Ross J W, Miller W G, Myers G L, Praestgaard J
Department of Pathology and Clinical Laboratories, Promina Kennestone Hospital, Marietta, GA 30060, USA.
Arch Pathol Lab Med. 1998 Jul;122(7):587-608.
Better procedures are needed whereby national proficiency testing survey providers can assess and improve the accuracy of laboratory measurements in clinical chemistry.
The 1994 College of American Pathologists Comprehensive Chemistry Survey.
This study of matrix effects and the accuracy of laboratory measurements for 11 analytes linked the logistics of the Survey to definitive methods at the National Institutes of Standards and Technology, reference methods at the Centers for Disease Control and Prevention, proficiency testing materials, and a fresh frozen serum sample. The data were analyzed with a statistical model of laboratory measurements.
(1) Matrix biases affected the results reported from 69% of the 644 peer group/survey specimen pairs evaluated. (2) Because of matrix biases, the reference value was the correct target value only 32% of the time; thus, the traceability established by definitive method and reference method value assignments on Chemistry Survey specimens did not assure accuracy on patient samples. (3) In contrast to matrix biases, the error caused by random matrix effects with proficiency testing samples was about the same as that caused by random specimen effects with fresh frozen serum, and both were less than within-run random analytic error. (4) Calibration biases occurred in 73% of the 180 peer groups evaluated, and, after matrix biases were removed, the total variance of interlaboratory measurements was due to peer group calibration bias (48%), within-peer-group random calibration error (31 %), within-run random error (14%), and random specimen effects (7%).
An opportunity exists to improve method calibration accuracy in clinical chemistry. With improved design, national proficiency testing surveys can monitor and help reduce method calibration error by converting reported survey results to a true accuracy base that predicts accuracy on patient samples. For medical purposes, the correct target values on artificial (matrix-modified) chemistry materials are reference values adjusted for the matrix bias of each peer group. Matrix biases estimated by the use of fresh frozen serum can be used as factors to transfer the accuracy of definitive methods from artificial reference materials to patient samples.
需要更好的程序，以便国家能力验证调查机构能够评估并提高临床化学实验室测量的准确性。
1994年美国病理学家学会综合化学调查。
本研究针对11种分析物的基质效应和实验室测量准确性，将调查的后勤工作与美国国家标准与技术研究院的决定性方法、疾病控制与预防中心的参考方法、能力验证材料以及一份新鲜冷冻血清样本联系起来。使用实验室测量的统计模型对数据进行分析。
（1）在所评估的644个同组/调查样本对中，69% 的样本对报告结果受到基质偏差的影响。（2）由于基质偏差，参考值仅在32% 的时间内是正确的目标值；因此，通过决定性方法和化学调查样本的参考方法值赋值建立的可追溯性并不能确保患者样本的准确性。（3）与基质偏差相反，能力验证样本的随机基质效应所导致的误差与新鲜冷冻血清的随机样本效应所导致的误差大致相同，且两者均小于批内随机分析误差。（4）在所评估的180个同组中，73% 出现了校准偏差，并且在消除基质偏差后，实验室间测量的总方差归因于同组校准偏差（48%）、同组内随机校准误差（31%）、批内随机误差（14%）和随机样本效应（7%）。
临床化学领域存在提高方法校准准确性的机会。通过改进设计，国家能力验证调查可以通过将报告的调查结果转换为预测患者样本准确性的真实准确性基础，来监测并帮助减少方法校准误差。出于医学目的，人工（基质改良）化学材料上的正确目标值是针对每个同组的基质偏差进行调整后的参考值。使用新鲜冷冻血清估计的基质偏差可用作将决定性方法的准确性从人工参考材料转移到患者样本的因子。
