Traditional and Emerging Lipid Markers for Cardiovascular Risk Assessment in Young vs Older Adults

The utility of emerging lipid markers-apolipoprotein B (apoB) and lipoprotein(a) (Lp[a])-for improving atherosclerotic cardiovascular disease (ASCVD) risk assessment beyond traditional lipid measures remains uncertain, particularly in young adults.

To evaluate associations of traditional and emerging lipid markers with ASCVD and assess the incremental value of emerging markers beyond established risk models.

This prospective cohort study included adults aged 18 years or older without cardiovascular disease from 3 US cohort studies (Coronary Artery Risk Development in Young Adults, the Framingham Heart Study Offspring, and the Multi-Ethnic Study of Atherosclerosis [MESA]). Data were analyzed from April to June 2025.

Lipid markers, including low-density lipoprotein (LDL) cholesterol, non-high-density lipoprotein (HDL) cholesterol, remnant cholesterol, total-to-HDL cholesterol ratio, apoB, and Lp(a).

Hazard ratios (HRs) for incident ASCVD per-SD increase in lipid marker levels, estimated using Cox proportional hazards regression models adjusted for demographic and clinical factors, and model performance metrics (Harrell concordance index [C-index], net reclassification improvement [NRI], and mean calibration) comparing models including the risk estimated by the Predicting Risk of Cardiovascular Disease Events (PREVENT) base equations against models that additionally included each lipid marker.

Among 10 519 participants (mean [SD] age, 48.3 [15.7] years; 53.0% female), 1103 ASCVD events occurred during a median follow-up of 21.3 (IQR, 16.5-26.0) years. ApoB was positively associated with ASCVD events, especially in younger adults aged 18 to 39 years (adjusted HR [AHR] per-SD increase, 1.53; 95% CI, 1.30-1.79) vs those aged 40 years or older (AHR, 1.13; 95% CI, 1.06-1.20) (P < .001 for interaction). Lp(a) as a continuous variable was associated with a marginal increase in ASCVD in adults aged 40 years or older (AHR, 1.07; 95% CI, 1.00-1.16) but not in younger adults (AHR, 1.02; 95% CI, 0.87-1.19) (P = .61 for interaction). When dichotomized (>50 vs ≤50 mg/dL), Lp(a) was associated with ASCVD in adults aged 40 years or older (AHR range, 1.36; 95% CI, 1.13-1.64) but not in younger adults (AHR, 0.98; 95% CI, 0.66-1.45) (P = .42 for interaction). Adding apoB to 10-year ASCVD risk estimated by the PREVENT base equations was associated with improved risk reclassification in younger adults (continuous NRI, 0.67; 95% CI, 0.23-1.09) but not in those aged 40 years or older (continuous NRI, 0.16; 95% CI, -0.05 to 0.27). ApoB was also associated with improved 30-year risk reclassification in younger adults (continuous NRI, 0.47; 95% CI, 0.02-0.84). Dichotomized Lp(a), but not continuous Lp(a), was associated with improved 10-year NRI only in MESA (0.13; 95% CI, 0.03-0.24).

In this cohort study of 10 519 adults, adding apoB to PREVENT-estimated ASCVD risks was associated with improved risk reclassification, particularly in younger adults. However, the clinical importance of these modest improvements remains uncertain.