Low-density lipoprotein cholesterol versus particle number in middle school children

Abstract

Objectives: To characterize lipids and lipoproteins in a diverse school-based cohort and identify features associated with discordance between low-density lipoprotein cholesterol (LDL-C) and LDL particle (LDL-P).

Study design: Sixth-grade children enrolled in the HEALTHY trial (n = 2384; mean age 11.3 ± 0.6 years; 54.2% female) were evaluated for standard lipids, lipoprotein particles measured by nuclear magnetic resonance, and homeostatic model of insulin resistance. Characteristics of subgroups with values of LDL-C and LDL-P discordant by >20 percentile units, an amount reasoned to be clinically significant, were compared.

Results: Four-hundred twenty-eight (18%) of children were in the LDL-P < LDL-C subgroup and 375 (16%) in the LDL-P > LDL-C subgroup. Those with LDL-P > LDL-C had significantly greater body mass index, waist circumference, homeostatic model of insulin resistance, triglycerides, systolic and diastolic blood pressure, and reflected a greater Hispanic ethnic composition but fewer of black race than both the concordant (LDL-P ≅ LDL-C) and opposite discordant (LDL-P < LDL-C) subgroups.

Conclusions: There is as much lipoprotein cholesterol compositional heterogeneity in sixth graders as has been described in adults and a discordant atherogenic phenotype of LDL-P > LDL-C, common in obesity, is often missed when only LDL-C is considered. Conversely, many children with moderate-risk cholesterol measures (75th to 99th percentile) have a lower LDL-P burden.

Trial registration: ClinicalTrials.gov NCT00458029.

Keywords: Apolipoprotein B; BMI; Body mass index; CVD; Cardiovascular disease; HDL-C; HDL-P; HOMA-IR; High-density lipoprotein cholesterol; High-density lipoprotein particle; Homeostatic model of insulin resistance; LDL; LDL-C; LDL-P; Low-density lipoprotein; Low-density lipoprotein cholesterol; Low-density lipoprotein particle; NMR; Nuclear magnetic resonance; TC; TG; Total cholesterol; Triglycerides; VLDL; VLDL-P; Very-low-density lipoprotein; Very-low-density lipoprotein particle; apoB.

Figure 1

Amount of agreement/disagreement between LDL-P and LDL-C as differences in the sample percentiles for each and the percent of the sample that falls into each range of differences. There is relative agreement or concordance for two-thirds of the study group in whom LDL-C and LDL-P percentiles fall within 20 percentile points. The two measures disagree or are discordant for the rest of the study group, varying from 20 to 80 percentile points.