Validation of the Martin/Hopkins and Sampson/NIH Equations in Comparison with a Direct Homogeneous Assay in Patients with Hypertriglyceridemia

Background: Recently, novel methods have been developed for the estimation of low-density lipoprotein-cholesterol (LDL-C) in patients with hypertriglyceridemia. Herein, the equations were validated by comparing them to a direct homogeneous assay provided by Roche Diagnostics (Cobas 8000).Methods: LDL-C levels were directly measured using the Roche Cobas assay (DLDL) and estimated using the Friedewald (FLDL), Martin/Hopkins (MLDL), extended Martin/Hopkins (EMLDL), and Sampson (SLDL) equations for 52,589 patients with triglyceride (TG) levels <800 mg/dL.The performance of the four equations was compared using Bland-Altman plots and the mean absolute difference (MAD).The Cochran's Q test was used to compare the performance of various equations between the DLDL and TG groups.Results: The MLDL and EMLDL results were more accurate than the results of other LDL-C equations for TG levels ranging from 400 to 799 mg/ dL (MLDL: MAD=12.63;EMLDL: MAD=13.05;FLDL: MAD=41.46; and SLDL: MAD=20.61;P < 0.001).For TG levels 150 mg/dL, the MLDL and EMLDL results showed superior concordance with the DLDL result (MLDL, 69.9%; EMLDL, 69.8%; SLDL, 58.1%; and FLDL, 38.3%; P < 0.001), indicating that the Martin/Hopkins or extended Martin/Hopkins methods were the most optimal estimation methods for hypertriglyceridemia. Conclusions: The MLDL or EMLDL results were optimal for the accurate estimation of LDL-C levels in clinical laboratories using Roche analyzers for patients with hypertriglyceridemia (TG levels of 150-799 mg/dL).Using the FLDL or SLDL results frequently led to undertreatment due to their tendency for underestimation.