PACT Centre Pages - Primary Prevention of Cardiovascular Disease


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Individual changes to diet, smoking and level of physical activity can potentially decrease the burden of CVD. The risk of CHD almost doubles in people who are physically inactive. Eating at least 5 portions of fruit and vegetables per day could lead to an estimated reduction of 20% in overall deaths from chronic diseases, such as heart disease, stroke and some cancers. Adult smoking prevalence has decreased from 28% (2000) to 25% (2003).² A six-point programme is in place to reduce smoking prevalence, including media and education campaigns and reducing availability and supply of tobacco. In England the number of people who quit smoking at 4 week follow up increased by 65% from 124,100 in 2002/03 to 204,900 in 2003/04 (57% of those setting a quit date).² Around 277,000 (77%) of those setting a quit date received nicotine replacement therapy, 30,200 (8%) received bupropion and 3,800 (1%) received both.

The Joint British Societies Coronary Risk Prediction charts aim to assess 10 year risk of CVD (including non-fatal MI and stroke) rather than risk of CHD.³ A 10 year CVD risk of 40% is approximately equal to a 10 year CHD risk of 30%.⁴ The UK Prospective Diabetes Study Risk Engine is a specific risk calculator based on 53,000 patient years of data; it is useful for estimating risk in patients with type 2 diabetes not known to have heart disease.⁵ Research has shown that moderate reductions in several risk factors may be more beneficial than major reductions in one.⁶ The approach to CVD treatment is moving away from treating individual risk factors to assessment of absolute risk of CVD; this may vary more than 20-fold in patients with the same cholesterol or blood pressure levels.⁶

Hypertension

Antihypertensive therapy should be offered to patients with either persistent high blood pressure =160/100mmHg or patients with persistent blood pressure =140/90 mmHg with raised cardiovascular risk (10 year risk of CHD =15% or CVD =20% or existing CVD or target organ damage).⁷ There has been considerable debate over the different approaches to starting treatment taken by the British Hypertension Society (BHS) compared to NICE. However the BHS guidelines agree with NICE that the least expensive drug (usually a thiazide diuretic) should be chosen first line where there are no compelling indications to use an alternative.^3,7 NICE recommends that a beta-blocker is added if necessary.⁷ If the patient is at raised risk of new-onset diabetes then an angiotensin-converting enzyme (ACE) inhibitor should be added instead of the beta-blocker. If further drug treatment is required then a dihydropyridine calcium-channel blocker can be added third line.⁷ More than one drug is usually required to reach target blood pressure. Angiotensin-II receptor antagonists (AIIRAs) are a suitable alternative to ACE inhibitors where cough is a limiting adverse effect. NICE recommends offering patients over 80 years the same treatment as younger patients, taking account of their co-morbidity and existing burden of drug use.

Hyperlipidaemia

The NSF target for primary prevention is to lower total cholesterol to <5mmol/l (low-density lipoprotein (LDL) cholesterol to <3mmol/l) or by 30% whichever is greater in those with a 10 year CHD risk greater than 30%. Although the BHS guidelines advise more rigorous targets of <4mmol/l (LDL cholesterol to <2mmol/l) or by 25% (LDL cholesterol by 30%), for primary prevention in those with a 10 year CVD risk of 20% this is not national policy.³ NICE is reviewing national clinical policy to take into account recent outcome data, this is due for publication in September. Statins are usually only prescribed for high risk patients, which could partly account for the modest decline in standardized admission ratios for acute MI between 1996 and 2002, since MIs often occur in people with lower risk.⁸ Choice of statin therapy depends on clinical evidence and cost-effectiveness, currently simvastatin is the cheapest (see Price Chart) and is a reasonable first-line choice. Debate continues around the benefit of treating all patients at high risk of CVD with a statin regardless of pre-treatment cholesterol level. The effectiveness of atorvastatin 10mg daily was assessed against placebo in primary prevention of CVD in patients with type 2 diabetes. The results were similar to the Heart Protection Study where the benefit from statin treatment appeared to be independent of the initial LDL cholesterol level.⁹ To prevent one CVD event, 27 patients would need to be treated for 4 years with atorvastatin 10mg. Allocation of 1,000 patients to atorvastatin would lead to a reduction of 50 first or subsequent major cardiovascular events over a 4 year follow-up period.⁹ People at lower risk (10-15% 10 year risk of CHD) in addition to reducing their risk by lifestyle modification have the option of purchasing simvastatin 10mg over the counter. For these people, one out of every 20 to 30 who take simvastatin 10mg for three years will have a major cardiovascular event prevented.⁴

Antiplatelet drugs

Low dose aspirin is recommended for patients with CHD or other occlusive arterial disease. There is no good evidence to suggest that any other antiplatelet therapy is more effective than aspirin for long term secondary prevention of serious vascular events.¹⁰ For people who are intolerant of aspirin (proven hypersensitivity to aspirin or a history of severe dyspepsia induced by low dose aspirin) and either have experienced an occlusive vascular event or have symptomatic peripheral arterial disease then clopidogrel alone is recommended.¹¹ Chart 3 shows the year on year increase in prescribing of clopidogrel with a 3.5-fold variation across strategic health authorities. A combination of MR dipyridamole and aspirin is recommended for people who have had an ischaemic stroke or transient ischaemic attack for a period of two years from the most recent event; thereafter, or if MR dipyridamole is not tolerated, the preventative therapy should revert to standard care (including low dose aspirin).¹¹

There are 6.9 million items for beta-blockers (£24.9 million), quarter to December 2004. Of these prescriptions over 65% are for atenolol (22% of total spending on beta-blockers). Bisoprolol is the second most commonly prescribed beta-blocker at 0.7 million items, costing £7.5 million. Over the past 5 years prescribing of beta-blockers has increased by 56%.

Prescribing of renin-angiotensin system drugs has more than doubled in the past 5 years to 8.8 million items and £129.1 million, quarter to December 2004. ACE inhibitors account for 6.5 million items with 2.3 million items for AIIRAs. Ramipril is the most commonly prescribed ACE inhibitor (2.4 million items, £30.3 million) and losartan is the most commonly prescribed AIIRA (0.7 million items, £21.1 million).

Prescribing of lipid regulating drugs has risen by over 250% while spending has risen by 170% over the last 5 years (8.2 million items and £192.8 million, quarter to December 2004). Statins account for 95% of items for lipid regulating drugs (simvastatin 3.6 million and atorvastatin 3.1 million items per quarter). Twice as much is now spent on atorvastatin than simvastatin (£100.2 million compared to £51.4 million). Ezetimibe prescribing and spending has risen to 107,000 items and £3.7 million.

Prescribing of antiplatelet drugs has shown an 83% increase over the past 5 years, with cost increasing almost 5-fold. In the quarter to December 2004, aspirin accounts for 86% of the 7.2 million antiplatelet items prescribed and 14% of the £39.7 million cost. Clopidogrel is the second most commonly prescribed antiplatelet at 0.7 million items and 75% (£30.4 million) of cost for this group.

REFERENCES

1. Petersen S, Peto V and Rayner M. Coronary heart disease statistics. British Heart Foundation : London. June 2004
2. Department of Health. Coronary Heart Disease National Service Framework. Leading the way - Progress report. March 2005.
3. British Hypertension Society guidelines for hypertension management 2004: summary. BMJ 2004; 328: 634-640
4. National Prescribing Centre. Updating local policies for reducing the impact of cardiovascular disease. Where does OTC simvastatin fit in
5. December 2004
6. UKPDS Risk Engine. www.dtu.ox.ac.uk/riskengine
7. Jackson R, Lawes C, Bennett D, Milne R, Rodgers A. Treatment with drugs to lower blood pressure and blood cholesterol based on an individual’s absolute cardiovascular risk. Lancet 2005; 365: 434 – 441
8. NICE. Management of hypertension in adults in primary care. August 2004
9. Majeed A, Aylin P, Williams S, Bottle A, Jarman B. Prescribing of lipid regulating drugs and admissions for myocardial infarction in England. BMJ 2004; 329: 645
10. Colhoun H, Betteridge D, Durrington P, Hitman G, et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet 2004; 364: 685 – 697
11. Clinical Evidence freelance writers. Stroke prevention. Clinical Evidence 2004;12: 253 – 284
12. NICE. Clopidogrel and modified-release dipyridamole in the secondary prevention of occlusive vascular events. October 2004

• Moderate reductions in several cardiovascular risk factors are probably more beneficial than a major reduction in one.
• Low dose thiazide diuretics are usually the starting point for treatment of hypertension, however, more than one drug is often required to achieve current blood pressure targets.
• Simvastatin is a rational first line choice for lipid lowering based on clinical evidence and cost-effectiveness.
• Aspirin is still the most cost-effective therapy for long term secondary prevention of serious vascular events.