-hip ratio (1·44, 1·27–1·64 for highest vs lowest tertile; 18·6%, 13·3–25·3 for top two tertiles vs lowest), psychosocial factors (2·20, 1·78–2·72; 17·4%, 13·1–22·6), current smoking (1·67, 1·49–1·87; 12·4%, 10·2–14·9), cardiac causes (3·17, 2·68–3·75; 9·1%, 8·0–10·2), alcohol consumption (2·09, 1·64–2·67 for high or heavy episodic intake vs never or former drinker; 5·8%, 3·4–9·7 for current alcohol drinker vs never or former drinker), and diabetes mellitus (1·16, 1·05–1·30; 3·9%, 1·9–7·6) were associated with all stroke. Collectively, these risk factors accounted for 90·7% of the PAR for all stroke worldwide (91·5% for ischaemic stroke, 87·1% for intracerebral haemorrhage), and were consistent across regions (ranging from 82·7% in Africa to 97·4% in southeast Asia), sex (90·6% in men and in women), and age groups (92·2% in patients aged ≤55 years, 90·0% in patients aged >55 years). We observed regional variations in the importance of individual risk factors, which were related to variations in the magnitude of ORs (rather than direction, which we observed for diet) and diff erences in prevalence of risk factors among regions. Hypertension was more associated with intracerebral haemorrhage than with ischaemic stroke, whereas current smoking, diabetes, apolipoproteins, and cardiac causes were more associated with ischaemic stroke (p<0·0001).
e) Total recruitment & no. of sites:
Global 27,587 from 32 countries, India : 5,054 from 20 sites
f) Conclusion:
Ten potentially modifiable risk factors are collectively associated with about 90% of the PAR of stroke in each major region of the world, in ethnic groups, in men and women, and in diff erent age groups. However, we found important regional variations in the relative importance of most individual risk factors for stroke, which could contribute to worldwide variations in frequency and case-mix of stroke and support the development of both global and region-specifi c programmes to prevent stroke. Targeted interventions that reduce blood pressure and smoking, and promote physical activity and a healthy diet, could substantially reduce the burden of stroke.
g) Publication status (Name & year):
Neuroepidemiology 2010, 2021; Lancet 2010, 2016
h) Publication link:
https://pubmed.ncbi.nlm.nih.gov/33951632/
https://pubmed.ncbi.nlm.nih.gov/20389123/
https://pubmed.ncbi.nlm.nih.gov/27431356/
i) Updated as on: 30th June 2023