Baadenhuijsen Henk, Kuypers Aldy, Weykamp Cas, Cobbaert Christa, Jansen Rob
Dutch Foundation for Quality Assessment in Clinical Laboratories, University Hospital Nijmegen, Nijmegen, The Netherlands.
Clin Chem Lab Med. 2005;43(3):304-7. doi: 10.1515/CCLM.2005.052.
The performance of suitable secondary reference material for the use of trueness control of six routinely measured clinical enzymes in the Dutch External Quality Assessment (EQA) scheme is described. The reference material of choice was selected using the split-patient-sample between-field method (twin study) design as described in an earlier study of the Calibration 2000 project in The Netherlands. This material, which was proven to be commutable for all wet chemistry systems, was implemented as the national enzyme calibrator. It consisted of a cryo-protected lyophilised serum with additions of recombinant human enzymes. Various batches of the frozen version of this material without cryo-protection additive, called native EQA samples, were used in the general EQA scheme for performance evaluation. The results of Calibration 2000 calibrated and non-Calibration 2000 calibrated laboratories were compared for both the regular (spiked with non-human enzymes) and native EQA samples in terms of precision and bias with established reference method values for the native samples. The regular samples showed mean between-laboratory CV ranges for all six enzymes involved (low-high) of 5.5-10.3% for the non-calibrated users vs. 4.6-10.8% for the calibrated users. For the native samples these respective ranges were 5.2-9.9% vs. 2.2-4.9%. Without exception, the group of Calibration 2000 calibrated users showed the lowest bias against the reference method values. Regular EQA samples (spiked with non-human enzymes) showed poorer performance than native samples and are not suitable for accuracy assessment purposes, the main aim of EQA schemes. Native samples that are commutable should be used for trueness control in current EQA schemes.
本文描述了适用于荷兰外部质量评估（EQA）计划中六种常规检测临床酶准确性控制的二级参考物质的性能。参考物质的选择采用了荷兰校准2000项目早期研究中所述的分患者样本现场间方法（双样本研究）设计。这种经证明可在所有湿化学系统中通用的物质被用作国家酶校准物。它由添加了重组人酶的冷冻保护冻干血清组成。这种无冷冻保护添加剂的冷冻版本物质的不同批次，即所谓的天然EQA样本，被用于一般EQA计划中进行性能评估。就精度和偏差而言，将校准2000校准实验室和未校准2000校准实验室对常规（添加非人源酶）和天然EQA样本的结果与天然样本既定的参考方法值进行了比较。对于所有六种相关酶，未校准用户的常规样本实验室间CV均值范围（低 - 高）为5.5 - 10.3%，而校准用户为4.6 - 10.8%。对于天然样本，这些范围分别为5.2 - 9.9%和2.2 - 4.9%。无一例外，校准2000校准用户组相对于参考方法值的偏差最低。常规EQA样本（添加非人源酶）的性能比天然样本差，不适用于EQA计划的主要目的——准确性评估。在当前的EQA计划中，应使用可通用的天然样本进行准确性控制。
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