Apolipoprotein B

Apolipoprotein B (apoB) is contained is contained in LDL cholesterol and all other atherogenic lipoproteins. Because it is present in all atherogenic particles, apoB is a better predictor of of cardiovascular risk than LDL cholesterol (LDL-C). 

ApoB and LDL-C concentrations tend to parallel each other, but can diverge following statin therapy. When LDL-C decreases to the treatment threshold, but apoB remains elevated, apoB is the better predictor of future cardiovascular outcomes.

 According to the Expert Clinical Consensus from the National Lipid Association, measurement of apoB may be helpful in the following situations:

• Patients with borderline atherosclerotic cardiovascular disease risk who prefer not to start statin therapy. If apoB suggests low risk, then statin therapy could be withheld.
• Patients with obesity and insulin resistance have smaller cholesterol-depleted LDL particles that result in lower LDL-C levels. Elevated apoB levels may drive the decision to treat with a statin.  
• Patients on statin therapy who are under consideration for therapeutic intensification. If the LDL-C is at goal and apoB is above threshold, treatment intensification may be considered

According to the consensus statement, the treatment thresholds for LDL-C and apoB are:

In summary, measurement of apoB can be helpful for further risk stratification in patients with borderline or intermediate LDL-C levels, and for deciding whether further intensification of lipid-lowering therapy may be warranted when the LDL threshold has been reached. 

The consensus statement does not state that apoB should be measured in all patients or that it is the standard of care. The use of apoB to assess the effectiveness of lipid lowering therapies remains a matter of clinical judgement. 

Reference

Soffer et al, Role of apolipoprotein B in the clinical management of cardiovascular risk in adults: An expert clinical consensus from the national lipid association, Journal of Clinical Lipidology, https://doi.org/10.1016/j.jacl.2024.08.013