How low should cholesterol levels be?

Current situation 

  • A large audit showed recently that only 50 per cent of patients with cardiovascular disease (CVD) had cholesterol below 5mmol/l and of those CVD patients receiving a statin, two thirds reached target (Br J Cardiol 2006; 13: 145-53).
  • Patients with stroke and peripheral vascular disease are still suboptimally managed compared with those with CHD.
  • The costs of lipid-regulating drugs in England was £600 million over the past year. This represented 8 per cent of the total primary care drug spend.

What is the evidence?

  • Lowering cholesterol levels with statins has been shown to reduce CHD event rates in both primary and secondary prevention trials (for example 4S, Cholesterol and Recurrent Events trial, WOSCOP).
  • The Heart Protection Study demonstrated that simvastatin 40mg is beneficial in patients with diabetes, stroke or peripheral vascular disease up to the age of 85 years, irrespective of baseline LDL-cholesterol level (Lancet 2002; 360: 7-22).
  • Reducing LDL-cholesterol to very low levels carries no safety concerns, a sub-study of the Prove-It trial concluded (J Am Coll Cardiol 2005; 46: 1,411-6).
  • Lipid levels are strongly associated with ischaemic stroke occurring in healthy women (Neurology 2007; 68: 556-62).
  • Patients with acute MI who take their statins as prescribed are significantly more likely to survive for two to three years than those with low adherence (J Am Med Assoc 2007; 297: 177-86).
  • Follow-up results of the WOSCOP study have demonstrated that men with hypercholesterolaemia and no history of MI have a significant 10-year reduction in coronary events if they are treated with pravastatin (N Engl J Med 2007; 357: 1,477-86).

Implications for practice

  • A study of people aged between 45 and 84 years showed that only 40 per cent of those people taking lipid-lowering treatment actually had cholesterol levels below target. Also, the majority of those at low risk of CVD were treated compared with about half of those at high risk of CVD (Circulation 2006; 113: 647-56).

Guidelines

  • The Joint British Societies guidelines state that patients aged over 40 should have their cardiovascular risk assessed. Their targets have now moved to 4mmol/l and 2mmol/l, respectively (Heart 2005; 91(suppl V): 1-52). However, the DoH guidelines have stated that total cholesterol <5mmol/l and LDL <3mmol/l are the targets to be sought.
  • The NICE guidance on statins for the prevention of cardiovascular events was produced in January 2006. It states that statin treatment is recommended for adults with a 20 per cent or greater 10-year risk of developing CVD.

Dr Newson is a GP in the West Midlands and author of 'Hot Topics for MRCGP and General Practitioners' PasTest, 2006.

Key points

  • Statin therapy reduces CHD events.
  • More patients should be taking statins.
  • Target levels are even lower.
  • Long-term benefits for primary prevention.

Useful websites

NICE www.nice.org.uk

BHS www.hyp.ac.uk.

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