1. Non-HDL Cholesterol and Apo B: To B or Not to B? 非高密度脂蛋白胆固醇与载脂蛋白 B ：选用载脂蛋白 B 吗？ Dr Richard Pang 3 November (Thursday) 2005 Symposium on Laboratory Medicine

2. To (measure apo) B Or NOT To (measure apo) B

3. Financial Constraints  LFT – ALT  RFT – Creatinine  TFT – TSH  Lipids (ASCVD) - ?

4. Heart Disease & Stroke Atherosclerosis Artery WallLipid MetabolismRisk FactorsGenetics PathologyLDL/VLDLHypertensionPopulation CytokinesHDLCoagulationEpidemiology OxidationBileDiabetesGenetic Markers HemodynamicsCholesterolObesityCandidate Genes VirusTriglyceridesImmune FactorsAnimal Models Lp(a)HomocystinuriaEnvironment A.J. Lusis, J.I. Rotter, R.S. Sparkes Karger, 1992, ISBN 3-8055-5558-X Monography in Human Genetics: Vol. 14, Molecular Genetics of Coronary Artery Disease.

5. Heart Attack! The commonest form of heart disease, CHD killed 3719 people in 2003 and accounted for 10.2% of the registered deaths… Source: Mortality statistics, 2003 (provisional data). Department of Health, Census and Statistics Department. The Government of Hong Kong Special Administrative Region.

8. Dyslipoproteinaemia Assessment of lipid related ASCVD risk in practice originally focused on total cholesterol. In fact, it is the lipoprotein and apolipoprotein particles that exert the beneficial or adverse effects. Measurement of the cholesterol carried within the particles particularly LDL and HDL serves as the commonly used default estimate of their concentrations

9. Courtesy of National Library of Medicine

10. The Lipoproteins VLDL=Very-low-density lipoprotein IDL=Intermediate-density lipoprotein LDL=Low-density lipoprotein HDL=High-density lipoprotein DensityParticle DiameterFlotation RateElectrophoretic Lipoprotein(kg/L)(nm)(Sf)Mobility Chylomicrons 400Origin VLDL0.95 – 1.00630 – 8060 – 400Pre-beta IDL1.006 – 1.01923 – 3520 – 60Broad beta LDL1.019 – 1.06318 – 250 – 20Beta HDL1.063 – 1.215 – 120 – 9Alpha

11.  Chylomicrons  LDL  VLDL  HDL  Free Fatty Acids

12. The Apolipoproteins HDL=High-density lipoproteinLCAT=Lecithin:cholesterol acyltransferase LPL=Lipoprotein lipaseHTGL=Hepatic triglyceride lipase VLDL=Very-low-density lipoproteinLDL=Low-density lipoprotein IDL=Intermediate-density lipoproteinLRP=LDL receptor-related protein Association with Apolipoprotein Main Functions CHD Risk Apo A-IStructural for HDL. Ligand for HDL binding. LCAT cofactor.Yes Apo A-IIStructural for HDL. Ligand for HDL binding. LCAT cofactor.No Modulator of LPL and HTGL activity (?) Apo A-IVLigand for HDL binding. LCAT activator.No Apo A-VIntracellular VLDL assembly. Down regulation of LPL (?)? Apo (a)Structural for Lp(a). Structural analogy with plasminogen.Yes Apo B-48Structural for chylomicrons.No Apo B-100Structural for VLDL, IDL and LDL. LDL receptor ligand.Yes Apo C-ILCAT and LPL activator.No Apo C-IILCAT and LPL activator.No Apo C-IIILPL inhibitor. Modulator of uptake of triglyceride-richNo lipoproteins by LRP. Apo DUnknown.No Apo ELigand for B/E receptors, LRP and apo E2 receptor.Phenotype, yes Apo FUnknown.No Apo HUnknown.No Apo JMembrane protection(?)No Apo MStructural for HDL. Transfer of cholesterol.?

13. Apolipoproteins PhospholipidCholesterol Triglycerides Cholesterol Esters Lipoprotein Structure Apo B-containing Lipoproteins

14. Segrest et al. Structure of apoB and LDL. J Lipid Res 2001 42:1346–1367. Apo B, which has a Mr of 550 kD, is the major protein found in LDL and is responsible for the cellular uptake of LDL particles from the plasma (Goldstein & Brown 1982).

15. Apo B-containing Lipoproteins  LDL  Triglyceride-rich lipoproteins  VLDL  IDL  Lp(a)

16. NCEPGUIDELINESNCEPGUIDELINES LIPID HYPOTHESIS ANIMAL DATA DATA DECREASED OVERALL MORTALITY 1O1O PREVENTION STUDIES 2O2O PREVENTION STUDIES REGRESSION STUDIES

17. The Full Report of NCEP ATP-III http://www.nhlbi.nih.gov Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (Adult Treatment Panel III) JAMA May 16 2001, 285(19) p2486-97

19. Should the goal of lipid therapy be based on LDL-C, apo B-100 or non-HDL-C?

20. Sueta et al. Am J Cardiol 1999; 83: 1303-1307 Source: http://www.lipidsonline.org/

21. LDL-C as primary target of therapy   Limitations of LDL-C in general   LDL particles can be heterogeneous in size,   the LDL particle number may be a better indicator of the atherogenic potential of the LDL fraction than is LDL–C concentration.   Limitations of LDL –C in patients with hypertriglyceridaemia

22. Friedewald Formula (Calculated LDL-C) LDL-C = TC –(TG/2.2 + HDL-C) Estimated value of VLDL-C from TG BUT does not apply to chylomicrons (non-fasting)

23. Friedewald Formula (Calculated LDL-C) Based on two assumptions  Fasting  Triglyceride <4.5 mmol/L IMPORTANT

27.  Chylomicrons  LDL  VLDL  HDL TC = 31.5 TG = 4.3 HDL-C = 0.52 LDL-C = 29.0 (by calculation) LDL-C = 5.0 (by direct method) Apo A1 = <0.25 Apo B = 2.77 99CA074094 Cholestasis & Jaundice  Lp-X?  Free fatty acids

28. In many cases of fasting hypertriglyceridaemia common in diabetes  The clinician has no reliable estimate (usually an underestimate) of the LDL cholesterol by calculation  No objective index of lipid-associated CHD risk unless the LDL cholesterol is available (by labour intensive ultracentrifugation)  Significant bias (usually an overestimate) in the direct method

29.  Chylomicrons  LDL  VLDL  HDL  Free Fatty Acids TC = 5.9 TG = 14.3 LDL-C = 2.2 (by direct method) HDL-C = 0.71 Apo A1 = 0.93HbA1 = 11.2 Apo B = 1.10Glucose = 14.2 01C9214160 Poor glycaemic control 

30. To (measure apo) B Or NOT To (measure apo) B?

31. All that remains is for its reliability as a predictor of CHD risk that may be superior to LDL-C?

32. Relative risk  Much emphasis was placed on estimates of relative risk for CHD accompanying different lipoprotein fractions  Lipidologists have championed one fraction or another as the best predictor of CHD  LDL cholesterol  HDL cholesterol  Total cholesterol/HDL cholesterol  Small LDL particles  Remnant lipoproteins  Total apolipoprotein B  Lipoprotein(a)  Non-HDL cholesterol

33. Predictive Power of Lipoproteins  Total Cholesterol: Strong independent relation  LDL Cholesterol: widely accepted as independent risk factor  Reduced levels of HDL cholesterol: independently predict CHD incidence  High triglyceride levels carry independent predictive power has been less robust

34. Total apo B Signifies atherogenic potential and a strong predictor of CHD risk Sniderman AD. Counterpoint: To (measure apo) B or not to (measure apo) B: a critique of modern medical decision-making. Clin Chem 1997; 43: 1310-1314

36. Apo B as a better treatment index than LDL-C ? In general, statins produce closely similar percent reductions in concentrations of LDL-C and apo B, and therefore the reasons why apo B is a better index than LDL-C to assess adequacy of statin therapy may not be immediately obvious. However, in patients with small dense LDL, by definition, LDL particle number will be higher than LDL-C. Thus, on-treatment LDL-C concentration will give an inaccurate impression of the extent to which atherogenic particle number has been reduced, and treatment guided by this value could result in undertreatment.

38. Sniderman et al. Apolipoproteins versus lipids as indices of coronary risk and as targets for statin treatment. Lancet 2003; 361: 777–80

39. Practical Issue What if the laboratory does not measure apo B?

40. Current Methodologies  Rate immunonephlometric assays (INA)  Immunoturbidometric assays (ITA)  Enzyme-linked immunosorbent assays (ELISA) International Reference Material SP3-07 Relatively expensive

41. Non-HDL cholesterol and apolipoprotein B in the dyslipidemic classification of type 2 diabetic patients - Epidemiology/Health Services/Psychosocial Research - high density lipoprotein CONCLUSIONS: Non-HDL cholesterol and apoB are equivalent risk markers in hypertriglyceridemic patients, but apoB identifies additional patients with high-risk dyslipidemic phenotypes in normotriglyceridemic type 2 diabetic patients… Wagner et al. Diabetes Care 2003; 26: 2048-51.

42. To (measure apo) B Or NOT To (measure apo) B? Apo B vs Non-HDL cholesterol

43.  Because there is one apo B molecule per lipoprotein particle  Total apo B concentrations are a measure of total particle number of the “atherogenic” lipoproteins  HDL is a “good” cholesterol. Non-HDL cholesterol provides the cholesterol content of all the atherogenic lipoproteins  Total apo B was acknowledged (NCEP ATP III) as an alternative to non-HDL cholesterol but non-HDL cholesterol was highlighted because of wide availability and reliability of estimation

44. Non-HDL Cholesterol: A Logical Extension of the Priority Given to LDL Cholesterol?

46. Pang et al. Plasma lipid, lipoprotein and apolipoprotein levels in a random population sample of 2875 Hong Kong Chinese adults and their implications (NCEP ATP-III, 2001 guidelines) on cardiovascular risk assessment. Atherosclerosis 2005 (in press). Overall 39% Men 29% Women

47. Non-HDL Cholesterol into the Spotlight  Just a simple calculation  Easily available with every lipid profile  Eliminating any additional costs  Circumvents the measurement of triglycerides  Patient does not require in the fasting state (?!)  Avoids the potential inaccuracy of calculated LDL cholesterol

48. Medline Search YearNon-HDLTitle 199780 199882 199961 2000101 2001 NCEP ATP-III 143 2002185 20032912 2004 2005 (~October ) 39301511

50. The advantages of using Non-HDL cholesterol in the diagnosis and treatment of dyslipidaemia? ??Type 2 Diabetes?? (Metabolic Syndrome) Jiang et al. Non-HDL cholesterol and apolipoprotein B predict cardiovascular disease events among men with type 2 diabetes. Diabetes Care. 2004 Aug;27(8):1991-7.

51. Non-high-density lipoprotein cholesterol: why lower is better? Recent comparative trials of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) suggest that lower is better and that reducing low-density lipoprotein cholesterol (LDL-C) levels to below 100 mg/dL can provide additional clinical benefit. Non-high-density lipoprotein cholesterol (non-HDL-C) contains more atherogenic cholesterol than LDL-C and is considered a more accurate measurement of the total amount of atherogenic particles in the circulation. Therefore, the principle that "lower is better" may also apply to lowering levels of non-HDL-C. In persons with high triglycerides (200-499 mg/dL), LDL-C remains the primary target of therapy, but non-HDL-C is an important secondary therapeutic target. Non-HDL-C is strongly correlated with small dense LDL as well as apolipoprotein B, an established predictor of cardiovascular disease risk. Current evidence indicates that statins not only rapidly and dramatically reduce LDL-C, but also have a similar effect on non-HDL-C, and that the greater the reduction in LDL-C, the greater will be the reduction in non-HDL-C. Garg R; Vasamreddy CR; Blumenthal RS. Prev Cardiol 2005 8(3):173-7.

52. Arguments (in favour)  Both non-HDL cholesterol and apo B are markers for all of the potentially atherogenic lipoproteins ie, LDL, IDL, Lp(a) and atherogenic VLDL (including remnant-like particles)  Among these, LDL, IDL and Lp(a) are widely accepted as being atherogenic  Evidence is growing that most of the apo B- containing lipoproteins in VLDL contribute to atherosclerosis  Use of non-HDL cholesterol adds an element of simplicity to guidelines by combining all atherogenic lipoproteins into a single “fraction”

54. JAMA, July 20, 2005 Vol 294, No. 3 (Reprinted) ©2005 American Medical Association. All rights reserved. Non–HDL Cholesterol, Apolipoproteins A-I and B100, Standard Lipid Measures, Lipid Ratios, and CRP as Risk Factors for Cardiovascular Disease in Women

55. Arguments (Not in favour)  Earlier ATP reports, making use of both epidemiological data and clinical trial results, designated LDL cholesterol as the primary target  This designation has been widely accepted by medical community  Such that LDL is recognized by most physicians as first target of treatment  Modification(s) without stronger evidence would introduce considerable “confusion” into the general practice i.e., the pharmaceutical company “Market” interventions

56. Take Home Message The LDL-C test is still valuable, But the Apo B test adds valuable information.

57. One should also bear in mind that…  The use of apo B or non-HDL cholesterol will not completely eliminate the need for a fasting triglyceride level  When an elevated apo B-containing lipoproteins or non-HDL cholesterol warrants drug treatment, the clinician must determine whether to use as first-line therapy an agent that targets LDL cholesterol (e.g., Statins) or one that targets VLDL cholesterol (e.g., Fibrates)  In such cases, a measure of fasting triglycerides and calculation (or a direct measurement) of LDL cholesterol will still be needed

58. Allan D. Sniderman. Applying apoB to the diagnosis and therapy of the atherogenic dyslipoproteinemias: a clinical diagnostic algorithm. Curr Opin Lipidol 15:433–438; 2004.

59. I’m good Progression Regression ? ? ? ? ? ? HDL LDL VLDL IDL RLP Lp(a) If treatable, we’re not that bad!

60. To (measure apo) B Or NOT To (measure apo) B? Thank you for your attention