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The Apo B:Apo A-I Ratio: A Role in CV Risk Assessment?

This ratio performed no better than the total cholesterol:HDL cholesterol ratio in determining CAD risk.

Unlike LDL levels, apolipoprotein (apo B) levels reflect all types of pro-atherogenic particles. Furthermore, apolipoprotein A-I (apo A-I) is more important than HDL-cholesterol content for biochemical pathways that render HDL antiatherogenic. Might the apo B:apo A-I ratio predict cardiac risk better than do traditional lipid measurements or the Framingham risk score? To find out, investigators performed a nested case-control study among participants in the European Prospective Investigation into Cancer and Nutrition–Norfolk.

Apolipoprotein and lipid levels were measured for 869 cases (individuals who developed fatal or nonfatal coronary artery disease) and 1511 matched controls (individuals who remained CAD-free) over a mean follow-up of 6 years. Upon enrollment, participants were 45–79 years old and apparently healthy. Occurrence of CAD during follow-up was determined using a regional health authority database (hospitalizations) and U.K. Office of National Statistics records (deaths).

The apo B:apo A-I ratio was associated with future CAD events independent of traditional lipid values, including total cholesterol:HDL cholesterol ratio (adjusted odds ratio, 1.85), and independent of the Framingham risk score (OR, 1.77). However, the apo B:apo A-I ratio did no better than lipid values in discriminating between individuals who would and would not develop CAD, and it added little to the predictive value of the Framingham risk score. In addition, this ratio incorrectly classified 41% of cases and 50% of controls.

Comment: Measuring apo B and apo A-I, the main structural proteins of atherogenic and antiatherogenic lipoproteins and particles, adds little to existing measures of CAD risk assessment and discrimination in the general population. Nonetheless, it may be useful in some settings because fasting samples are not needed.

— Joel M. Gore, MD

Published in Journal Watch Cardiology May 9, 2007

Citation(s):

van der Steeg WA et al. Role of the apolipoprotein B–apolipoprotein A-I ratio in cardiovascular risk assessment: A case–control analysis in EPIC-Norfolk. Ann Intern Med 2007 May 1; 146:640-8.

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