Stroke prevention
=================

* Erica Weir

***Background and epidemiology:*** This past May and June, the US Centers for Disease Control and Prevention and the Public Health Agency of Canada each dedicated a month, respectively, to raising awareness about stroke. Each year in Canada stroke occurs in 50 000 people and accounts for 7% of all deaths. About 5% of men over the age of 65 have been affected by stroke; the proportion is only slightly lower for women. Care for stroke patients accounts for 2.1% of Canadian health care expenditures.1 The burden of this devastating disease can be reduced through a combination of clinical interventions targeted at high-risk individuals and broader population-health initiatives to control chronic diseases.2

The causes and mechanisms of stroke vary. Half of cases are atherothrombotic in origin, with a further 25% attributable to small-vessel lacunar disease and 20% to cardioembolism.1 Common conditions that underlie stroke include atherosclerosis, atrial fibrillation, hypertension, dyslipidemia and diabetes.1

Some risk factors for stroke, such as age, gender, ethnicity and genetic factors, cannot be modified. Others, if moderated, can greatly reduce both the likelihood of stroke and the severity of its outcomes: physical inactivity, hypertension, smoking, dyslipidemia, atrial fibrillation, diabetes and heavy use of alcohol.2

***Clinical management:*** Prevention of stroke in individuals with underlying disease was recently and thoroughly reviewed in *CMAJ*.1 Highlights of that review are shown in Table 1.

View this table:
[Table1](http://www.cmaj.ca/content/173/4/363/T1)

Table 1. 

Timely access to medical care for thrombolysis (if indicated) and early treatment with ASA can improve stroke outcomes. Individuals at risk of stroke need to be educated that the warning signs of stroke include sudden weakness, trouble speaking, sudden loss of vision and severe unusual headache or dizziness. This must especially be reinforced in patients who experience a transient ischemic attack (TIA), since the risk of stroke is elevated in the first 48 hours after a TIA and the risk of having a stroke within a year of a TIA is 10%–14%.3

***Prevention:*** A stroke-prevention strategy aimed at the general public that involves education and regulatory changes is potentially less costly than and as effective as those that target high-risk populations. For example, about 26% of Canadian adult men and 18% of women have hypertension, defined as a diastolic blood pressure of 90 mm Hg or more, or a systolic pressure of 140 mm Hg or more. About 40% of such people are unaware they have hypertension. Data from large-cohort studies have suggested that a mere 2 mm Hg reduction in a population's mean diastolic blood pressure can decrease the number of new strokes by as much as 14%, which is comparable to targeted medical treatment of all patients with a diastolic pressure of 95 mm Hg or higher.2

Since many of the risk factors for stroke also contribute to the burden of other chronic diseases, there is growing interest in embedding stroke-prevention programs within a broader strategy of control of chronic disease. This includes special attention to those risk factors that contribute to the largest proportion of new stroke cases: physical inactivity, hypertension and smoking.2

## References

1.  1. O'Rourke F, Dean N, Akhtar N, Shuaib A. Current and future concepts in stroke prevention [review]. CMAJ 2004;170(7):1123-33.
    
    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMDoiMTcwLzcvMTEyMyI7czo0OiJhdG9tIjtzOjIwOiIvY21hai8xNzMvNC8zNjMuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

2.  2. Young TK, Hachiniski V. The population approach to stroke prevention: a Canadian perspective. Clin Invest Med 2003;26:78-86.
    
    [PubMed](http://www.cmaj.ca/lookup/external-ref?access_num=12722841&link_type=MED&atom=%2Fcmaj%2F173%2F4%2F363.atom) 

3.  3. Hill MD, Yiannakoulias N, Jeerakathil, Tu JV, Svenson LW, Schopflocher DP. The high risk of stroke immediately after transient ischemic attack: a population-based study. Neurology 2004;62:2015-20.
    
    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6OToibmV1cm9sb2d5IjtzOjU6InJlc2lkIjtzOjEwOiI2Mi8xMS8yMDE1IjtzOjQ6ImF0b20iO3M6MjA6Ii9jbWFqLzE3My80LzM2My5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=)