Abstract Body (Do not enter title and authors here): Background
ApoB-containing lipoproteins, including LDL, are well-established causes of atherosclerotic cardiovascular disease (ASCVD). While typically highly correlated, apoB and LDL-C levels can diverge due to differences in lipid composition and response to lipid-lowering therapies (LLT). Furthermore, the definition of cutpoints can influence clinically-relevant discordance between LDL-C and apoB, which may inform guideline-directed treatment. Recent proposals suggest aligning LDL-C and apoB goals using equivalent cutpoints (<55, <70, and <100 mg/dL). Clarifying the prevalence and impact of discordance has important implications for clinical care.

Objectives
To quantify the prevalence of LDL-C and apoB discordance among US adults when applying equivalent LDL-C and apoB goals.

Methods
We included 298,578 adults (age ≥18) with available apoB and LDL-C measurements from the Very Large Database of Lipids (VLDbL), a population-representative convenience sample with clinical lipid measurements obtained in 2015-2019. We also included 2,707 statin-treated adults from the National Health and Nutrition Examination Survey (NHANES) from 2005-2016 to assess the effects of statin use on discordance. The Martin-Hopkins equation was used to calculate LDL-C. Equivalent goals of <55, <70, and <100 mg/dL for LDL-C and apoB were applied.

Results
In VLDbL (mean age 56 years, 57% female), 43.2% had apoB and LDL-C discordance (Table 1). In NHANES statin-treated individuals (mean age 66 years, 47% female), 33.9% had apoB and LDL-C discordance. Among those reaching LDL-C goals of <55, <70, and <100 mg/dL, apoB was discordantly elevated in up to 33%, 12%, and 2%, respectively, for equivalent goals (Figure 1). In contrast, among those reaching apoB goals of <55, <70, and <100 mg/dL, LDL-C was discordantly elevated in up to 61%, 56%, and 49%, respectively, for equivalent goals (Figure 2).

Conclusions
LDL-C and apoB discordance was prevalent among US adults, most often due to discordant LDL-C elevation in those reaching equivalent apoB goals, with less discordance in statin-treated adults. These results suggest that using LDL-C and apoB individually as treatment goals could lead to substantially different patient populations eligible for LLT to reduce ASCVD risk, while utilizing both as complementary goals could maximize eligibility for LLT. Taken together, these findings suggest an opportunity for an individualized approach to ASCVD risk optimization.