Hypercholesterolemia

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Hypercholesterolemia is "a condition with abnormally high levels of cholesterol in the blood. It is defined as a cholesterol value exceeding the 95th percentile for the population."[1] It should be differentiated from dyslipidemia, where the total cholesterol may not be abnormally high, but the ratios of lipid components are in an unhealthy reange.

Treatment

A meta-analysis estimated that after 5 to 7 years of treatment with statins, the relative risk reduction of coronary heart disease events is decreased by approximately 30%[2][3]. More recently, a meta-analysis reported an almost identical relative risk reduction of 29.2% in low risk patients treated for 4.3 years [4]. A relative risk reduction of 19% in coronary mortality was found in a meta-analysis of patients at all levels of risk.[5]

Clinical practice guidelines

Various clinical practice guidelines have addressed the treatment of hypercholesterolemia.

Clinical practice guidelines by the National Institute for Health and Clinical Excellence in 2008 recommend treatment if the estimated 10 year risk of cardiovascular disease is at least 20%.[6][7]

The American College of Physicians in 2004 addressed hypercholesterolemia in patients with diabetes [8]. Their recommendations are:

  • Recommendation 1: Lipid-lowering therapy should be used for secondary prevention of cardiovascular mortality and morbidity for all patients (both men and women) with known coronary artery disease and type 2 diabetes.
  • Recommendation 2: Statins should be used for primary prevention against macrovascular complications in patients (both men and women) with type 2 diabetes and other cardiovascular risk factors.
  • Recommendation 3: Once lipid-lowering therapy is initiated, patients with type 2 diabetes mellitus should be taking at least moderate doses of a statin (the accompanying evidence report states "simvastatin, 40 mg/d; pravastatin, 40 mg/d; lovastatin, 40 mg/d; atorvastatin, 20 mg/d; or an equivalent dose of another statin")[9].
  • Recommendation 4: For those patients with type 2 diabetes who are taking statins, routine monitoring of liver function tests or muscle enzymes is not recommended except in specific circumstances.

The National Cholesterol Education Program revised their guidelines in 2004 to include goal LDL values.[10]; however, their 2004 revisions have been criticized for use of nonrandomized, observational data.[11] A decision analysis found that treating to targets is not efficient.[12]

Primary prevention

One meta-analysis found that overall mortality is insignificantly reduced from 6.6% over 4.3 years to 6.1% in patients without prior cardiovascular disease (Number needed to treat, although statistically insignificant, is estimated to be 200).[4]

A second meta-analysis reported that statins can significantly help in the primary prevention of coronary heart disease among patients at risk.[13]

Treating based on risk factors is probably better than treating to a specific target LDL cholesterol.[12]

Combination treatment

It is not clear that combination therapy is better than high dose hydroxymethylglutaryl-coenzyme A reductase inhibitors.[14] If treatment with a hydroxymethylglutaryl-coenzyme A reductase inhibitor does not achieve a desirable cholesterol, other drugs that have been studied include eicosapentaenoic acid which is a metabolite of fish oil.[15] Ezetimibe, a cholesterol-absorption inhibitor, was not clearly beneficial in a study of diabetes mellitus type 2[16] and a study of mixed primary prevention and secondary prevention[17]. Niacin has been studied with improvements in the LDL and HDL[18] with uncertain[19] effects on carotid intima-media thickness.

Secondary prevention

Clinical practice guidelines by the National Institute for Health and Clinical Excellence recommend treatment goal of <4 mmol/l (77 mg/dl)or a low density lipoprotein cholesterol concentration of <2 mmol/l (154 mg/dl).[6][7]

Combination treatment

If treatment with a hydroxymethylglutaryl-coenzyme A reductase inhibitor does not achieve a desirable cholesterol, other drugs that may be added for additional benefit include niacin[20][21][19] and fish oil. Ezetimibe, a cholesterol-absorption inhibitor, was not clearly beneficial in a study of diabetes mellitus type 2[16] and a study of mixed primary prevention and secondary prevention[17].

Diabetic patients

For more information, see: Diabetes_mellitus_type_2#Hypercholesterolemia.


Whether diabetes is an equivalent risk factor to having an existing myocardial infarction is debated.[22]

Statin therapy prevents major vascular events in about 1 of every 24 patients with diabetes who use the treatment for 5 years if they are similar to the patients in the meta-analysis by Kearney et al (Number needed to treat is 24).[23]

Treating to a goal of LDL-C < 70 mg/dl and systolic blood pressure to < 115 mm Hg may cause regression of carotid intima-media thickness in a randomized controlled trial.[24]

New research

Preliminary research suggests possible benefit from artichoke leaf.[25]

References

  1. ↑ Anonymous. Hypercholesterolemia. National Library of Medicine. Retrieved on 2008-01-18.
  2. ↑ Pignone MP, Phillips CJ, Atkins D, Teutsch SM, Mulrow CD, Lohr KN (2001). "Screening and treating adults for lipid disorders". American Journal of Preventive Medicine 20 (3 Suppl): 77–89. PMID 11306236. [e]
  3. ↑ Screening for Lipid Disorders: Recommendations and Rationale. Retrieved on 2007-10-17.
  4. ↑ 4.0 4.1 Thavendiranathan P, Bagai A, Brookhart M, Choudhry N (2006). "Primary prevention of cardiovascular diseases with statin therapy: a meta-analysis of randomized controlled trials". Arch Intern Med 166 (21): 2307-13. DOI:10.1001/archinte.166.21.2307. PMID 17130382. Research Blogging. Cite error: Invalid <ref> tag; name "pmid17130382" defined multiple times with different content
  5. ↑ Baigent C, Keech A, Kearney PM, et al (2005). "Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins". Lancet 366 (9493): 1267-78. DOI:10.1016/S0140-6736(05)67394-1. PMID 16214597. Research Blogging.
  6. ↑ 6.0 6.1 Cooper A, O'Flynn N (2008). "Risk assessment and lipid modification for primary and secondary prevention of cardiovascular disease: summary of NICE guidance". BMJ. PMID 18511800. PMC 2405875. [e]
  7. ↑ 7.0 7.1 Anonymous (2008). Lipid modification. National Institute for Health and Clinical Excellence. Retrieved on 2008-08-26.
  8. ↑ Snow V, Aronson M, Hornbake E, Mottur-Pilson C, Weiss K (2004). "Lipid control in the management of type 2 diabetes mellitus: a clinical practice guideline from the American College of Physicians". Ann Intern Med 140 (8): 644-9. PMID 15096336.
  9. ↑ Vijan S, Hayward RA (2004). "Pharmacologic lipid-lowering therapy in type 2 diabetes mellitus: background paper for the American College of Physicians". Ann. Intern. Med. 140 (8): 650-8. PMID 15096337. [e]
  10. ↑ Grundy SM, Cleeman JI, Merz CN, Brewer HB, Clark LT, Hunninghake DB, Pasternak RC, Smith SC, Stone NJ (2004). "Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III Guidelines". J. Am. Coll. Cardiol. 44 (3): 720-32. DOI:10.1016/j.jacc.2004.07.001. PMID 15358046. Research Blogging.
  11. ↑ Hayward RA, Hofer TP, Vijan S (2006). "Narrative review: lack of evidence for recommended low-density lipoprotein treatment targets: a solvable problem". Ann. Intern. Med. 145 (7): 520-30. PMID 17015870. [e]
  12. ↑ 12.0 12.1 Hayward RA, Krumholz HM, Zulman DM, Timbie JW, Vijan S (2010). "Optimizing statin treatment for primary prevention of coronary artery disease.". Ann Intern Med 152 (2): 69-77. DOI:10.1059/0003-4819-152-2-201001190-00004. PMID 20083825. Research Blogging.
  13. ↑ Brugts JJ, Yetgin T, Hoeks SE, et al. (2009). "The benefits of statins in people without established cardiovascular disease but with cardiovascular risk factors: meta-analysis of randomised controlled trials". BMJ 338: b2376. PMID 19567909. [e]
  14. ↑ Sharma M, Ansari MT, Abou-Setta AM, Soares-Weiser K, Ooi TC, Sears M et al. (2009). "Systematic review: comparative effectiveness and harms of combination therapy and monotherapy for dyslipidemia.". Ann Intern Med 151 (9): 622-30. DOI:10.1059/0003-4819-151-9-200911030-00144. PMID 19884623. Research Blogging.
  15. ↑ Yokoyama M, Origasa H, Matsuzaki M, et al (March 2007). "Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis". Lancet 369 (9567): 1090–8. DOI:10.1016/S0140-6736(07)60527-3. PMID 17398308. Research Blogging.
  16. ↑ 16.0 16.1 Howard BV, Roman MJ, Devereux RB, et al (April 2008). "Effect of lower targets for blood pressure and LDL cholesterol on atherosclerosis in diabetes: the SANDS randomized trial". JAMA 299 (14): 1678–89. DOI:10.1001/jama.299.14.1678. PMID 18398080. Research Blogging.
  17. ↑ 17.0 17.1 Kastelein JJ, Akdim F, Stroes ES, et al (April 2008). "Simvastatin with or without ezetimibe in familial hypercholesterolemia". N. Engl. J. Med. 358 (14): 1431–43. DOI:10.1056/NEJMoa0800742. PMID 18376000. Research Blogging.
  18. ↑ McKenney JM, Jones PH, Bays HE, et al (June 2007). "Comparative effects on lipid levels of combination therapy with a statin and extended-release niacin or ezetimibe versus a statin alone (the COMPELL study)". Atherosclerosis 192 (2): 432–7. DOI:10.1016/j.atherosclerosis.2006.11.037. PMID 17239888. Research Blogging.
  19. ↑ 19.0 19.1 Taylor AJ, Sullenberger LE, Lee HJ, Lee JK, Grace KA (December 2004). "Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol (ARBITER) 2: a double-blind, placebo-controlled study of extended-release niacin on atherosclerosis progression in secondary prevention patients treated with statins". Circulation 110 (23): 3512–7. DOI:10.1161/01.CIR.0000148955.19792.8D. PMID 15537681. Research Blogging.
  20. ↑ Taylor AJ, Villines TC, Stanek EJ, Devine PJ, Griffen L, Miller M et al. (2009). "Extended-release niacin or ezetimibe and carotid intima-media thickness.". N Engl J Med 361 (22): 2113-22. DOI:10.1056/NEJMoa0907569. PMID 19915217. Research Blogging.
  21. ↑ Brown BG, Zhao XQ, Chait A, et al. (November 2001). "Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease". N. Engl. J. Med. 345 (22): 1583–92. PMID 11757504. [e]
  22. ↑ Bulugahapitiya U, Siyambalapitiya S, Sithole J, Idris I (February 2009). "Is diabetes a coronary risk equivalent? Systematic review and meta-analysis". Diabet. Med. 26 (2): 142–8. DOI:10.1111/j.1464-5491.2008.02640.x. PMID 19236616. Research Blogging.
  23. ↑ Kearney PM, Blackwell L, Collins R, et al (2008). "Efficacy of cholesterol-lowering therapy in 18,686 people with diabetes in 14 randomised trials of statins: a meta-analysis". Lancet 371 (9607): 117–25. DOI:10.1016/S0140-6736(08)60104-X. PMID 18191683. Research Blogging.
  24. ↑ Howard, B. V., Roman, M. J., Devereux, R. B., Fleg, J. L., Galloway, J. M., Henderson, J. A., et al. (2008). Effect of Lower Targets for Blood Pressure and LDL Cholesterol on Atherosclerosis in Diabetes: The SANDS Randomized Trial. JAMA, 299(14), 1678-1689. DOI:10.1001/jama.299.14.1678.
  25. ↑ Wider B, Pittler MH, Thompson-Coon J, Ernst E (2009). "Artichoke leaf extract for treating hypercholesterolaemia.". Cochrane Database Syst Rev (4): CD003335. DOI:10.1002/14651858.CD003335.pub2. PMID 19821306. Research Blogging.
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