There is abundant evidence that the risk of atherosclerotic
vascular disease is directly related to plasma
cholesterol levels. Accordingly, all of the national and transnational screening and therapeutic guidelines are based on total or
LDL cholesterol. This presumes that
cholesterol is the most important
lipoprotein-related proatherogenic risk variable. On the contrary, risk appears to be more directly related to the number of circulating atherogenic particles that contact and enter the arterial wall than to the measured concentration of
cholesterol in these
lipoprotein fractions. Each of the atherogenic
lipoprotein particles contains a single molecule of
apolipoprotein (
apo) B and therefore the concentration of
apo B provides a direct measure of the number of circulating atherogenic
lipoproteins. Evidence from fundamental, epidemiological and clinical trial studies indicates that
apo B is superior to any of the
cholesterol indices to recognize those at increased risk of
vascular disease and to judge the adequacy of
lipid-lowering
therapy. On the basis of this evidence, we believe that
apo B should be included in all guidelines as an
indicator of cardiovascular risk. In addition, the present target adopted by the Canadian guideline groups of an
apo B <90 mg dL(-1) in high-risk patients should be reassessed in the light of the new clinical trial results and a new ultra-low target of <80 mg dL(-1) be considered. The evidence also indicates that the
apo B/
apo A-I ratio is superior to any of the conventional
cholesterol ratios in patients without symptomatic
vascular disease or diabetes to evaluate the
lipoprotein-related risk of
vascular disease.