Estimation of VLDL, IDL, LDL, HDL2, apoA-I, and apoB from the Friedewald inputs-apoB and IDL, but not LDL, are associated with mortality in type 1 diabetes

Background. There is an unmet need for a straightforward and cost-effective assessment of multiple lipoprotein risk factors for vascular diseases. Aims. 1) To study the relation of various lipoprotein lipid and apolipoprotein (apo) measures on the Friedewald inputs, i.e. plasma triglycerides (TG), cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C). 2) To build up regression models for the appropriate measures based solely on the Friedewald inputs. Methods. Data were available for 1,775 plasma samples, from which very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and HDL were also isolated by ultracentrifugation. For HDL2-C and apolipoproteins, 343 and 247 samples were available, respectively. Results. Accurate models were obtained for VLDL-TG (cross-validation r = 0.98), LDL-C (r = 0.91), HDL2-C (r = 0.92), apoA-I (r = 0.92), and apoB (r = 0.95). A semi-quantitative model was obtained for IDL-C (r = 0.78). Due to the anticipated role of IDL-C in atherosclerosis, it was still kept within the accepted models and pursued further. The associations of the estimates with premature deaths were studied in 4,084 patients with type 1 diabetes. The associations of IDL-C and LDL- C were markedly different, the best predictors of mortality being apoB, apoB to apoA-I ratio, and IDL-C. Conclusions. The new models allow identification of clinically relevant lipoprotein profiles with no added cost to the conventional Friedewald formula.