Department of Internal Medicine II - Cardiology, University of Ulm Medical Center, Ulm, Germany.
Clin Chem. 2010 May;56(5):861-4. doi: 10.1373/clinchem.2010.143719. Epub 2010 Mar 18.
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.
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.
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.
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.
在众多新兴的生物标志物中，高敏 C 反应蛋白（hsCRP）和白细胞介素 6（IL-6）受到了广泛关注，并且已经积累了大量关于它们作为心血管风险预测因子的潜在作用的数据。然而，炎症生物标志物的浓度受到多种因素的影响，其中包括生理变化，即随时间发生的个体内自然变化。将 hsCRP 和 IL-6 测量值应用于临床实践需要有关此类测量值可靠性的数据。
我们对参加 AIRGENE 研究的 200 名心肌梗死后患者的多达 6 个每月间隔采集的血液样本进行了 hsCRP 和 IL-6 浓度的连续测量。
所有参与者所有样本的血浆浓度（以 hsCRP 的毫克/升和 IL-6 的纳克/升为单位进行对数转换）的平均值（标准差）分别为 hsCRP 的 0.16（1.04）和 IL-6 的 0.76（0.57），男性和女性之间没有显著差异。ln 转换的 hsCRP 数据的个体内和分析方差分量为 0.37，个体间方差分量为 0.73。对于 ln 转换的 IL-6 数据，这些值分别为 0.11 和 0.22。血浆 hsCRP 和 IL-6 浓度的总变异量有很大一部分由个体间变异解释（占总方差的百分比，ln 转换的 hsCRP 数据为 66.1%，ln 转换的 IL-6 数据为 66.2%）。对于这两种标志物，需要进行 2 次测量才能达到足够的可靠性。
我们的结果表明，hsCRP 和 IL-6 的连续测量具有相当大的稳定性和良好的可重复性。因此，如果至少进行 2 次后续测量，在临床实践中不应担心出现错误分类的问题。
