Reference Standardization and Analytical Performance of a Liquid Homogeneous High-Density Lipoprotein Cholesterol Method Compared With Chemical Precipitation Method

Abstract

Abstract Background.—The use of high-density lipoprotein cholesterol (HDL-C) levels as a risk factor for coronary heart disease necessitates an accurate and precise method for measuring HDL-C. The Centers for Disease Control and Prevention HDL-C reference method (RM) and designated comparison method (DCM) are time-consuming, expensive, and impractical for routine clinical use. We evaluated the Liquid N-geneous (LN-gen) HDL-C assay (Genzyme Diagnostics, Cambridge, Mass) to determine if this homogeneous reagent meets the National Cholesterol Education Program requirements for HDL-C evaluation. Design.—Accuracy of the LN-gen HDL-C assay was compared in combination with phosphotungstic acid (PTA) precipitation with DCM HDL-C for normotriglyceridemic serum specimens (triglycerides <2.0 g/L) and with RM HDL-C for specimens with triglycerides levels ≥2.0 g/L. Setting.—Genzyme Diagnostics (with RM and DCM assayed by Pacific BioMetrics Inc, Seattle, Wash) and the Lipid Reference Laboratory of the University Hospital Rotterdam, The Netherlands. Results.—Linear regression to DCM (n = 90) was (LN-gen = 1.015 DCM + 0.01 g/L, r = 0.993, SE = 0.015 g/L) and (PTA = 1.004 DCM − 0.017 g/L, r = 0.980, SE = 0.025 g/L), with a mean percent bias to DCM of 3.3% and −2.8% for LN-gen and PTA, respectively. The comparison with RM (n = 69) showed an increased mean bias for PTA (−5.8%) as compared with LN-gen (1.5%). The correlation and regression equations were (LN-gen = 1.020 RM − 0.002 g/L, r = 0.985, SE = 0.017 g/L) and (PTA = 1.042 RM − 0.032 g/L, r = 0.984, SE = 0.018 g/L). The precision of LN-gen was confirmed at <2.1% coefficient of variation, and the total error was calculated to be ≤7.7% for both normotriglyceride and elevated triglyceride specimens at HDL-C decision points of 0.35 g/L and 0.60 g/L. Conclusions.—The LN-gen HDL-C assay offers a cost-effective convenient method for meeting the 1998 precision, bias, and total error recommendations of the National Cholesterol Education Program.