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Letters |
1 Sullivan Nicolaides Pathology 134 Whitmore St. Taringa Qld 4068, Australia
aAuthor for correspondence.
| The first 20% of the full text of this article appears below. |
To the Editor:
Last year, Ockene et al. (1) published a report in this journal that made the claim that high-sensitivity C-reactive protein (hs-CRP) has a degree of measurement stability that is similar to that of total cholesterol and that this provides further evidence of the potential clinical utility of hs-CRP screening as a novel tool for vascular risk prediction.
The key evidence that Ockene et al. (1) present to justify their claim is a histogram showing an almost identical agreement in terms of group classification between first and second measurements for hs-CRP and total cholesterol. This apparent agreement is spurious and is attributable to the way in which Ockene et al. partitioned the hs-CRP data. Although the total cholesterol data in the histogram are divided into quartiles, the hs-CRP data are partitioned into arbitrary intervals that contain
15%, 20%, 30%, and 35%, respectively, of the sample.
Ockene et al. (1) provide two graphs showing the data for all 113 patients for serial cholesterol and CRP values ranked by mean concentration. These values are different for the two analytes. For cholesterol, the average intraindividual variation is 18.2%, and the intraindividual variation is roughly constant across all the range of data. For CRP, the average intraindividual variation is higher, at 44.2%. It is lowest at
R1 Department of Medicine Divisions of Cardiovascular Medicine and
R2
Preventive and Behavioral Medicine University of Massachusetts Medical School 55 Lake Ave. North Worcester, MA 01655
R3
Department of Epidemiology and Biostatistics University of South Carolina School of Public Health Columbia, SC 29208
R4
Department of Laboratory Medicine Childrens Hospital Harvard Medical School 300 Longwood Ave. Boston, MA 02115
R5
Division of Preventive Medicine Harvard Medical School Brigham and Womens Hospital 900 Commonwealth Ave. East Boston, MA 02215
R6
Department of Biostatistics and Epidemiology School of Public Health and Health Sciences University of Massachusetts Arnold House Box 30430 Amherst, MA 01003
aAuthor for correspondence.
The following articles in journals at HighWire Press have cited this article:
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L. W. Cho, V. Jayagopal, E. S. Kilpatrick, and S. L. Atkin The Biological Variation of C-Reactive Protein in Polycystic Ovarian Syndrome Clin. Chem., October 1, 2005; 51(10): 1905 - 1907. [Full Text] [PDF] |
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T. B. Ledue and N. Rifai Preanalytic and Analytic Sources of Variations in C-reactive Protein Measurement: Implications for Cardiovascular Disease Risk Assessment Clin. Chem., August 1, 2003; 49(8): 1258 - 1271. [Abstract] [Full Text] [PDF] |
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