Dr Alan Begg discusses the new guideline on lipid modification, which will prioritise patients on the basis of their clinical history

The new guideline from NICE on Lipid modification,1 although eagerly awaited, is unlikely to lead to any significant change in current clinical practice within primary care. Despite its relevance to a GP’s work and the importance of the topic within the QOF process, there may be disappointment in some practices at the missed opportunity and the lack of anything new, while relief in others that little change is required.

Systematic approach

The NICE guideline recommends a systematic approach to risk screening for cardiovascular disease (CVD), prioritised on the basis of recorded risk factors (see Box 1). This is possibly at variance with the Department of Health’s plans for vascular checks, which aim to ‘manage appropriately’ the vascular risk of everyone in the population aged between 40 and 74 years.2 This systematic approach was suggested in the SIGN guideline on Lipids and the primary prevention of coronary heart disease3 published in 1999 and now superseded by the guideline on Risk estimation and the prevention of cardiovascular disease.4 The earlier SIGN guideline advocated targeting high priority groups such as smokers, patients with hypertension, or those with a positive family history for cardiovascular risk screening. The NICE guideline gives little guidance on which patients should be proactively targeted, stating only that an initial estimation of risk should be made before a formal assessment and that this should be made on the basis of risk factors already recorded in the primary care medical records.

Box 1: Pathway for identification of CVD risk

  • Systematically identify from primary care records those patients aged 40–74 years who may be at high risk
  • Exclude those with a previous history of CHD, angina, stroke or TIA, peripheral vascular disease, diabetes or a monogenic lipid disorder, who are already at high risk
  • Formally estimate risk using cardiovascular risk prediction charts for primary prevention
  • If 10-year risk ?20% (if <20% but near, consider other factors):
      • increase risk factor: ×1.4 if male with South Asian background; ×1.5 if one first-degree relative has premature CHD (age <55 years in male and <65 years in female); ×1.5–2.0 if more than one first-degree relative affected
      • consider socio-economic group
      • record BMI
      • consider co-morbidities that increase risk
      • discuss lifestyle changes
      • use clinical judgement to inform decision regarding lipid modification therapy
CVD=cardiovascular disease; CHD=coronary heart disease; TIA=transient ischaemic attack; BMI=body mass index

Full formal risk assessment

A full risk assessment should continue to be estimated using the Framingham 1991 10-year risk equations so the cardiovascular risk prediction charts published in the British National Formulary,5 which are based on this equation, can continue to be used. The problem with the Framingham risk scoring system is that it tends to overestimate risk in low risk groups in the UK and underestimate risk in higher risk subgroups, such as some ethnic groups and those with a strong family history of premature coronary heart disease (CHD).6 It is also not appropriate for use with patients who are already considered to be at high risk of CVD who have familial hypercholesterolaemia or diabetes.

Although an alternative risk assessment tool, QRISK, was considered by the guideline development group (GDG), it was decided that there had been insufficient evaluation to support its use in place of the Framingham system; also, practitioners are already familiar with the Framingham system, and used to making adjustments as required by various social groupings. The GDG called for further research into QRISK.6 Other assessment tools, such as ASSIGN, which is being piloted in Glasgow,7 and ETHRISK, a web-based tool,8 have also been developed. There is merit in the current NICE approach of not adopting a change in risk factor assessment tool until the current debate over competing risk scores is settled and it is known which is most appropriate for the UK population.

Definitions

The guideline recommends that the systematic strategy should be used to identify those patients aged 40–74 years who may be at high risk. When carrying out a full risk assessment using the cardiovascular risk prediction charts, users should be aware that they reflect the level of risk at ages 49, 59, and 69 years, respectively. From age 70 to 74 years the CVD risk, especially in men, is usually ?20% over 10 years so the charts will underestimate the true total CVD risk.5

The NICE guideline acknowledges that risk may be underestimated in patients who are already receiving treatment for hypertension or lipid modification. It also states that clinicians should use their judgement to decide on further treatment in patients whose risk measurement is below the 20% threshold.

The definition of a positive family history needs to be standardised across the UK because at present it can lead to confusion and consequent recording variations. The NICE guideline suggests that the estimated risk should be increased by a factor of 1.5 if there is a first-degree relative with a history of premature CHD, and between 1.5 and 2.0 if more than one first-degree relative has a history of premature CHD.1 This contrasts with previous advice from the Joint British Societies guideline on Prevention of cardiovascular disease in clinical practice, which suggested an increase of 1.3 in the risk level for patients with a family history of premature CVD.9

The definition of family history in the NICE guideline maintains the 10-year differential between males and females (<55 years in men, <65 years in females) but refers to CHD in line with Framingham, which was originally developed to reflect only the CHD risk. In contrast, ASSIGN uses age 60 years as the cut-off for premature CVD for both sexes.4

Lifestyle modification

Changing lifestyle and modifying social risk factors remains an important aspect of CVD prevention. The guidance provided in the NICE guideline on Lipid modification is in line with previous guidance but a major omission is a lack of advice on the reduction of salt intake.10 The ‘salt story’ is interesting as we have long been aware from epidemiological data that increased salt intake is associated with increased blood pressure and increased CVD events. Reducing salt in the diet will effectively lower blood pressure but we now have the evidence that a reduction in dietary salt and subsequent lowering of blood pressure can be translated into a reduction of the long-term risk of cardiovascular events.11

Statin therapy

The recommendation to choose a statin with a low acquisition cost is in line with previous NICE guidance.12 One of the surprising recommendations, however, is that pravastatin may be used if simvastatin is contraindicated or is likely to cause drug interactions. Although pravastatin has a significant evidence base for its use in preventing cardiovascular events in both primary and secondary prevention, its use is decreasing because it does not perform as well in preventing cardiovascular events when compared with a higher intensity statin.13 The reduced benefit associated with less cholesterol reduction is reflected in recent guidance from NICE, which accepted that there was sufficient evidence that the benefit of cholesterol-lowering drugs was related to the degree of cholesterol lowering.14

Higher intensity statin therapy

Confusion is possible over the recommendation in the NICE guideline that treatment for the secondary prevention of CVD should be initiated with simvastatin 40 mg. This contrasts with the recommendation that a higher intensity statin should be used for acute coronary syndrome. Higher intensity statin therapy is defined as a statin that provides greater cholesterol lowering than simvastatin 40 mg, such as simvastatin 80 mg.1 Presumably this applies to all patients with myocyte necrosis (ST and non-ST elevation myocardial infarction) as measured by biochemical markers such as troponin as well as the category referred to as unstable angina.

In line with the SIGN guideline on prevention of CVD,4 the NICE guideline does not recommend a target cholesterol level for primary prevention, with an ‘audit’ level of 5 mmol/l, in line with QOF recommendations, being endorsed for total cholesterol. For secondary prevention, NICE agrees with the JBS2 targets of <4 mmol/l and <2 mmol/l for total cholesterol and low-density lipoprotein (LDL) cholesterol, respectively, although we do not have convincing evidence from clinical trials that reaching these levels will give the maximum benefit in reducing clinical events.15

Tests and measurements

Measuring a full fasting lipid (especially triglycerides) profile before commencing treatment is good practice and will help to identify specific hyperlipidaemias, although it should be remembered that it is likely to be a calculated rather than measured LDL cholesterol that the laboratory will provide.

Practices should also note that liver function tests (LFTs) should be measured only before starting treatment and at 3 and 12 months after commencement, but the test should not be repeated unless it is clinically indicated. This may be at variance with the current approach to measuring LFTs as part of a routine annual review. The advice to measure creatine kinase only if symptomatic seems sensible and is welcome.1 However, advice that repeat lipid measurements are unnecessary for those started on a statin for primary prevention needs to be challenged, as regular checks are an important component of structured care, helping to monitor compliance and providing patients with encouragement to maintain lifestyle change.

Resources

The costing report accompanying the NICE guideline will be seen as a huge disappointment to GPs, with no allowance made for additional practice resources.16 For full implementation in England, the additional drug costs are calculated at nearly £110 million, although the net additional resource required is reduced to £50.4 million once a reduction is made for the benefit of CVD events avoided. The cost of carrying out systematic CVD risk screening, although estimated at £14.4 million, has not been included, as funding for this screening has been announced separately by the Department of Health and not all of this is likely to come to the primary care sector.16

Practices can deliver effective CVD prevention, but resources need to be available to cover the additional staff time and costs of running prevention clinics.

Conclusion

With the Department of Health formulating plans for a national screening programme for vascular disease, risk management is at an exciting crossroads. General practice needs to play an important, if not the lead, role in that process with this guideline being an essential component.

  1. National Institute for Health and Care Excellence. Lipid modification: cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease. Clinical Guideline 67. London: NICE, 2008.
  2. Department of Health. Putting prevention first — vascular checks: risk assessment and management. London: DH, 2008. www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_083822
  3. Scottish Intercollegiate Guidelines Network. Lipids and the primary prevention of coronary heart disease (SIGN 40). Edinburgh: SIGN, 1999.
  4. Scottish Intercollegiate Guidelines Network. Risk estimation and the prevention of cardiovascular disease (SIGN 97). A national clinical guideline. Edinburgh: SIGN, 2007.
  5. British National Formulary March 2008. London: BMJ Publishing Group Ltd, Royal Pharmaceutical Society, 2008.
  6. National Collaborating Centre for Primary Care. Lipid modification: cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease. Royal College of General Practitioners, 2008.
  7. Tandy S. Single cardiovascular risk tool needed for UK, 28th May 2008. www.healthcarerepublic.com/news/GP/812228/Single-cardiovascular-risk-tool-needed-UK/
  8. Brindle P, May M, Gill P et al. Primary prevention of cardiovascular disease: a web-based risk score for seven British black and minority ethnic groups. Heart 2006; 92 (11): 1595–1602.
  9. JBS 2: Joint British Societies’ guidelines on prevention of cardiovascular disease in clinical practice. Heart 2005; 91 (suppl 5): v1–52.
  10. Cappuccio F. Commentary: Controversies in NICE guidance on lipid modification for the prevention of cardiovascular disease. Br Med J 2008; 336 (7655): 1248–1249.
  11. Cook N, Cutler J, Obarzanek E et al. Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP). Br Med J 2007; 334 (7599): 885.
  12. National Institute for Health and Care Excellence. Statins for the prevention of cardiovascular events. NICE Technology Appraisal 94. London: NICE, 2006.
  13. Rouleau J. Improved outcome after acute coronary syndromes with an intensive versus standard lipid-lowering regimen: results from the Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis in Myocardial Infarction 22 (PROVE IT-TIMI 22) trial. Am J Med 2005; 118 Suppl 12A: 28–35.
  14. National Institute for Health and Care Excellence. Ezetimibe for the treatment of primary (heterozygous-familial and non-familial) hypercholesterolaemia. Technology Appraisal 132. London: NICE, 2007.
  15. Hayward R, Hofer T, Vijan S. Narrative review: lack of evidence for recommended low-density lipoprotein treatment targets: a solvable problem. Ann Intern Med 2006; 145 (7): 520–530.
  16. National Institute for Health and Care Excellence. Lipid modification: costing report—implementing NICE guidance. www.nice.org.uk/nicemedia/pdf/CG67costingreport.pdfG