Reproducibility in serial C-reactive protein and interleukin-6 measurements in post-myocardial infarction patients: results from the AIRGENE study.

Abstract

BACKGROUND:

Among the numerous emerging biomarkers, high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) have received widespread interest, and a large database has been accumulated on their potential role as predictors of cardiovascular risk. The concentrations of inflammatory biomarkers, however, are influenced, among other things, by physiological variation, which is the natural within-individual variation occurring over time. Implementation of hsCRP and IL-6 measurement into clinical practice requires data on the reliability of such measurements.

METHODS:

We serially measured hsCRP and IL-6 concentrations in up to 6 blood samples taken at monthly intervals from 200 post-myocardial infarction patients who participated in the AIRGENE study.

RESULTS:

The mean (SD) of the ln-transformed plasma concentrations (in milligrams per liter for hsCRP and nanograms per liter for IL-6) for all participants over all samples was 0.16 (1.04) for hsCRP and 0.76 (0.57) for IL-6, with no significant differences between men and women. The within-individual and analytical variance component for the ln-transformed hsCRP data was 0.37, and the between-individual variance component was 0.73. For the ln-transformed IL-6 data, these values were 0.11 and 0.22, respectively. A substantial part of the total variation in plasma hsCRP and IL-6 concentrations was explained by the between-individual variation (as a percentage of the total variance, 66.1% for the ln-transformed hsCRP data and 66.2% for the ln-transformed IL-6 data). For both markers, 2 measurements were needed to reach a sufficient reliability.

CONCLUSIONS:

Our results demonstrate considerable stability and good reproducibility for serial hsCRP and IL-6 measurements. Thus, there should be no major concern about misclassification in clinical practice if at least 2 subsequent measurements are taken.

• Authors: Mahir Karakas, Jens Baumert, Sonja Greven, Regina Rückerl, Annette Peters, Wolfgang Koenig
• Journal: Clinical chemistry (Clin Chem) Vol. 56 Issue 5 Pg. 861-4 (May 2010) ISSN: 1530-8561 [Electronic] England
• PMID: 20299677 (Publication Type: Journal Article)

Chemical References

• Biomarkers
• Interleukin-6
• C-Reactive Protein

Topics

• Adult
• Aged
• Biomarkers (blood)
• C-Reactive Protein (analysis)
• Cohort Studies
• Female
• Humans
• Interleukin-6 (blood)
• Male
• Middle Aged
• Myocardial Infarction (blood, diagnosis)
• Reproducibility of Results