Characterization of lipoprotein profiles in patients with hypertriglyceridemic Fredrickson-Levy and Lees dyslipidemia phenotypes: the Very Large Database of Lipids Studies 6 and 7

INTRODUCTION: The association between triglycerides (TG) and cardiovascular diseases is complex. The classification of hypertriglyceridemic (HTG) phenotypes proposed by Fredrickson, Levy and Lees (FLL) helps inform treatment strategies. We aimed to describe levels of several lipoprotein variables from individuals with HTG FLL phenotypes from the Very Large Database of Lipids. MATERIAL AND METHODS: We included fasting samples from 979,539 individuals from a contemporary large study population of US adults. Lipids were directly measured by density-gradient ultracentrifugation using the Vertical Auto Profile test while TG levels were measured in whole plasma using the Abbott ARCHITECT C-8000 system. Hyperchylomicronemic (Hyper-CM) and non-chylomicronemic (non-CM) phenotypes were defined using computationally derived models. Individuals with FLL type IIa phenotype were excluded. Distributions of lipid variables were compared using medians and Kruskal-Wallis test. RESULTS: A total of 11.9% (n = 116,925) of individuals met criteria for HTG FLL phenotypes. Those with hyper-CM phenotypes (n = 5, < 0.1% of population) had two-fold higher TG levels compared with non-chylomicronemic (non-CM) individuals (11.9% of population) (p < 0.001). Type IIb individuals had the highest non-HDL-C levels (median 242 mg/dl). Cholesterol in large VLDL(1+2) particles was higher than in small VLDL(3) particles in all phenotypes except FLL type III. Hyper-CM phenotypes had significantly lower HDL-C levels but greater HDL(2)/HDL(3)-C ratio compared to non-CM phenotypes. Cholesterol content of the lipoprotein (a) peak was significantly higher in the hyper-CM groups compared to non-CM phenotypes (p < 0.0001). CONCLUSIONS: This observational hypothesis-generating study provides insight into the complexity of lipid metabolism in HTG phenotypes, including less traditional lipid measures such as LDL density, HDL subclasses and Lp(a)-C.