115 Apolipoprotein B Reveals Systematic Underestimation of Atherogenic Lipoprotein Burden by LDL Cholesterol Across Estimation Methods

Introduction/Objective LDL-C remains the primary target for lipid-lowering therapy, yet reflects cholesterol mass rather than atherogenic particle number. Apolipoprotein B (apoB) directly reflects atherogenic particle concentration and may better capture cardiovascular risk, particularly in triglyceride-rich lipoprotein states. The aim of the study was to investigate the agreement between apoB and measured and calculated LDL-C. Methods/Case Report We analyzed 526 paired lipid measurements, including apoB, non-HDL cholesterol, directly measured LDL-C, and Friedewald, Martin, Sampson, and modified Sampson LDL-C. Directional discordance was defined as LDL-C < 1 00 mg/dL with apoB ≥90 mg/dL. Discordance rates, systematic bias, and concordance with apoB were evaluated overall and across triglyceride concentrations ( < 1 50, 150–299, and ≥300 mg/dL). Results LDL-C demonstrated substantial discordance with apoB, predominantly reflecting underestimation of atherogenic burden. Discordance increased across triglyceride strata, rising from 1.4% at triglycerides < 1 50 mg/dL to 4.8% at 150–299 mg/dL and 15.2% at ≥ 300 mg/dL. Friedewald showed the greatest bias, whereas Martin and modified Sampson modestly improved concordance. Non-HDL cholesterol closely tracked apoB across sex and triglyceride strata. Conclusion LDL-C underestimates atherogenic burden in hypertriglyceridemia. Differences among LDL-C estimation methods mitigate but do not resolve this limitation; apoB and non-HDL cholesterol may better reflect residual risk and atherogenic burden.