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

A clinical laboratory currently estimates LDL-Cholesterol (LDL-C) concentration using the Friedewald calculation, which requires fasting specimens and is subject to error with in- creasing triglycerides levels. We evaluated the analytical and clinical performance of the direct LDL-C assay from two companies, Roche Diagnostics (LDL-CRoch) and Wako Pure Chemical (LDL-CwakJ 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-CFriect' r = 0.958, y = 0.85x + 17.08 mg/dL, n = 422). The LDL-Cwako assay also correlated with the LDL-CFriect (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. Key word : Homogeneous LDL-C Assays, Analytical and Clinical Performance