Professor Jonathan Mant summarises top tips for patients and practitioners on stroke risk assessment and reduction

mant jonathan

Professor Jonathan Mant

20160729 independent content logo with text (rgb)

Read this article to learn more about:

  • modifiable risk factors for stroke, including diet and lifestyle
  • how to assess a person’s risk of stroke
  • therapies that are effective at reducing risk of stroke.

There are over 100,000 strokes in the UK per year. It is the fourth commonest cause of death, and is a leading cause of disability in the UK, with over 1.2 million survivors, costing the NHS and social care around £1.7 billion a year.1 Much can be done to reduce this burden of disease through prevention—the large INTERSTROKE case control study suggests that modifiable risk factors potentially account for 90% of all stroke cases.2

1. Advise patients to eat a healthy diet

Diet has a big impact on stroke risk. Changing diet can help a patient to reduce their risk of stroke in several different ways:

  • reducing dietary sodium intake and increasing fruit and vegetable consumption will lower blood pressure, an important risk factor for stroke (see below)3,4
  • a diet rich in fruit, vegetables, nuts, fish, and olive oil—the so-called ‘Mediterranean diet’—will reduce risk of stroke and myocardial infarction5
  • weight loss will reduce body mass index (BMI), which is in turn a risk factor for stroke (at least down to a BMI of 22.5).6

2. Encourage patients to adopt a healthy lifestyle

As well as diet, changing other lifestyle habits can help to reduce stroke risk.

Physical activity

  • Any physical activity compared to inactivity is associated with reduced risk of stroke.7

Smoking

  • Smoking is associated with a 2–3-fold increase in risk of death from stroke. Stopping smoking, even at older ages, will have an effect on future stroke risk.8,9

Alcohol

  • Alcohol consumption is associated with increased stroke risk, with each 100 g (i.e approximately 12 units) associated with a 14% increase in risk.10

3. Use a cardiovascular disease risk calculator to assess stroke risk

Risk factors for stroke and coronary heart disease overlap, so for practical purposes, a cardiovascular disease risk calculator (rather than a stroke-specific risk calculator) is appropriate to identify high-risk individuals and inform treatment options.

For a UK population, NICE recommends that cardiovascular risk is assessed using the QRISK2® tool.11 Since publication of this guideline, however, the tool has been updated to QRISK3®. An open source online web-calculator is available to estimate cardiovascular risk using the QRISK3® algorithm (qrisk.org/three).12 This tool is not applicable to people with existing cardiovascular disease. Factors that are considered by QRISK3® calculator are listed in Box 1.13

Box 1: Factors included in QRISK3® for estimating cardiovascular risk12,13

  • demographic
    • age
    • sex
    • ethnicity
    • postcode
  • conventional cardiovascular risk factors:
    • blood pressure, including a measure of variability
    • total cholesterol:high-density lipoprotein (HDL) cholesterol ratio
    • smoking status
    • BMI
    • angina or heart attack in first-degree relative aged less than 60 years
  • existing conditions
    • diabetes
    • atrial fibrillation
    • migraine
    • rheumatoid arthritis
    • systemic lupus erythematosus
    • severe mental illness
    • erectile dysfunction
    • chronic kidney disease (stage 3, 4, or 5)
  • medication
    • steroids
    • atypical anti-psychotic
    • blood pressure treatment.

4. Treat high blood pressure

Hypertension is a major risk factor for stroke so it is important to treat high blood pressure. NICE Clinical Guideline (CG) 127 recommends that blood pressure lowering treatment is offered to:14

  • all people with a clinic blood pressure of 160/100 mmHg or higher and a subsequent daytime ambulatory blood pressure monitoring (ABPM) of 150/95 mmHg or higher
  • people with a clinic blood pressure of 140/90 mmHg or higher and a subsequent daytime ABPM of 135/85 mmHg or higher, who have one or more of the following:
    • target organ damage
    • established cardiovascular disease
    • renal disease
    • diabetes
    • a 10-year cardiovascular risk of 20% or greater.

Recent US guidelines have recommended lower blood pressure thresholds for treatment, largely it would seem on the basis of the SPRINT trial.15–17 This interpretation of the evidence is controversial, as it potentially results in treating nearly half the adult population with blood pressure lowering drugs, and for people at low cardiovascular risk, the reduction in risk may not be worth the impact of treatment.17

5. Offer statin therapy

Statin therapy is effective at reducing risk of stroke, and should be offered to people depending upon their underlying cardiovascular risk. NICE CG181 recommends that atorvastatin 20 mg/day is offered to people with a 10-year cardiovascular risk ≥10%.11 There is strong evidence from randomised controlled trials that use of statins lowers risk of stroke and other cardiovascular events and increases life expectancy.18 These benefits outweigh the potential adverse effects of statins: myopathy (which is reversible on stopping the therapy); new onset diabetes mellitus; and haemorrhagic stroke.19 True myopathy is rare, occurring in 5 people for every 10,000 treated for 5 years.19 In placebo-controlled trials, the incidence of muscle pain and weakness was no greater in the statin arm than in the placebo arm.19

6. Take opportunities to case find atrial fibrillation

Opportunistic case finding is an effective way to identify atrial fibrillation (AF), an important risk factor for stroke. Atrial fibrillation is associated with a nearly five-fold increase in risk of stroke.20 Case finding, whether by simple pulse palpation followed by a full electrocardiogram (ECG) if positive, or by single lead ECG, is effective at identifying previously unidentified AF.21

7. Offer anticoagulation to most people with AF to prevent stroke

Anticoagulation is highly effective at reducing the risk of stroke in people with AF.22 NICE CG180 recommends that anticoagulation is offered on the basis of assessment of stroke risk using the CHA2DS2-VASc score,23 and consideration of bleeding risk (the principal side-effect of therapy) using the HAS-BLED score:24,25

  • consider anticoagulation for men with a CHA2 DS2 -VASc score of 1, and offer anticoagulation to people with a CHA2DS2-VASc score of 2 or above. Take the bleeding risk into account.

CHA2 DS2-VASc: congestive heart failure/left ventricular dysfunction 1 point; hypertension 1 point; age ≥75 years 2 points; diabetes mellitus 1 point; stroke/transient ischaemic attack/thromboembolism 2 points; vascular disease 1 point; age 65–74 1 point; female sex 1 point.

HAS-BLED: 1 point each for: hypertension (systolic blood pressure >160 mmHg); abnormal renal function; abnormal liver function; stroke; labile international normalised ratios (INRs); bleeding; age >65 years; antiplatelet agents or non-steroidal anti-inflammatory drugs; alcohol.

8. Arrange urgent specialist assessment after TIA

The early risk of completed stroke after a transient ischaemic attack (TIA) is high—about 5% within a week26—so urgent specialist assessment and treatment of possible TIAs is required. This risk can be modified by prompt secondary prevention treatment, particularly with aspirin,27 and further investigation may reveal underlying causes such as carotid stenosis or atrial fibrillation. The National clinical guideline for stroke recommends:26

  • ‘patients with acute neurological symptoms that resolve completely within 24 hours (i.e. suspected TIA) should be given aspirin 300 mg immediately and assessed urgently within 24 hours by a specialist physician in a neurovascular clinic or an acute stroke unit.’

9. Offer antithrombotic therapy to people with stable cardiovascular disease

Existing cardiovascular disease is an important risk factor for further cardiovascular events and the risk can be reduced by antiplatelet therapy. NICE recommends:28

  • ‘offer aspirin to all people after an MI and continue it indefinitely, unless they are aspirin intolerant or have an indication for anticoagulation.’

Evidence from the COMPASS trial suggests that some people may benefit from dual therapy of aspirin with low-dose rivaroxaban (2.5 mg twice daily), as this combination reduces risk of further cardiovascular events more than aspirin alone.29 However, this benefit is partly offset by an increased risk of bleeding, so decision making will need to weigh up the individual risks and benefits.

10. Consider all secondary prevention options

People who have had a stroke are at high risk of a second stroke so all secondary prevention options should be considered. The National clinical guideline for stroke recommends:26

  • ‘people with stroke or TIA should receive a comprehensive and personalised strategy for vascular prevention including medication and lifestyle factors, which should be implemented as soon as possible and should continue long-term’

Therefore, all the factors considered above should be taken on board.

Jonathan Mant, Professor of Primary Care Research,

Primary Care Unit, Department of Public Health & Primary Care, University of Cambridge

References

  1. Stroke Association. State of the nation—stroke statistics, January 2017. Stroke Association, 2017. Available at: www.stroke.org.uk/sites/default/files/state_of_the_nation_2017_final_1.pdf
  2. O’Donnell M, Chin S, Rangarajan S et al. Global and regional effects of potentially modifiable risk factors associated with acute stroke in 32 countries (INTERSTROKE): a case-control study. Lancet 2016; 388 (10046): 761–775.
  3. Sacks F, Svetkey L, Vollmer W et al for the DASH-Sodium Collaborative Research Group. Effects on blood pressure of reduced dietary sodium and the dietary approaches to stop hypertension (DASH) diet. New Engl J Med 2001; 344 (1): 3–10.
  4. John J, Ziebland S, Yudkin P et al for the Oxford Fruit and Vegetable Study Group. Effects of fruit and vegetable consumption on plasma antioxidant concentrations and blood pressure: a randomised controlled trial. Lancet 2002; 359 (9322): 1969–1974.
  5. Estruch R, Ros E, Salas-Salvado J et al for the PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet. New Engl J Med 2013; 368 (14): 1279–1290.
  6. Di Angelantonio E, Bhupathiraju S, Wormser D et al for the Global BMI Mortality Collaboration. Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents. Lancet 2016; 388 (10046): 776–786.
  7. Wendel-Vos G, Schuit A, Feskens E et al. Physical activity and stroke. A meta-analysis of observational data. Int J Epidemiol 2004; 33 (4): 787–798.
  8. Pirie K, Peto R, Reeves G, Green J, Beral V, for the Million Women Study Collaborators. The 21st century hazards of smoking and benefits of stopping: a prospective study of one million women in the UK. Lancet 2013; 381 (9861): 133–141.
  9. Doll R, Peto R, Boreham J, Sutherland I. Mortality in relation to smoking: 50 years’ observations on male British doctors. BMJ 2004; 328: 1519.
  10. Wood A, Kaptoge S, Butterworth A et al for the Emerging Risk Factors Collaboration/EPIC-CVD/UK Biobank Alcohol Study Group. Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599,912 current drinkers in 83 prospective studies. Lancet 2018; 391 (10129): 1513­–1523.
  11. NICE. Cardiovascular disease: risk assessment and reduction, including lipid modification. Clinical Guideline 181. NICE, 2014 (updated 2016). Available at: www.nice.org.uk/cg181
  12. ClinRisk. Welcome to the QRISK® 3-2017 risk calculator. qrisk.org/three/ (accessed 2 May 2018).
  13. Hippisley-Cox J, Coupland C, Brindle P. Development and validation of QRISK3 risk prediction algorithms to estimate future risk of cardiovascular disease: prospective cohort study. BMJ 2017; 357: j2099.
  14. NICE. Hypertension in adults: diagnosis and management. Clinical Guideline 127. NICE, 2011 (updated 2016). Available at: www.nice.org.uk/cg127
  15. Whelton P, Carey R, Aronow W et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology American Heart Association Task Force on Clinical Practice Guidelines. Hypertension 2017; doi: 10.1161/HYP.0000000000000065.
  16. Wright J, Williamson J, Whelton P et al for the SPRINT Research Group. A randomized trial of intensive versus standard blood-pressure control. N Engl J Med 2015; 373 (22): 2103–2116.
  17. McManus R, Mant J. Hypertension: New US blood-pressure guidelines—who asked the patients? Nat Rev Cardiol 2018; 15 (3): 137–138.
  18. Fulcher J, O’Connell R, Voysey M et al for the Cholesterol Treatment Trialists’ Collaboration. Efficacy and safety of LDL-lowering therapy among men and women: meta-analysis of individual data from 174,000 participants in 27 randomised trials. Lancet 2015; 385 (9976): 1397–1405.
  19. Collins R, Reith C, Emberson J et al. Interpretation of the evidence for the efficacy and safety of statin therapy. Lancet 2016; 388 (10059): 2532–2561.
  20. Wolf P, Abbott R, Kannel W. Atrial fibrillation as an independent risk factor for stroke: the Framingham Study. Stroke 1991; 22 (8): 983–988.
  21. Freedman B, Camm J, Calkins H et al. Screening for atrial fibrillation—a report of the AF-SCREEN International Collaboration. Circulation 2017; 135 (19): 1851–1867.
  22. Hart R, Pearce L, Aguilar M. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation. Ann Intern Med 2007; 146 (12): 857–867.
  23. Olesen J, Lip G, Hansen M et al. Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study. BMJ 2011; 342: d124.
  24. NICE. Atrial fibrillation: management. Clinical Guideline 180. NICE, 2014. Available at: www.nice.org.uk/cg180
  25. Pisters R, Lane D, Nieuwlaat R et al. A novel user-friendly score (HAS-BLED) to assess 1-year risk of major bleeding in patients with atrial fibrillation: the Euro Heart Survey. Chest 2010; 138: 1093–1100.
  26. Intercollegiate Stroke Working Party. National clinical guideline for stroke—fifth edition 2016. Royal College of Physicians, 2016. Available at: www.strokeaudit.org/SupportFiles/Documents/Guidelines/2016-National-Clinical-Guideline-for-Stroke-5t-(1).aspx
  27. Rothwell P, Algra A, Chen Z et al. Effects of aspirin on risk and severity of early recurrent stroke after transient ischaemic attack and ischaemic stroke: time-course analysis of randomised trials. Lancet 2016; 388 (10042): 365–375.
  28. NICE. Myocardial infarction: cardiac rehabilitation and prevention of further cardiovascular disease. Clinical Guideline 172. NICE, 2013. Available at: www.nice.org.uk/cg172
  29. Eikelboom J, Connolly S, Bosch J et al for the COMPASS Investigators. Rivaroxaban with or without aspirin in stable cardiovascular disease. New Engl J Med 2017; 377: 1319–1330.