Analytical and clinical performance of two homogeneous assays for measuring of LDL-cholesterol

Abstract

A clinical laboratory currently estimates LDL-Cholesterol (LDL-C) concentration using the Friedewald calculation, which requires fasting specimens and is subject to error with increasing triglycerides levels. We evaluated the analytical and clinical performance of the direct LDL-C assay from two companies, Roche Diagnostics (LDL-CRoche) and Wako Pure Chemical (LDL-CWako). Both methods meet current guidelines for precision with within-run coefficients of variation less than 3 per cent. The LDL-CRoche assay correlated well with the LDL-C from the Friedewald equation (LDL-CFried' r = 0.958, y = 0.85x + 17.08 mg/dL, n = 422). The LDL-CWako assay also correlated with the LDL-CFried (r = 0.946, y = 0.86x + 7.81 mg/dL, n = 422). In addition, at the medical decision cutoff points, LDL-CRoche assay and LDL-CWako showed positive predictive values of 87.44 per cent and 69.67 per cent respectively. We conclude that the LDL-CRoche assay meets the currently established analytical and clinical performance, but LDL-CWako assay meets only analytical performance. Clinical performance needs further evaluation.