What does your ApoB value tell you about your risk of cardiovascular disease?

ApoB is a protein found on every atherogenic (atherosclerosis-promoting) lipoprotein particle in the blood, such as LDL, VLDL and IDL. Each of those particles carries exactly one ApoB molecule. Your ApoB value is therefore effectively a direct count of the number of harmful particles circulating through your blood vessels. In a systematic review of 15 studies involving 593,354 participants, ApoB outperformed LDL cholesterol as a predictor of cardiovascular disease (ASCVD) in all nine head-to-head comparisons.

The difference from LDL cholesterol becomes tangible in the UK Biobank, a study of 293,876 participants followed for eleven years. Among people with a high ApoB value, an ASCVD event occurred in 7.3 percent over ten years; among people with a low ApoB value, this was 4.0 percent, even when their LDL cholesterol was the same. This shows that two people with the same LDL value can still differ substantially in risk, depending on how many atherogenic particles they actually have. ApoB remained a significant predictor of new cardiovascular events after statistically accounting for LDL cholesterol, non-HDL cholesterol and triglycerides. Once ApoB was included in the model, LDL cholesterol, non-HDL cholesterol and triglycerides lost their own predictive power.

What matters is the total number of ApoB particles, not their type or size. In a prospective study of 207,368 UK Biobank participants, one standard deviation more ApoB particles was associated with a 33 percent higher risk of coronary heart disease (HR 1.33, 95% confidence interval 1.30-1.36). Breaking those particles down by subclass or size added no additional predictive value. What counts is the total number.

There is also a concept called 'excess ApoB': the portion of your ApoB value that is not explained by your LDL cholesterol alone. That surplus mainly reflects triglyceride-rich particles such as VLDL remnants. In a study of 95,108 people not using statins, followed over an average of 9.6 years, women with the highest excess ApoB had a 75 percent higher risk of ASCVD (HR 1.75, 95% CI 1.08-2.83) compared with the lowest group; in men this was 52 percent higher (HR 1.52, 95% CI 1.13-2.05). This association was dose-dependent and present regardless of LDL level.

ApoB does not, however, tell the complete story. First, elevated remnant cholesterol, a measure of triglyceride-rich lipoproteins, also predicts ASCVD on top of ApoB. In a pooled analysis of 17,532 individuals, log remnant cholesterol was associated with a hazard ratio of 1.65 (95% CI 1.45-1.89), even after adjustment for both LDL cholesterol and ApoB. Second, lipoprotein(a), abbreviated Lp(a), increases the risk of coronary heart disease independently of total ApoB particle count (HR per standard deviation 1.18, 95% CI 1.16-1.20). Adding Lp(a) to a risk model that already included ApoB measurably improved predictive accuracy. For a complete picture of your lipid risk, it is worthwhile to have Lp(a) measured alongside ApoB.

Despite the strong scientific basis, ApoB has not yet been widely adopted in everyday clinical practice. One practical barrier is the absence of clear, consistent treatment targets for ApoB in guidelines, whereas concrete target values for LDL cholesterol have existed for decades. The European societies for cardiology and atherosclerosis (ESC/EAS) acknowledged the added value of ApoB as early as 2019, but this has not yet led to universal implementation. If your doctor does not routinely measure your ApoB, it is reasonable to initiate that conversation, especially if you have an intermediate or elevated cardiovascular risk.