Variability in the measurement of C-reactive protein in healthy subjects: implications for reference intervals and epidemiological applications

Variability in the measurement of C-reactive protein in healthy subjects: implications for... Abstract We developed a reproducible ELISA for C-reactive protein (CRP), calibrated with WHO Reference Material, for which intra- and interassay CVs were 3.0% and 6.0%, respectively. Analytical recovery was 97.9%. The distribution of CRP in a healthy blood donor population (n = 143) was nongaussian, with 2.5th, 50th, and 97.5th percentile values of 0.08, 0.64, and 3.11 mg/L, respectively. There was no sex-related difference, and the association with age was weak. In a study of variability (by the method of Fraser and Harris (Crit Rev Clin Lab Sci 1989;27:409–37)), the analytical variability was 5.2%; the within-subject variability, CV I , was 42.2%; and the between-subject variability, CV G , was 92.5%. The critical difference for sequential values significant at P ≤0.05 (i.e., the smallest percentage change unlikely to be due to analytical variability or CV I ) was calculated as 118%, and the index of individuality, CV I /CV G , was 0.46. This suggests that CRP, like many clinical chemistry analytes, has limited usefulness in detecting early disease-associated changes when used in conjunction with a healthy reference interval. From a molecular epidemiological standpoint, the usefulness of CRP in longitudinal studies is suggested by the small index of individuality and by observations that ( a ) short-term fluctuations were infrequent, ( b ) all data stayed within the reference interval, and ( c ) relative rankings of the subjects over 6 months only moderately deteriorated. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Clinical Chemistry American Association for Clinical Chemistry

Variability in the measurement of C-reactive protein in healthy subjects: implications for reference intervals and epidemiological applications

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Publisher
American Association for Clinical Chemistry
Copyright
Copyright © 1997 by the American Association for Clinical Chemistry.
ISSN
0009-9147
eISSN
1530-8561
Publisher site
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Abstract

Abstract We developed a reproducible ELISA for C-reactive protein (CRP), calibrated with WHO Reference Material, for which intra- and interassay CVs were 3.0% and 6.0%, respectively. Analytical recovery was 97.9%. The distribution of CRP in a healthy blood donor population (n = 143) was nongaussian, with 2.5th, 50th, and 97.5th percentile values of 0.08, 0.64, and 3.11 mg/L, respectively. There was no sex-related difference, and the association with age was weak. In a study of variability (by the method of Fraser and Harris (Crit Rev Clin Lab Sci 1989;27:409–37)), the analytical variability was 5.2%; the within-subject variability, CV I , was 42.2%; and the between-subject variability, CV G , was 92.5%. The critical difference for sequential values significant at P ≤0.05 (i.e., the smallest percentage change unlikely to be due to analytical variability or CV I ) was calculated as 118%, and the index of individuality, CV I /CV G , was 0.46. This suggests that CRP, like many clinical chemistry analytes, has limited usefulness in detecting early disease-associated changes when used in conjunction with a healthy reference interval. From a molecular epidemiological standpoint, the usefulness of CRP in longitudinal studies is suggested by the small index of individuality and by observations that ( a ) short-term fluctuations were infrequent, ( b ) all data stayed within the reference interval, and ( c ) relative rankings of the subjects over 6 months only moderately deteriorated.

Journal

Clinical ChemistryAmerican Association for Clinical Chemistry

Published: Jan 1, 1997

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