Selection, validation, standardization, and performance of a designated comparison method for HDL-cholesterol for use in the cholesterol reference method laboratory network.

BACKGROUND: Accurate and precise HDL-cholesterol (HDL-C) measurements are essential for effective application of National Cholesterol Education Program treatment guidelines. The Cholesterol Reference Method Laboratory Network (CRMLN) assists manufacturers of in vitro diagnostic products to establish traceability to the accuracy base. CRMLN sought to implement a designated comparison method (DCM) that overcomes the impracticalities of the expensive and labor-intensive reference method for HDL-C.
METHODS: CRMLN evaluated candidate DCMs and selected one that uses 50-kDa dextran sulfate with magnesium ions as the precipitation reagent followed by measurement of cholesterol by the CDC reference method. After validating the method, we transferred it to all CRMLN laboratories and successfully standardized it using CDC frozen serum reference materials. CRMLN laboratories participate in monthly performance evaluations.
RESULTS: CRMLN laboratories were able to meet a precision goal, as indicated by SD, of </=0.03 mmol/L (1 mg/dL) 94.4% of the time. They were able to meet a bias goal of </=0.05 mmol/L (2 mg/dL) for HDL-C <1.09 mmol/L (42 mg/dL) 97.3% of the time and a goal of </=3% for HDL-C >/=1.09 mmol/L (42 mg/dL) 95.6% of the time. CRMLN is working to further improve its performance by implementing a bias criterion of 0.03 mmol/L (1 mg/dL) for all HDL-C concentrations.
CONCLUSIONS: CRMLN selected, validated, standardized, and implemented a DCM for HDL-C that is accurate, robust, transferable, and practical. The DCM is being used to assist manufacturers in calibrating their products so that ultimately, clinical laboratories using the products will more accurately measure HDL-C.