Heart and stroke risk: a catalyst for conversation

Published in MedicineWise News

Date published: About this date

Clinical content may change after this date. This information is not intended as a substitute for medical advice from a qualified health professional. Health professionals should rely on their own expertise and enquiries when providing medical advice or treatment.

Practice points | Statins — an effective drug strategy for reducing CVD risk | Treat with lipid-lowering drugs in line with absolute CVD risk | Determining absolute CVD risk — who needs assessing and how? | Risk assessment tools | Assessing and managing risk in people aged over 74 | Account for other risk factors | Patients at high CVD risk — drug treatment recommended | Patients at moderate CVD risk — drug treatment not routinely recommended | Patients at low CVD risk — focus on lifestyle | Managing lifestyle factors | References

Key points

  • Various media reports have linked statins to a variety of adverse events, but these drugs remain one of the most effective strategies for reducing the risk of cardiovascular disease.
  • Guidelines recommend basing lipid (and other risk factor) management on absolute cardiovascular disease risk. However, more than 10 years on since the introduction of these recommendations statin prescribing does not always reflect a patient's need based on absolute cardiovascular disease risk.
  • Recently both Therapeutic Guidelines and the National Vascular Disease Prevention Alliance updated their recommendations on management of absolute cardiovascular disease risk.
  • Find out who needs a risk calculation before treatment and what the assessment and treatment recommendations in Australia are.

Practice points

  • Base starting statin treatment in patients under age 75 on their absolute CVD risk.1
  • Determine absolute CVD risk of Australian patients using the Australian cardiovascular disease risk charts or associated web calculator.1
  • Base the decision to start treatment in people over 74 on clinical judgement. Their absolute CVD risk score can be used to inform management but do not inflate calculated absolute risk because of age > 75 years. The web calculator corrects for this by requiring maximum age entered to be <75, regardless of actual age.2
  • In people in risk categories that put them at high risk of a cardiovascular event (see Box 1), treat with statins and BP-lowering medication. These people do not need a risk calculation.1,2
  • Assess absolute CVD risk in all other patients aged ≥ 45 years, or ≥ 35 for Aboriginal and Torres Strait Islander peoples, to determine the need for lipid-lowering treatment.1
  • Assess absolute CVD risk every 2 years for people at low risk, every 6–12 months for people at medium risk, and according to clinical context for people at high risk.2
  • Explain to patients at high absolute CVD risk that the aims of treatment are to reduce their overall CVD risk and that they will benefit from combined BP- and lipid-lowering medications even if their individual levels of these risk factors are not elevated.1
  • Highlight the importance of lifestyle changes for all patients.1

Statins — an effective drug strategy for reducing CVD risk

CVD is largely preventable but still the most common cause of death in Australia and was responsible for more than one-third of deaths in 2008.2

High plasma cholesterol is an established modifiable risk factor for CVD, and lowering levels of LDL–C  plays an important role in preventing cardiovascular events.2

Statins are the most effective lipid-modifying drugs and are the first-line treatment for LDL-C lowering.2 Statins reduce the risk of cardiovascular events and death for people at elevated CVD risk, regardless of their initial lipid levels.3,4

The benefit of a statin is greatest for those at greatest absolute risk of a cardiovascular event, including those with established CVD.3,4

With conflicting evidence about the benefits and harms of statins5-7 and recent national and international safety updates8-10 it is important that statins are used in the people for whom the benefits are most likely to outweigh the potential harms.

Here we review current guidelines to highlight who needs statin treatment and how to identify them.

Treat with lipid-lowering drugs in line with absolute CVD risk

Guidelines recommend that absolute CVD assessment should provide the basis of CVD risk assessment and treatment.1

Assessment of CVD risk on the basis of the combined effect of multiple risk factors reflects a person's overall risk of CVD and is more accurate than assessment of individual risk factors.1 This forms the basis of an absolute CVD risk assessment.

Absolute CVD risk is defined as the probability (as a percentage) of a person having a cardiovascular event over a pre-defined period — in the case of Australian guidelines within a 5-year period.2

Guidelines have recommended absolute CVD risk as the basis for lipid management for more than 10 years.11,12 However, treatment with lipid-modifying drugs such as statins often doesn't reflect the person's absolute CVD risk.13-16 This can lead to under-treatment of eligible people and the inappropriate treatment of others.13-16

Determining absolute CVD risk — who needs assessing and how?

People in certain risk categories (Box 1) do not need an absolute CVD risk assessment, as they are known to be at high risk of a cardiovascular event.

People at high CVD risk require simultaneous treatment with lipid-modifying and BP-lowering medication (unless contraindicated or clinically inappropriate) in addition to lifestyle advice, but they do not require risk calculation.1

Box 1: Who doesn't need a risk assessment?1

People for whom high CVD risk can be assumed do not need an absolute CVD risk assessment using the Framingham Risk Equation. This includes people with:1,2

  • Established CVD
  • Diabetes and aged > 60 years
  • Diabetes with microalbuminuria (albumin excretion > 20 micrograms/min or urinary albumin:creatinine ratio > 2.5 mg/mmol for males or > 3.5 mg/mmol for females)
  • Moderate or severe chronic kidney disease (persistent proteinurea or
    eGFR
    < 45 mL/min/1.73m2)
  • A previous diagnosis of familial hypercholesterolaemia
  • Systolic BP ≥ 180 mmHg or diastolic BP ≥ 110 mmHg
  • Serum total cholesterol > 7.5 mmol/LA
  • Aboriginal and Torres Strait Islander adults aged over 74
A People with serum total cholesterol > 7.5 mmol/L are included on the assumption that this is due to increased levels of LDL-C (eg, > 5.5 mmol/L) or non-HDL cholesterol (eg, > approximately 6.5 mmol/L).

For all other patients aged 45–74 (≥ 35 for Aboriginal and Torres Strait Islander peoples), use a risk tool to estimate absolute CVD risk accurately.1,2 The risk tool should be one that is validated in the target patient population.1

Risk assessment tools

For the Australian population Therapeutic Guidelines recommends using the National Vascular Disease Prevention Alliance (NVDPA) absolute cardiovascular disease risk charts18 or associated web-based calculator.19 These were developed using the Framingham Risk Equation,20 which takes into account:

  • sex
  • age
  • BP
  • smoking status
  • total and HDL-C (or their ratio)
  • diabetes status
  • left ventricular hypertrophy on ECG  (if known).

Risk is categorised according to probability of a cardiovascular event in the next 5 years: high (> 15%), moderate (10% to 15%) or low (< 10%).1,2

Assessing and managing risk in people aged over 74

Age is probably the most significant risk factor for CVD.2 However, on its own, it is neither a reason to start nor to contraindicate drug treatment in patients.2 Base the decision to start treatment in these people on clinical judgement taking into account:2

  • likely benefits and risks of treatment
  • life expectancy
  • comorbidities and quality of life
  • the patient's personal values.

New guidelines for the management of absolute CVD risk developed by the NVDPA were published in 2012, coinciding with the most recent update to Therapeutic Guidelines.1,2

In a change to previous guidance,21 the Framingham Risk Equation can now be used to estimate minimum absolute CVD risk in patients aged over 74 who do not have CVD and are not in one of the high-risk categories listed in Box 1.1,2.

The tool has not been validated in these patients, but the estimate may be used to guide management and may help discriminate between patients at moderate and high absolute risk.2 When using the web calculator tool, to avoid inflating the calculated absolute risk for people aged > 74 their age should be entered as 74, regardless of actual age.1,2

Account for other risk factors

Risk tools can help guide management but do not replace a full CVD assessment, as it is important to also take into account various risk factors that are not addressed in the Framingham Risk Equation.1

A comprehensive assessment includes consideration of modifiable risk factors, non-modifiable risk factors and related conditions (see Box 2).1,2 The assessment should check for groups in which the tool can underestimate risk, for example:

  • Aboriginal and Torres Strait Islander peoples
  • certain ethnic groups
  • people with diabetes (aged 45–60)
  • overweight or obese people
  • people of low socioeconomic status.

When these additional factors are present, treat the risk calculated by the tool as a minimum estimate and adjust it using clinical judgement.2

This is especially important for people determined to be at moderate risk by the tool and who may be considered to need drug treatment based on their additional risk factors.1

Box 2. Risk factors for cardiovascular disease1

Modifiable risk factors

  • Smoking statusB
  • Elevated BPB
  • DiabetesB
  • DyslipidaemiaB
  • Central obesity, waist circumference and BMI
  • Poor nutrition
  • Sedentary lifestyle
  • Excessive alcohol intake

Non-modifiable risk factors

  • AgeB
  • SexB
  • Family history of premature CVDC
  • Social history, including cultural identity and ethnicity (e.g. Aboriginal and Torres Strait Islander, South Asian, Maori and Pacific Islander, Middle Eastern peoples), and lower socioeconomic status

Related conditions

  • Left ventricular hypertrophy as diagnosed by ECGB
  • Chronic kidney disease (albuminuria ± urine protein, eGFR)2
  • Familial hypercholesterolaemia
  • Evidence of atrial fibrillation (history, examination, ECG)2
  • Mental health (e.g. depression)
B These risk factors are included in the absolute risk calculator, based on the Framingham risk equation.

C Cardiovascular disease occurring in a first-degree relative aged < 60 years.

Patients at high CVD risk — drug treatment recommended

Treat people at high absolute risk of CVD with lipid-lowering and BP-lowering medication concomitantly unless contraindicated or clinically inappropriate.1,2

Ensure these people also receive frequent and sustained advice and support about diet and physical activity and stopping smoking to facilitate beneficial lifestyle changes alongside pharmacotherapy.1,2

(See Assessing and managing risk in people aged over 74 for additional considerations in this population).

See the August 2013 Health News and Evidence article Stop smoking — what works for your patients? for further details of helping patients quit smoking.

Patients at moderate CVD risk — drug treatment not routinely recommended

Pharmacotherapy, including treatment with statins, is not routinely recommended for people at moderate risk of CVD.

Provide these people with appropriate specific advice and support about diet and physical activity as well as appropriate advice, support and drug therapy for stopping smoking.1

Consider BP-reducing and/or lipid-modifying therapy (in addition to behavioural risk factor advice) for these people if 3–6 months of behavioural risk factor modification does not reduce their absolute CVD risk or if:1,2

  • their BP is persistently > 160/100 mmHg
  • they have a family history of premature CVD
  • they are of a specific population for which Framingham Risk Equation underestimates their risk.

Discuss the benefits and harms of drug treatment with these patients, as the absolute benefits may be outweighed by the potential harms (e.g. adverse effects, cost).1

Patients at low CVD risk — focus on lifestyle

The costs and, to a lesser extent, the potential harms of lipid-modifying drugs probably exceed the benefits for people at low risk,22 and drug treatment is not routinely recommended.1 Intervening early with lifestyle changes is the priority (see Managing lifestyle factors section below).

Give these people brief general advice regarding diet and physical activity along with appropriate advice, support and drug therapy for smoking cessation.1

Guidelines recommend that BP-lowering therapy is considered alongside lifestyle advice for these people if their BP is persistently > 160/100 mmHg.1

Repeat the risk assessment every 2 years for people at low risk (to coincide with their BP check), every 6–12 months for people at moderate risk and according to clinical context for people at high risk.2

Managing lifestyle factors

Lifestyle changes should be recommended for everyone and discussed during consultations that assess CVD risk.

Lifestyle changes reduce the risk of cardiovascular events by means independent of lipid lowering;23 they can curb the progression of atherosclerosis24,25 and are effective in primary and secondary prevention of CVD.1

For further information on the benefits of lifestyle change see:

References
  1. eTG complete [online]. Therapeutic Guidelines: Cardiovascular. Melbourne: 2012. [Online] (accessed 16 May 2013).
  2. National Vascular Disease Prevention Alliance. Guidelines for the management of absolute cardiovascular disease risk. 2012. [Full text] (accessed 19 August 2013).
  3. Baigent C, Keech A, Kearney PM, et al. Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet 2005;366:1267–78. [PubMed]
  4. Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002;360:7–22. [PubMed]
  5. Undela K, Srikanth V, Bansal D. Statin use and risk of breast cancer: a meta-analysis of observational studies. Breast Cancer Research & Treatment 2012;135:261–9. [PubMed]
  6. McDougall JA, Malone KE, Daling JR, et al. Long-term statin use and risk of ductal and lobular breast cancer among women 55 to 74 years of age. Cancer Epidemiol Biomarkers Prev 2013. [PubMed]
  7. Dormuth CR, Hemmelgarn BR, Paterson JM, et al. Use of high potency statins and rates of admission for acute kidney injury: multicenter, retrospective observational analysis of administrative databases. BMJ 2013;346:f880. [PubMed]
  8. Australian Government Department of Health and Ageing Therapeutic Goods Administration. Simvastatin: new contraindications, precautions and dosage recommendations. 2011. [Online] (accessed 16 April 2013).
  9. Australian Government Department of Health and Ageing Therapeutic Goods Administration. Statins. 2012. [Online] (accessed 19 April 2013).
  10. U.S. Food and Drug Administration. FDA Drug Safety Communication: Important safety label changes to cholesterol-lowering statin drugs. 2012. [Online] (accessed 19 April 2013).
  11. National Heart Foundation of Australia & The Cardiac Society of Australian and New Zealand. Lipid management guidelines – 2001. National Heart Foundation of Australia, The Cardiac Society of Australia and New Zealand. Med J Aust 2001;175[suppl]:S57–85. [PubMed]
  12. Tonkin A, Barter P, Best J, et al. National Heart Foundation of Australia and the Cardiac Society of Australia and New Zealand. Position statement on lipid management 2005. Heart Lung Circ 2005;14:275–91. [PubMed]
  13. Wu J, Zhu S, Yao GL, et al. Patient factors influencing the prescribing of lipid lowering drugs for primary prevention of cardiovascular disease in UK general practice: A National Retrospective Cohort Study. PLoS One 2013;8:e67611. [PubMed]
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  15. Peiris DP, Patel AA, Cass A, et al. Cardiovascular disease risk management for Aboriginal and Torres Strait Islander peoples in primary health care settings: findings from the Kanyini Audit. Med J Aust 2009;191:304–9. [PubMed]
  16. Webster RJ, Heeley EL, Peiris DP, et al. Gaps in cardiovascular disease risk management in Australian general practice. Med J Aust 2009;191:324–9. [PubMed]
  17. Central Australian Rural Practitioners Association (CARPA). CARPA Standard Treatment Manual, 5th edn. 2009. Alice Springs: Central Australian Rural Practitioners Association Inc.
  18. National Heart Foundation of Australia (National Blood Pressure and Vascular Disease Advisory Committee). Guide to management of hypertension 2008. Updated December 2010. [Fulltext] (accessed 4 September 2013).
  19. National Vascular Disease Prevention Alliance. Australian absolute cardiovascular disease risk calculator. 2012. [Online] (accessed 5 September 2013).
  20. Anderson KM, Odell PM, Wilson PW, et al. Cardiovascular disease risk profiles. Am Heart J 1991;121:293–8. [PubMed]
  21. National Vascular Disease Prevention Alliance. Guidelines for the assessment of absolute cardiovascular disease risk. 2009.
  22. Ward S, Lloyd Jones M, Pandor A, et al. A systematic review and economic evaluation of statins for the prevention of coronary events. Health Technol Assess 2007;11:1–160, iii–iv. [PubMed]
  23. Grundy SM, Cleeman JI, Merz CN, et al. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines. Circulation 2004;110:227–39. [PubMed]
  24. National Cholesterol Education Program Expert Panel (US). Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATP III Final Report), National Heart, Lung and Blood Institute, National Institutes of Health, 2002. [Online] (accessed 3 September 2010).
  25. Ornish D, Scherwitz LW, Billings JH, et al. Intensive lifestyle changes for reversal of coronary heart disease. JAMA 1998;280:2001–7. [PubMed]
Special thanks to David Sullivan, Clinical Associate Professor, Royal Prince Alfred Hospital Sydney for reviewing this article.