HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit an electronic Letter to the Editor about this paper Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (19) Citing Articles via Google Scholar Google Scholar Articles by Miller, W. G. Articles by Jayne, E. C. Search for Related Content PubMed PubMed Citation Articles by Miller, W. G. Articles by Jayne, E. C. Related Collections Lipids, Lipoproteins, and Cardiovascular Risk Factors

Performance of Four Homogeneous Direct Methods for LDL-Cholesterol

¹ Department of Pathology, Virginia Commonwealth University Health System, Richmond, VA 23298.

² CDC, National Center for Environmental Health, Division of Laboratory Sciences, Special Activities Branch, Atlanta, GA 30341.

^aAddress correspondence to this author at: Virginia Commonwealth University, 401 N. 13th St., Richmond, VA 23219. Fax 804-828-0353; e-mail millerg{at}hsc.vcu.edu.

Background: Homogeneous LDL-cholesterol methods from Genzyme, Reference Diagnostics, Roche, and Sigma were evaluated for precision, accuracy, and specificity for LDL in the presence of abnormal lipoproteins.

Methods: Each homogeneous method was performed by a Roche/Hitachi 911 according to the vendors’ instructions, and the results were compared with the ß-quantification reference method. We measured precision over 20 days using quality-control and frozen serum specimens. Sera from 100 study participants, including 60 with hyperlipidemias, were assayed by each method. Accuracy was evaluated from regression and total error analysis. Specificity was evaluated from the bias (as a percentage) vs concentration of triglycerides.

Results: The total CV was <2% for all methods. Regression slope and intercept (with 95% confidence intervals) were as follows: Genzyme, 0.955 (0.92 to 0.99) and 30.3 (-12 to 73) mg/L; Reference Diagnostics, 0.975 (0.93 to 1.02) and -8 (-63 to 47) mg/L; Roche, 1.067 (1.02 to 1.11) and -101 (-161 to -42) mg/L; and Sigma, 0.964 (0.91 to 1.02) and 164 (89 to 239) mg/L. The percentages of individual results with >12% bias were as follows: Genzyme, 8.0%; Reference Diagnostics, 11.0%; Roche, 10.0%; and Sigma, 30.0%. Total error calculated from mean systematic bias and all-sources random bias was as follows: Genzyme, 12.6%; Reference Diagnostics, 16.5%; Roche, 41.6%; and Sigma, 38.3%. Slopes of bias (as a percentage) vs triglycerides were P <0.001 for all methods except the Roche method, which was P = 0.094.

Conclusions: The evaluated methods show nonspecificity toward abnormal lipoproteins, thus compromising their ability to satisfy the National Cholesterol Education Program goal for a total error of <12%. These homogeneous LDL-cholesterol results do not improve on the performance of LDL-cholesterol calculated by the Friedewald equation at triglyceride concentrations <4000 mg/L.

The following articles in journals at HighWire Press have cited this article:

				S. de Ferranti, D. Shapiro, R. Markowitz, E. Neufeld, N. Rifai, and H. Bernstein Nonfasting Low-Density Lipoprotein Testing: Utility for Cholesterol Screening in Pediatric Primary Care Clinical Pediatrics, June 1, 2007; 46(5): 441 - 445. [Abstract] [PDF]

				D. J. Blom, F. H. O'Neill, and A. D. Marais Screening for Dysbetalipoproteinemia by Plasma Cholesterol and Apolipoprotein B Concentrations Clin. Chem., May 1, 2005; 51(5): 904 - 907. [Full Text] [PDF]

				E. T. Bairaktari, K. I. Seferiadis, and M. S. Elisaf Evaluation of Methods for the Measurement of Low-Density Lipoprotein Cholesterol Journal of Cardiovascular Pharmacology and Therapeutics, January 1, 2005; 10(1): 45 - 54. [Abstract] [PDF]

				J. S. Krouwer Critique of the Guide to the Expression of Uncertainty in Measurement Method of Estimating and Reporting Uncertainty in Diagnostic Assays Clin. Chem., November 1, 2003; 49(11): 1818 - 1821. [Abstract] [Full Text] [PDF]

				S. Usui, H. Kakuuchi, M. Okamoto, Y. Mizukami, and M. Okazaki Differential Reactivity of Two Homogeneous LDL-Cholesterol Methods to LDL and VLDL Subfractions, as Demonstrated by Ultracentrifugation and HPLC Clin. Chem., November 1, 2002; 48(11): 1946 - 1954. [Abstract] [Full Text] [PDF]

				G. R. Warnick, W. G. Miller, P. P. Waymack, and F. P. Anderson Lack of Agreement of Homogeneous Assays with the Reference Method for LDL-Cholesterol May Not Indicate Unreliable Prediction of Risk for Cardiovascular Disease * Authors of the article cited above respond: Clin. Chem., October 1, 2002; 48(10): 1812 - 1815. [Full Text] [PDF]