A reference method laboratory network for cholesterol: A model for standardization and improvement of clinical laboratory measurements

Background: Accurate and precise measurement of blood cholesterol plays a c entral role in the National Cholesterol Education Program's strategy to red uce the morbidity and mortality attributable to coronary heart disease. Mat rix effects hamper the ability of manufacturers to adequately calibrate and validate traceability to the National Reference System for Cholesterol (NR S/ CHOL). CDC created the Cholesterol Reference Method Laboratory Network ( CRMLN) to improve cholesterol measurement by assisting manufacturers of in vitro diagnostic products with validation of the traceability of their assa ys to the NRS/CHOL, Methods: CRMLN laboratories established the CDC cholesterol reference metho d (modification of the Abell-Levy-Brodie-Kendall chemical method) and are s tandardized using CDC frozen serum reference materials. CRMLN laboratories use common quality-control materials and participate in monthly external pe rformance evaluations conducted by CDC. The CRMLN performance criteria requ ire member laboratories to agree with CDC within +/- 1.0% and maintain a CV less than or equal to2.0%. Results: From 1995 to 2000, the CRMLN laboratories met the accuracy criteri on 97% of the time and the precision criterion 99% of the time. During this time period, the CRMLN maintained an average bias to CDC of 0.01% and an a verage collective CV of 0.33%, Conclusions: CDC established the CRMLN as the first international reference method laboratory network. The CRMLN assists manufacturers in the validati on of the calibration of their diagnostic products so that clinical laborat ories can measure blood cholesterol more reliably. The CRMLN can serve as a model for other clinical analytes where traceability to a hierarchy of met hods is needed and matrix effects of the field methods with processed calib rators or reference materials are present. (C) 2000 American Association fo r Clinical Chemistry.