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Lipid modification: cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease
  1. J Robson
  1. Dr John Robson, Centre for Health Sciences, Queen Mary’s School of Medicine and Dentistry, London E1 2AT, UK; j.robson{at}qmul.ac.uk

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The National Institute for Health and Clinical Excellence (NICE) guideline, Lipid modification: Cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease1 is a significant advance over earlier more fragmented approaches to cardiovascular risk. The guideline provides strategies for identification of patients at risk, suggests lipid modification in primary and secondary prevention and unifies treatment approaches to coronary heart disease, stroke and peripheral vascular disease. This guideline does not give recommendations for patients with underlying disorders that increase cardiovascular disease risk, but NICE guidance on diabetes, which includes lipid modification, has also just been published2 and NICE guidance on familial hypercholesterolaemia is due shortly.

A 20% cardiovascular disease (CVD) 10-year risk threshold for statin treatment was established by the technology appraisal on statins.3 This is considerably lower than the previously recommended National Service Framework threshold, which is equivalent to a 40% CVD risk. The new 20% CVD risk threshold increases the numbers of people targeted for further clinical assessment and possible statin treatment for primary prevention in England and Wales from around one million to over three million.4 The guideline endorses this threshold and sets out a strategy for the identification of people at high CVD risk and clarifies their management and treatment.

The guidance recommends a systematic strategy to identify people aged 40–74 years at high CVD risk to replace assessments currently undertaken opportunistically in primary care. Electronic records in general practice now contain a wealth of risk factor data including smoking, blood pressure, body mass index and cholesterol from which a prior estimate of CVD risk can be obtained. This estimate of CVD risk allows people to be ranked from highest to lowest in order of their risk. People can then be reviewed in order of clinical risk and priority, to discuss the need for a more formal, current and comprehensive assessment of CVD risk. This will provide the basis for a management plan that takes account of all modifiable risk factors—smoking, diet, physical activity and other lifestyle changes and the need for statins. Opportunistic assessment remains a component of everyday general practice and is not precluded, but this more systematic approach provides a rational, fair and effective way of targeting resources to those most likely to benefit.

The guideline recommends the Framingham 1991 equation as the current risk score of choice but reminds clinicians that Framingham overestimates risk in the UK population.5

Further research is recommended to establish, as soon as possible, how more recently developed UK scores such as ASSIGN and QRISK compare with Framingham in clinical datasets with the inclusion of social deprivation, ethnicity, family history and conditions such as chronic renal disease.6 7

The guidance goes to some lengths to point out that risk estimation, whatever the tool, is inexact, but that risk estimation is better than clinical judgment alone. The resulting risk score needs to be interpreted by the clinician, taking account of other potential risk factors. For example, there are people with risks just below the 20% threshold who have other factors not included in Framingham risk scores that may increase cardiovascular risk—for example, social deprivation, body mass index >40, South Asian ethnicity and a history of premature heart disease. The guideline advises clinicians to increase risk by 1.4 if the patient is a South Asian man and by 1.5 if one first-degree relative has premature coronary heart disease (CHD).

The guideline sets an ambitious goal for primary care that will require imaginative support particularly in deprived areas where the number of people identified will be considerably larger. The guideline emphasises the importance of communication with patients including the importance of conveying risk and possible management options. Risk should be conveyed as absolute risk as well as relative risk and in a variety of formats.

Appropriate communication and materials for ethnic minority groups, particularly where this is associated with social disadvantage, are especially important. Management of people aged over 75 presents a challenge as it is often complicated by an array of social and medical factors. However people now aged 65 years can expect to live on average to 85 years and there is good evidence of cardiovascular benefit from statins up to if not beyond 85 years.8

The recommendations for drug therapy have been based upon robust trial evidence of reductions in major cardiovascular end points. The guideline recommends a straightforward approach to primary prevention using a standard dose of simvastatin 40 mg.

At this dose, the guideline documents that statins have an excellent track record of safety.

No target has been set for primary prevention, as there are no trials that demonstrate additional cardiovascular benefit from higher intensity statins in this group of people.

Simvastatin 40 mg is recommended for the initiation of treatment in people with pre-existing CVD including people with angina, a previous myocardial infarction, stroke, transient ischaemic attack or peripheral vascular disease. The one exception to this approach is for people at highest risk with acute coronary syndrome. Higher intensity statins, simvastatin 80 mg and atorvastatin 80 mg, are cost-effective for initiation of treatment in people with acute coronary syndrome.

The Guideline Development Group considered the cardiovascular benefits of aiming to achieve a serum cholesterol below 4 mmol/l (or below low-density lipoprotein (LDL) 2 mmol/l) using statins. In a rigorous cost-effectiveness analysis only simvastatin 80 mg proved cost-effective in a strategy based upon titration to a higher intensity statin when the threshold levels of 4 mmol/l total cholesterol or 2 mmol/l LDL cholesterol were not achieved on the initial dose of simvastatin 40 mg in patients with known CVD.

Despite a reduction by half in death rates over the last 20 years, CVD remains the leading cause of death in England and Wales for both men and women. In 2005, CVD caused one in three deaths, accounting for 124 000 deaths; 39 000 of those who died were younger than 75. For every one fatality, there are at least two people who have a major non-fatal CVD event.9 Medical advice and treatment have made a major impact and account for around a quarter of the reduction in these CVD deaths. The task of the Guideline Development Group was to recommend lipid modification treatment to further improve these figures. However, the Guideline Development Group was convinced of the importance of multiple risk factor modification and that social change and legislation on smoking, diet, physical activity, transport and the built environment have a central role in risk factor modification and wellbeing and are the essential context for medical programmes.

REFERENCES

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Footnotes

  • Competing interests: The author is the chair of the NICE Guideline on Lipid Modification and the co-author of QRisk and of the Framingham score on EMIS computer system.

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