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.
OBJECTIVE
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 low-er 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.
Nakamura
Masakazu
M
Osaka Medical Center for Health Science and Promotion, CRMLN Lipid Reference Laboratory, Higashinari-ku, Osaka, Japan. xnakamura@kenkoukagaku.jp
Koyama
Isao
I
Iso
Hiroyasu
H
Sato
Shinichi
S
Okazaki
Mitsuyo
M
Kayamori
Yuzo
Y
Kiyama
Masahiko
M
Kitamura
Akihiko
A
Shimamoto
Takashi
T
Ishikawa
Yoshinori
Y
D050197:Atherosclerosis / Q000209:etiology*; D015982:Bias; D002318:Cardiovascular Diseases / Q000209:etiology; D002487:Centers for Disease Control and Prevention, U.S.; D002784:Cholesterol / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood* / Q000592:standards; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan; D024821:Metabolic Syndrome / Q000150:complications; D011237:Predictive Value of Tests; D012015:Reference Standards; D015203:Reproducibility of Results; D014481:United States
D008078:Cholesterol, LDL; D002784:Cholesterol