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Prevention of coronary heart disease in general practice
University of Southampton, UK
E-mail: nick.dunn{at}soton.ac.uk
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Abstract |
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TOP
Abstract
What the GP curriculum...Coronary heart disease in the UK is a very common problem. Coronary heart disease (CHD) causes over 117,000 deaths a year in the UK: approximately 1 in five deaths in men and one in six deaths in women. Although death rates from CHD have been falling rapidly in the UK since the late 1970s, they are still among the highest in Western Europe. There is considerable variation in death rates from CHD in the UK: death rates are higher in Scotland than in the south of England, as shown in Figure 1, and this is typical of all age groups and both sexes. Also death rates are higher in manual workers than non-manual workers and are particularly high among Indian and Pakistani men.
Unsurprisingly, the burden of morbidity from this disease is also very high. There are estimated to be about 1.5 million men living in the UK who have CHD (either angina or a myocardial infarction), and about 1.1 million women. Data from the 2003 health survey for England suggest the prevalence of CHD in England is about 7.4% in men and 4.5% in women. Prevalence rates increase with age so that around one in four men and one in five women aged 75 and over are living with CHD. Aggregated data from Quality and Outcomes Framework (QOF) returns suggest that 3.6% of all GP registrations in the UK are known to have some form of CHD. The economic burden of all this disease is enormous: estimated costs to the UK economy are £7.9 billion per annum, of which 45% is taken up by health-care costs, 40% in loss of productivity, and 16% in informal care costs.
Primary care management A GP must be able to manage primary contact with patients who have a cardiovascular problem; co-ordinate care with other primary care health professionals, cardiologists and other appropriate specialists, leading to effective and appropriate acute and chronic disease management including prevention; promote cardiovascular wellbeing by applying health promotion and disease prevention strategies appropriately; and, describe strategies for early detection of cardiovascular problems that may already be present but have not yet produced symptoms.
Knowledge base
Person-centred care
Contextual aspects
Attitudinal aspects
Scientific aspects
Psychomotor skills
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Preventive measures |
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The need for preventive measures is self evident from the statistics. There are two main strategies for prevention: primary and secondary prevention.
Primary prevention
Primary prevention aims to stop CHD developing in a population. There are several ways in which this can be achieved. Population strategies influence the factors that increase CHD in an entire population. A good example of a population strategy is the move to ban smoking in public places recently introduced in England. GPs can use population strategies too, for example by displaying health education posters or literature in places that all their patients have access to, such as the waiting room or practice leaflet.
High-risk strategies identify individuals at high risk of disease and attempt to decrease the risk in those patients. For cardiovascular disease, high-risk patients are those with diabetes mellitus (DM) and also apparently healthy individuals who are at high risk due to the combination of risk factors that they have. Risk can be estimated using tables. An opportunistic strategy targeting high risk individuals is preferable to screening a whole population, both in terms of health gain and cost-effectiveness. In primary care, opportunistically screen all adults over 40 years in age for CHD risk, even if they have no personal or family history of CHD or diabetes. Total CHD risk can then be estimated using charts (Figure 2). If cardiovascular risk over 10 years is 20% or more, intervention with lifestyle and/or drug measures to decrease risk is justified.
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Secondary prevention
Secondary prevention aims to stop progression of symptomatic CHD. Of patients who die from myocardial infarct, nearly half (46%) are already known to have CHD. There is strong evidence that targeting patients with CHD for risk-factor modification is effective in decreasing the risk of recurrent CHD.
There are many risk factors for heart disease. Some are modifiable and some are not (Table 1). Secondary prevention strategies concentrate on modifying the risk factors that can be changed to have maximum effect on disease mitigation. (GMS Contract Quality and Outcomes Framework targets for CHD prevention can be found in Table 2)
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Patient self-help |
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Whether for primary or secondary prevention, provision of information to patients can enable them to self-care and follow a more healthy lifestyle. Box 1 lists some useful information resources for patients.
| Box 1. Self-help information for patients British Heart Foundation 0845 0708 070 Website: www.bhf.org.uk Hearts for Life Website: www.heartsforlife.co.uk Diabetes UK 0845 120 2960 Website: www.diabetes.org.uk Blood Pressure Association 020 8772 4994 Website: www.bpassoc.org.uk Action on smoking and health (ASH) Website: www.ash.org.uk NHS Smoking helpline 0800 169 0 169; pregnancy smoking helpline 0800 169 9 169 Website: www.givingupsmoking.co.uk Quit Helpline 0800 00 22 00 Website: www.quit.org.uk
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Modification of risk factors |
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The vast majority of both primary and secondary CHD prevention work occurs in nurse-led clinics – for example, cardiovascular disease, hypertension or diabetic clinics. GPs should be involved with organization of care, help develop the structure of reviews, be available to manage problems that are found during the course of reviews and manage medication. Use of templates ensures that patients receive comprehensive care and that all the data required for the quality and outcomes framework is recorded.
Smoking
No patient who has had any sort of episode of CHD should be smoking. The GMS contract encourages all GPs to gather data on smoking and offer appropriate advice (Table 3). Advice from a GP about smoking cessation results in 2% of smokers stopping – 5% if advice is repeated. Strong motivation, often secondary to an episode of poor health directly related to smoking such as myocardial infarct, is a vital factor. A strategy for management of smokers in the surgery is outlined in Figure 3. Drug therapy increases smoking cessation rates by 1
to 2 times, whether nicotine replacement, bupropion or varenicline is used. In many areas "stopping smoking" services are provided by Primary Care Organizations. These programmes vary from area to area but generally consist of group education, counselling and support, plus possibly some individual support, in combination with nicotine replacement, bupropion or varenicline therapy. However, there is very little evidence that this type of support increases smoking cessation rates over and above rates achieved using medication alone.
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Hypertension
A major risk factor for CHD, hypertension is under-diagnosed and under-managed in the UK. Raised blood pressure (BP) is symptomless until it causes organ damage. About 50% of the population aged 65–74 yrs have raised BP. Management aims to detect and treat it before damage occurs.
Blood pressure is a continuous variable – the higher the BP the greater the risk of CHD. There is no figure above which hypertension can be diagnosed definitively although currently treatment is considered at once blood pressure exceeds 140/90 mmHg. Aims of treatment are to lower blood pressure to below 140/85 mmHg (and below 130/80 mmHg if the patient is diabetic). Benefits of treatment remain in patients up to 85 years of age – and probably beyond. Patients over 80 should be offered the same treatment as young patients, taking into account any co-morbidity and existing drug-use.
Regular review of patients with hypertension is essential. Once raised BP is controlled, routine review of BP can be undertaken by properly trained practice nurses but annual review of medication should be undertaken by a GP and the GP must review if the BP is not controlled.
All hypertensive patients should be offered advice about non-pharmacological treatment. Measures include decreasing salt intake, decreasing alcohol intake, and increasing exercise, as well as losing weight. Such measures undoubtedly help with lowering blood pressure but are usually not enough by themselves: pharmacological intervention is virtually always necessary. The two major guideline-producing bodies in the UK have now combined to produce consensus guidelines for the treatment of hypertension in primary care (Figure 4).
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Hyperlipidaemia
Average cholesterol level in a population is associated with CHD risk and dependent on diet but, on an individual level, it is a much poorer predictor and only 42% of those who develop CHD have raised cholesterol. However, lowering cholesterol is of proven benefit in primary and secondary prevention of CHD.
Blood cholesterol concentration is not steady over time. Twenty-five per cent of raised serum cholesterol tests are normal on repeat testing. Therefore, it is important to check at least two samples at different times before diagnosing that a patient has high cholesterol. Before initiating treatment or if screening for familial dyslipidaemia, take fasting samples, and check triglyceride levels as well. For screening and routine follow up, take non-fasting samples, testing total blood cholesterol and total cholesterol:HDL ratio. All those who have proven CHD should have cholesterol levels checked annually.
All patients should be offered non-pharmacological advice on lifestyle factors that influence lipid levels. Generally, dietary fat should be kept to 30% or less of total energy intake. Advise patients to eat a low cholesterol diet, increase fruit and vegetables and decrease salt intake. In patients with a body mass index (BMI) of 30 kg/m2 or more, weight loss of 10 kg results in a 7% decrease in LDL and 13% increase in HDL cholesterol. Increase in physical activity also enhances cholesterol-lowering effects of diet and weight loss. At the same time, give general advice about lowering cardiovascular risk, for example smoking cessation.
When considering risk factors and cardiovascular risk, it is important to use a person-centred approach. Although risk factors all have different treatments, it is essential not to treat each risk factor in isolation but look at the overall risk for each patient. Decisions on whether pharmacological measures to reduce cholesterol should be instituted for primary prevention of CHD are made on the basis of this overall risk. For example, it is appropriate to treat a fit 35-year-old lady with a total cholesterol of 6, who does not smoke and has normal blood pressure, with diet as her overall risk of cardiovascular disease is acceptably low. A 70-year-old diabetic smoker with the same cholesterol has a much higher risk of cardiovascular events due to his combination of risk factors and thus should be treated with a statin to reduce that risk to a more acceptable level. The absolute level of risk deemed acceptable is debatable and determined by both benefit and risk to the patient from treatment, and cost to society. Currently, a 20% or greater risk of a cardiovascular event in the next 10 years is the level of risk that warrants active intervention with statins.
If 10 year cardiovascular disease risk is 20% or more, initiate statin therapy if total cholesterol is more than 4 mmol/l or LDL cholesterol is more than 2 mmol/l. Reducing cholesterol reduces all cause mortality by 22% and reduces CHD events by 31%. If a patient is diabetic, initiate statin treatment if the patient is 40 years of age or older, or is aged 18–39 years but has one or more other cardiovascular risk factors, such as retinopathy or family history of premature CHD.
All patients with proven CHD benefit from lowering total cholesterol and LDL cholesterol, irrespective of their initial cholesterol. A decrease in total cholesterol and LDL by 25–35% using statin therapy reduces CHD mortality by 25–35%. Aim to lower total cholesterol by 25% or to less than 4 mmol/l – whichever is the lower value, or to lower LDL cholesterol by 30% or to less than 2.0 mmol/l – whichever is the lower value. LDL cholesterol levels are most important in lowering cardiovascular risk. Rarely patients are intolerant of statins. In that case, fibrates should be used instead to lower cholesterol.
Diabetes mellitus
DM is a major risk factor for coronary heart disease. Diabetics are at 2–5 times increased risk of myocardial infarction, compared with the general population. Furthermore, diabetics with the metabolic syndrome, consisting of insulin resistance, dyslipidaemia, and central obesity, have an even higher risk of all types of cardiovascular disease, and need to be treated aggressively.
Blood glucose levels should be kept as low as possible, with a target HbA1c of less than 7.5%. For those diabetics with higher risk of arterial disease due to other risk factors HbA1c should be kept less than 6.5%. BP should be lowered if it is elevated above 140/85 mmHg with a target figure of 130/80 mmHg and hyperlipidaemia should be treated. Give aspirin at a dose of 75 mg per day to all diabetics:
- with evidence of vascular disease, and/or
- if the patient is over 50 years of age, and/or
- if the patient has a history of DM for more than 10 years, and/or
- if the patient is receiving treatment for hypertension.
- if the patient is over 50 years of age, and/or
Diet and obesity
Obesity is one of the most important preventable diseases in the UK. The best measure of obesity is BMI. The new GMS Contract Quality and Outcomes Framework rewards practices for keeping a register of patients with BMI of more than 30 kg/m2 (Obesity 1). Waist circumference is an alternative, indirect, measurement of body fat that reflects the intra-abdominal fat mass. It is strongly correlated with CHD risk, DM, hyperlipidaemia, and raised BP. It is measured halfway between the superior iliac crest and the rib cage in the mid-axillary line (Table 2). Although obesity, in particular central obesity, is correlated with an increased risk of many vascular risk factors (hypertension, DM, hyperlipidaemia), it also appears to be an independent risk factor.
Treatment of obesity is a complex issue. In general, patients should aim for a BMI of not more than 25 kg/m2. This can be achieved by a combination of decreased energy intake, and increased energy expenditure (more exercise) and may necessitate drug therapy (with drugs that reduce fat absorption from the gut such as Orlistat, or central appetite suppressants such as sibutramine or rimonabant) and even surgery.
Diets rich in omega-6 and omega-3 fatty acids (found in oily fish, vegetables and nuts) are beneficial for secondary prevention of CHD. Their effect is through reduction in risk of thrombosis. Consider providing or suggesting over-the-counter supplements if a patient has suffered a myocardial infarct less than three months previously and has dietary deficiency.
Exercise
Exercise is beneficial to many aspects of health, in particular cardiovascular health. Regular physical activity lowers the risk of CHD and physically inactive people have about twice the risk of CHD of active people. Physically inactive people also have a higher risk of DM through increased insulin sensitivity.
It is recommended that adults take at least 30 min of moderate intensity exercise (for example, brisk walking) on at least five days every week, and that children take at least an hour of moderate intensity activity every day. Regular exercise is a useful treatment for:
- Obesity
- Hypertension – exercise can result in a10 mmHg drop of systolic and diastolic BP and can also delay onset of hypertension
- Hypercholesterolaemia – exercise raises HDL, and lowers LDL cholesterol
- Myocardial infarct – post-infarct cardiac rehabilitation programmes increase exercise tolerance and improve quality of life of patients
- DM – exercise improves insulin sensitivity and favourably affects other risk factors for DM including obesity, HDL/LDL cholesterol ratio and BP
Alcohol
Recommended safe levels of alcohol consumption are 21 units per week for men and 14 units per week for women. Moderate consumption of alcohol (one to three units per day) is known to decrease the risk of angina and myocardial infarction. Excess alcohol consumption is linked with hypertension, DM, obesity, and cardiomyopathy.
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Use of aspirin as a preventative measure |
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Aspirin is used for primary and secondary prevention of CHD. For primary prevention, advise patients over 50 years of age who have a 10 year cardiovascular disease risk of 20% or more to take 75 mg of aspirin each day. This results in a 20% decrease in non-fatal myocardial infarction at a cost of a small increase in risk of bleeding. The benefit increases with any increase in cardiac risk. For patients with diabetes mellitus who do not have heart disease, recommend 75 mg of aspirin per day from the patient's 50th birthday or if the patient is younger but has had diabetes for more than 10 years.
Patients with hypertension should start aspirin 75 mg daily once their blood pressure is controlled to less than 150/90 mmHg, if they are 50 years of age or older, diabetic, have target organ damage (left ventricular hypertrophy, renal impairment, retinal vein occlusion, transient ischaemic attack or stroke, myocardial infarct or angina) or have 10 year cardiovascular risk of more than 20%.
Patients with past history of myocardial infarct or angina should take aspirin 75–150 mg daily as a secondary prevention measure (see below). In addition, patients who do not have a history of heart disease or hypertension but do have a history of stroke or peripheral vascular disease, should also be taking aspirin as a secondary prevention measure.
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Drug treatment used for secondary prevention of CHD |
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After a myocardial infarction, several drugs have been proven to reduce mortality. Unless contraindicated, all patients ho have suffered a myocardial infarction should be started on an oral β-blocker (such as atenolol) soon after myocardinal infarction. This should be continued indefinitely. Treatment with β-blockers is estimated to prevent 12 deaths/1000 treated/year.
ACE inhibitors decrease myocardial work and reduce deaths within one month after myocardinal infarction by 5/1000 treated. Survival advantage is sustained after a year, even if treatment is not continued long-term. Effects are greater for patients with heart failure at presentation. Treatment with long-term ACE inhibitors results in lowered mortality for all patients.
Starting aspirin within 24 h of myocardinal infarction prevents 80 vascular events over the next 2 years/1000 patients treated. Unless contraindicated, this should continue life long. Usual practice is to give 75 mg daily. Occasionally (for example if there is a left ventricular aneurysm, or the patient is in atrial fibrillation) anticoagulation is indicated instead. All patients with angina should also be taking aspirin.
Cholesterol-lowering is beneficial for all patients with proven CHD, irrespective of initial cholesterol levels. This is usually achieved using a statin.
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Concordance and CHD prevention |
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Concordance is a process of prescribing and medicine taking based on partnership. Patient concordance (or rather lack of it) is a major challenge in general practice and particularly for drugs used for prevention. For drugs to be optimally effective they should be taken as directed by the prescriber. Concordance sufficient to attain therapeutic objectives occurs about half the time – 1 in 6 patients take medication exactly as directed; 1 in 3 take medication as directed 80–90% of the time; 1 in 3 take medication 40–80% of the time; the remaining 16–17% take medication as directed less than 40% of the time. A further 20% prescriptions are never "cashed". This failure to take preventive medication has serious consequences. For example, failure to take antihypertensive medication has been shown to decrease the potential reduction of stroke by 30–50%. It also wastes precious resources. Effects of non-concordance may be masked by "White-coat concordance", a phenomenon in which 90% of patients take regular medication as directed for a period before a check up.
There are many causes of non-concordance – patient beliefs (such as how natural a medicine is seen to be), lifestyle choices (for instance decisions not to take drugs due to side effects or inconvenience of multiple dose regimens), lack of understanding of the condition and/or way to take the medication, practical restrictions such as forgetfulness or inability to open containers, and problems with interaction between doctor and patient.
Improving concordance
Seventy per cent of patients want to be more involved in decisions about treatment. Doctors underestimate the degree to which they instruct and overestimate the degree to which they consult and elicit their patients’ views. The doctor's task is, by negotiation, to help patients choose the best way to manage their problem. Patients are more likely to be motivated to take medicines as prescribed when they understand and accept the diagnosis, agree with the treatment proposed and have had their concerns about the medicines specifically and seriously addressed. Community pharmacists also have a role in improving concordance, including their recently increased role in undertaking community medication reviews.
Ways to improve concordance
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Conclusions |
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GPs have a vital role in the prevention of CHD. This involves the following:
- Identification of patients who would benefit from primary prevention through opportunistic risk factor screening or routine checks (e.g. new patient checks). Quality and outcome framework points (and thus payments) are available for doing this
- Ensuring patients who have proven atherosclerotic disease have ongoing follow-up (through disease registers, routine recall and follow up by the practice, and/or secondary care services and monitoring of drug prescriptions). Points gained for meeting secondary prevention targets contained within the QOF reward practices for this
- Promoting lifestyle modification in at risk patients
- Ensuring current best care guidelines are followed and treatment regimens are updated as policies change
- Checking the process through audit
Although there has been undoubted progress in reducing morbidity and mortality from CHD in recent years, there is room for further improvement.
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References |
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