Evidence for this analysis is not strong. There are no randomized studies that demonstrate that this test is beneficial in assigning therapy. Epidemiologic literature has demonstrated an inverse relationship between levels of high-density lipoprotein (HDL) and cardiovascular risk, indicating that HDL may have a protective role against cardiovascular disease. HDL particles exhibit considerable heterogeneity, and it has been proposed that various subclasses of HDL may have a greater role in protection from atherosclerosis. HDL contains 2 associated apolipoproteins, i.e., AI and A2. HDL particles can also be classified on whether they contain apolipoprotein A-1 only or whether they contain both apolipoprotein A-1 and A-2. An alternative to measuring the concentration of subclasses of HDL, such as HDL2 and HDL3, is direct measurement of HDL particle size and/or number. Several commercial labs offer these measurements of HDL particle size and number. Recently, measurement of apo A-I has used measurement of HDL particle number as a surrogate, based on the premise that each HDL particle contains one apo A-I molecule. Direct measurement of apo A-I has been proposed as more accurate than the traditional use of HDL level in evaluation of the cardioprotective, or “good,” cholesterol. In addition, the ratio of apo B/apo A-I has been proposed as a superior measure of the ratio of proatherogenic (i.e., “bad”) cholesterol to anti-atherogenic (i.e., “good”) cholesterol.
Traditional lipid risk factors such as total HDL and low-density-lipoprotein cholesterol (LDL-C), while predictive on a population basis, are weaker markers of risk on an individual basis. Only a minority of subjects with elevated LDL and cholesterol levels will develop clinical disease, and up to 50% of cases of coronary artery disease (CAD) occur in subjects with “normal” levels of total and LDL cholesterol. Thus, there is considerable potential to improve the accuracy of current cardiovascular risk prediction models and they are n0t a universallya ccepted test. There is good epidemiological evidence but no prospective studies.Framingham and other studies showed how diet adn exrcize can change HDL levels, which are presumed, but not proven to improve health. The same can be said of drug induced changes in HDL and LDL, where there is evidence that supports it prospectively. However, for the fractionated HDL test, no such evidence currenlty exists.
Chapman M, Assmann G, Fruchart J, Shepherd J, Sirtori C. Raising high-density lipoprotein cholesterol with reduction of cardiovascular risk: the role of nicotinic acid – a position paper developed by the European Consensus Panel on HDL-C. Cur Med Res Opin. 2004 Aug;20(8):1253-68.
Reducing risk by raising HDL-cholesterol: the evidence. # European Heart Journal Supplements Vol 8 Suppl F p. F23-F29