Thursday, April 28, 2005

Improving Assessment of Cardiovascular Disease Risk Factors by Standardizing Manufacturers of Diagnostic Assays

Mahnaz Dasti, Mary M. Kimberly, and Gary L. Myers.

To correctly diagnosis and manage coronary artery disease, physicians need accurate, reliable lipid and lipoprotein measurements. The National Cholesterol Education Program (NCEP) recommended that these measurements be traceable to the Centers for Disease Control and Prevention (CDC) reference methods. More than 100,000 clinical laboratories are in the United States, which makes direct standardization by CDC impractical.

CDC established the Cholesterol Reference Method Laboratory Network (CRMLN) to provide traceability to reference methods. The CRMLN improves laboratory performance by working with manufacturers to evaluate the performance of clinical diagnostic products. This poster reports the certification activity of manufacturers.

To ensure accurate calibration, manufacturers must demonstrate acceptable performance of their assays on the measurement of human serum samples. To accomplish this, manufacturers perform a sample comparison with a CRMLN laboratory. Those that meet NCEP performance criteria for imprecision and inaccuracy receive a Certificate of Traceability. The data reported for manufacturers were gathered from November 2002 to November 2004.

Manufacturers evaluated 69 methods for total cholesterol (TC); 86% of these were certified. Seventy-two high-density lipoprotein cholesterol (HDL-C) methods were evaluated; 67% were certified. Thirty-four low-density lipoprotein cholesterol (LDL-C) methods were evaluated; 82% were certified. Manufacturers that were certified had an average percent bias ranging from -2.9 to 2.1% for TC; from -4.4 to 5.4% for HDLC; and from -3.5 to 2.8% for LDLC. Manufacturers that were certified had an average percent coefficient of variation (CV) ranging from 0.3 to 2.5% for TC; from 0.4 to 4.0% for HDLC; and from 0.7 to 3.3% for LDLC.

By providing traceability for manufacturers, the CRMLN improves the reliability of cholesterol testing in clinical laboratories. This leads to improved patient care because the methods used by clinical laboratories are properly calibrated.

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