Background: The apolipoprotein B (apoB)/apoA-I ratio represents the balance of proatherogenic and antiatherogenic lipoproteins. The purpose of this study was to determine whether the apoB/apoA-I ratio was superior to any of the cholesterol ratios - total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C), low-density lipoprotein cholesterol (LDL-C)/HDL-C and non-HDL-C/HDL-C - in predicting the risk of coronary disease. Moreover, we examined whether any lipids, lipoproteins or cholesterol ratios add significant predictive information beyond that provided by the apoB/apoA-I ratio.
Methods: Plasma lipids, lipoproteins, apoB, and apoA-I were measured in 69,030 men and 57,168 women above 40 years of age. After a mean follow-up of 98 months, 1183 men and 560 women had died from a myocardial infarction in this prospective apolipoprotein-related mortality risk (AMORIS) study.
Results: High apoB and a high apoB/apoA-I ratio were strongly related to increased coronary risk, while high apoA-I was inversely related to risk. The apoB/apoA-I ratio was superior to any of the cholesterol ratios in predicting risk. This advantage was most pronounced in subjects with LDL-C levels <3.6 mmol/l. Addition of lipids, lipoproteins or any cholesterol ratio to apoB/apoA-I in risk models did not further improve the strong predictive value of apoB/apoA-I.
Conclusions: These results indicate that the apoB/apoA-I ratio is at present the best single lipoprotein-related variable to quantitate coronary risk. Given the additional advantages apolipoproteins possess - fasting samples are not required, apoB/apoA-I is a better index of the adequacy of statin therapy than LDL-C, and the measurement of apoB and apoA-I are standardized, whereas LDL-C and HDL-C are not - there would appear to be considerable advantage to integrating apolipoproteins into clinical practice.