Ten-year evaluation of homogeneous low-density lipoprotein cholesterol methods developed by japanese manufacturers,application of the centers for disease control and prevention/cholesterol reference method laboratory network lipid standardization protocol

Aim: the risk index for atherosclerotic cardiovascular diseases in the japanese metabolic syndrome-focused health checkup program was changed from total cholesterol (tc) to low-density lipoprotein cholesterol (ldl-c). we discuss the validity of this change with respect to standardization. methods: the beta-quantification procedure of the centers for disease control and prevention (cdc) uses the ldl-c reference value as a target. clinical laboratories and commercial manufacturers use homogeneous ldl-c methods for standardization. (a) for clinical laboratories,ldl-c in 648 samples requested from 108 hospitals was analyzed. (b) manufacturers participated in the cdc/ cholesterol reference method laboratory network ldl-c standardization protocol. the standardization was conducted with a performance follow-up for the 10-year period from 1998 to 2008 at 2-year intervals,6 times. results: (a) in clinical laboratories,acceptable ldl-c levels within ± 4% of the cdc s criteria remained 70.4%,456 of 648 subjects. negative maximum bias deviating from the ldl-c target value was - 35.8%,- 52.5 mg/dl,and positive maximum bias was + 24.5%,+ 32.3 mg/dl. (b) for manufacturers,the standardization achievement rate of the analytical reagent/instrument/calibrator system in the last four standardizations from 2002 to 2008 remained on average 66.6%,far lower than the level required. conclusions: the standardization achievement rate of homogeneous ldl-c methods was much lower than that of tc. tc should still be used as a risk index for atherosclerotic cardiovascular diseases. the standardization achievement rate of homogeneous ldl-c should be maintained at 100%,at least using samples with normal lipoprotein profiles. the accuracy and specificity of ldl-c should be further improved before practical and clinical use.